Scuba scheme. The choice of scuba. Backup source of breath

When operating any scuba, before each descent, it is necessary to do a working check.
Carrying out a working check does not take much time and does not require much effort. A properly performed working check of equipment will allow you to avoid many troubles.

1. Check the pressure in the cylinders.
To do this, instead of the reducer, it is necessary to attach a high pressure control pressure gauge. Close the tap on the manometer. Open the main and reserve air supply valves. Read the readings on the manometer. Then close the valve, open the valve on the high pressure gauge (bleed air from the gauge), remove the pressure gauge.
2. External examination.
A) Check the completeness and correct assembly of the scuba gear (fastening of the gearbox, lung machine, clamps, belts, etc.), you can take the scuba by the straps and shake it easily.
B) Adjust the belts
3. Leak test
A) dry.
With the valves closed, try to inhale from the lung machine. At the same time, the tightness of the membrane, exhalation valves, and connections is checked. Everything is fine if you can not take a breath.
B) Wet.
Open all valves. Place the lung machine under the cylinder, and lower the cylinder into the water. If there are air bubbles from under the connections, the scuba gear is defective.
4. Checking the operation of the bypass valve (reserve).
Open the valve of the main air supply, using the forced air supply button of the lung governed demand valve, bleed some air (approximately 20-30 seconds). Next, open the reserve air supply valve. At the same time, you should hear the characteristic noise of air flowing from the cylinder into the cylinder.
This test does not determine the amount of bypass valve actuation. After completing all the steps, you make sure that you have a working bypass valve in your scuba gear and, as a result, there is a reserve.

Scuba gear AVM-5

1. Regulator set pressure adjustment
2. Adjusting the actuation of the pressure relief valve
3. Adjustment of the lung machine
4. Adjusting the operation of the bypass valve (reserve)

Adjustment of the setting pressure of the reducer (8-10 ati)

1. Measurement of the value of the set pressure.
Disconnect the lung machine.
Attach a control pressure gauge (0-16 ati) to the hose.
Close the valve on the control pressure gauge.
Open the main air supply valve.
Measure the pressure (8-10 ati).
Close the main air supply valve.
Open the valve on the control pressure gauge (bleed air)
2. Adjustment.
Unscrew the gearbox cover (1) fig.4
Pull out the piston (2) fig.4. To do this, screw a puller (or pick up a screw) into the threaded hole in the upper part of the piston and pull the puller. Then the piston can be easily pulled out. It is not recommended to use a screwdriver and try to pick up the piston by the edge.
To increase the set pressure, it is necessary to compress the reducer spring (3) fig.4
To reduce - the spring must be weakened.

Two types of gearboxes were produced.
In the first case, to adjust the setting pressure, it is necessary to place or remove special adjusting washers under the spring (3).
In the second case, it is necessary to move the adjusting nut (7) along the thread of the bushing (8) Fig.4.
In both cases, the meaning of all actions is to compress or decompress the spring (3)
Next, the reducer is assembled and the set pressure is again measured.

Manipulations for adjustment and measurement are carried out until the value of the set pressure is equal to 8-10 atm.

Safety valve actuation adjustment (10-12 ati)

All operating instructions for AVM scuba gear recommend adjusting the operation of the safety valve at the repair and control unit (RCU).
The safety valve is screwed onto a special fitting on the RCU. Pressure is applied to the valve, and by means of the compression force of the spring (11) Fig. 5, the valve is adjusted to the required pressure.

In practice, the adjustment is performed in a slightly different way.
1. Adjust reducer to set pressure
2. Loosen the locknut on the safety valve
3. Slowly rotate the valve body (12) fig. 5 counterclockwise to reach the position at which the valve starts to operate.
4. Screw in the valve body (12) half a turn clockwise until the valve stops drawing air.
5. Tighten the locknut.

Thus, we will adjust the valve to an opening pressure that will be slightly higher than the set pressure (by 0.5-2 ati)

Lung valve adjustment

The instruction manual for the scuba gear says that the lung machine cannot be adjusted.
In practice, the ease of breathing (inspiratory resistance) can be adjusted by bending the lever (5) Fig.6. When the lever is bent, the distance between the membrane (4) and the lever (5) fig. 6 changes, the greater the distance, the greater the resistance when inhaling. It should be noted that if the lung machine is adjusted correctly, then when it is placed in water, air will randomly escape with the mouthpiece up. If the lung machine is turned down with the mouthpiece (as shown in Fig. 6), the air stops escaping.

Bypass valve adjustment (reserve)

1. Measurement of the pressure adjustment of the bypass valve.
When measuring this value, it is necessary to charge the device to a pressure of at least 80 atm.
Unscrew the gearbox and lung machine.
With the reserve air supply valve closed, open the main air supply valve.
Bleed the air.
When the air stops coming out, screw a high pressure control pressure gauge (0-250 ati) to the fitting (instead of the reducer).
Close the tap on the manometer.
The pressure gauge should show 0 ati.
Next, open the reserve air supply valve, and wait until the pressure in the cylinders equalizes (the characteristic noise of flowing air will be heard).
The pressure that the pressure gauge will show will correspond to the pressure of the reserve air supply.
Multiplying the obtained value by 2, we get the response pressure of the bypass valve.
The pressure of the reserve air supply should be within 20-30 atm, respectively, the pressure of the bypass valve operation should be within 40-60 atm.
2. Adjustment
If the results of the measurement show the need for adjustment.
Bleed the remaining air from the cylinders.
Loosen clamps
Loosen the union nuts of the adapter (you can use a gas wrench).
Extend the cylinders and remove the adapter (3)
At the point of attachment of the adapter (3) to the cylinder with valves, access to the adjusting nut of the bypass valve will open.
By compressing or unclenching the bypass valve spring, use the adjusting nut to change the setting. If it is necessary to increase the adjustment pressure, then compress the spring (turn the nut clockwise), if it is necessary to reduce it, decompress the spring.
3. Collect the balloon.
4. Charge up to 80 ati.
5. Take a measurement.
6. Repeat adjustment if necessary.

O-rings and machine lubrication

To ensure the tightness of the connections, the device uses rubber sealing rings of various diameters.
To prevent "drying", the rings must be lubricated. For lubrication, technical vaseline (CIATIM 221), or its substitutes, is used.
The lubricated ring must be placed in the lubricant, held for some time (5-10 minutes), then cleaned of excess lubricant and installed in place.
In addition, the rubbing parts of the gearbox (piston) are lubricated in the apparatus. Lubricant is applied and then its excess is removed.

The frequency of device checks.

Operation check - before each descent
Small check (check of all adjustments, lubrication of O-rings) - before the start of the season
Full check (small check + complete disassembly and assembly) - upon receipt from the warehouse, in case of doubt about serviceability, after long-term storage

Homemade scuba gear is an inexpensive underwater breathing device. The authors of numerous reviews claim that this device can replace expensive diving equipment in case of diving to a depth of up to four meters. So, homemade scuba gear - what is it and how to make it?

Human dependence on technology

Those who wondered how to make a homemade scuba gear should remember that any human activity that is not related to the use of any instruments, equipment or other equipment makes one rely only on one's own luck or the help of a friend. These include, for example, swimming. The use of technology by a person - a car or scuba gear - multiplies his capabilities many times over. But in proportion to the complexity of technology, the dependence of a person on it also increases.

A diver equipped with a “mask, fins, snorkel” set finds himself in an unpleasant situation when he loses any of his equipment underwater. But a scuba diver finds himself in a much more difficult situation if the air supply suddenly stops underwater. This can happen at a depth from which it is impossible to ascend in one breath. Bulky scuba gear reduces mobility and increases water resistance. A similar emergency can occur under ice or in a cave. Submariners must pay great attention to the equipment used. This is especially true for those who decide to make a homemade scuba gear.

About the complexity of the issue

Modern scuba diving equipment is focused on his comfort and safety. All nodes and elements of equipment must be thought out to the smallest detail. Specialists have developed rules for the use of equipment, which are strongly not recommended to be violated. A novice amateur who encounters the slightest difficulty in operating the equipment should seek advice from his trainer, since trouble-free use of the equipment is the key to safe

Scuba is a rather complex device. Experts assure that it is quite difficult to create a homemade scuba gear at home. To do this, you must have the appropriate knowledge and be able to work on good turning equipment. Those who are interested in the question of how to make a homemade one should learn as much as possible about this device.

Story

The word "aqualung" in translation means "water lungs". History shows that the apparatus was created gradually. The first to patent the surface air regulator and adapted it for scuba use. In 1878, it was invented. It used pure oxygen. In 1943, the first scuba gear was created. Its authors were the French Emile Gagnan and Jacques-Yves Cousteau.

Device

Those who decide to create a homemade scuba gear should know that this device consists of 3 main parts and several additional devices:

Balloon. Usually one or two containers with a compressed respiratory mixture are used. Each container holds 7 - 18 liters.
Regulator. Consists of a reducer and lung machine. The scuba gear may contain one or more gears.
Buoyancy compressor. An inflatable vest, the special purpose of which is the regulation of the diving depth.
pressure gauge, equipped with a signal that is triggered when the air pressure reaches 30 atmospheres.

Peculiarities

Those wishing to create a homemade scuba gear need to know about the features of its components.

The high-pressure cylinder, which is part of the scuba gear, is a reservoir for storing air. The working pressure in it is 150 atmospheres. A standard cylinder with a capacity of 7 liters at this pressure holds 1050 liters of air.
One-, two- or three-balloon scuba gears are used. Usually the capacity of the cylinders is 5 and 7 liters, but if necessary, 10-, 14-liter cylinders are used.
The shape of the cylinders is cylindrical, with an elongated neck, equipped with an internal thread for attaching a high-pressure tube or branch pipe.
Cylinders are made of steel or aluminium. Steel cylinders are covered with a protective anti-corrosion layer, which is used as zinc. Steel cylinders are stronger than aluminum, but they are less buoyant.
Cylinders are filled with a gas mixture or compressed filtered air. Modern tanks are equipped with overflow protection.
They are connected to an air reducer, which reduces pressure from 150 to 6 atmospheres throughout the operation of the scuba gear. With such pressure indicators, the respiratory mixture enters the lung machine.
The lung machine is the main device in the scuba device, since it is used to supply breathing air, the pressure of which is equal to the water pressure on the diver's chest area.

Types of scuba gear

Those who decide to design a homemade scuba gear should be aware that three types of equipment are used in diving: with open, closed, semi-closed circuits. They are distinguished from each other by the method of breathing used.

open circuit

It is used in inexpensive, light and not having large dimensions equipment. Works exclusively on air supply. When exhaled, the processed composition is released into the environment without mixing with the mixture filling the cylinders. This eliminates oxygen starvation or carbon dioxide poisoning. The system is simple in design and safe to use. But it has a significant drawback: it is not suitable for the high consumption of the respiratory mixture at great depths.

closed circuit

Scuba diving works according to the following principle: the diver exhales air, which is processed - cleaned of carbon dioxide, saturated with oxygen, after which it is again suitable for breathing. System advantages:

small mass;
small dimensions of equipment;
diving in deep water is possible;
a long stay of a scuba diver under water is provided;
there is an opportunity for the diver to go unnoticed.

This type of equipment is designed for a high level of training, it is not recommended for beginners to use it. The disadvantages of the system include its significant cost.

Semi-closed scheme

The principle of operation of such a system is a hybrid of open and closed circuits. Part of the processed mixture is enriched with oxygen, after which it is again available for breathing, and its excess is discharged into the environment. At the same time, different immersion depths provide for the use of various gas breathing cocktails for breathing.

Backup source

Many divers use mini scuba as a backup tank. The mini model is a compact system designed for breathing underwater at shallow depths. It includes a reducer with a mouthpiece and a small-capacity air tank. Air volume indicators depend on the individual characteristics of the scuba diver.

The use of scuba gear

Scuba gear helps a person swim freely underwater. It eliminates the need to walk along the bottom all the time or stay in an upright position. This is due to the widest use of equipment not only by divers, but also by cameramen, repairmen, archaeologists, ichthyologists, hydraulic engineers and photographers, etc.

Many are trying to make a homemade scuba gear with their own hands. The motivation for making such a decision can be both a desire to save money and an irresistible love for technical creativity. Netizens willingly share tips and tricks on how to make a device at home.

"Sparka": homemade scuba gear from a gas cylinder

You will need:

metal-composite, steel aviation ones with cut-off valves for the oxygen line (against kickback) and reverse charging valves. Volume of each: 4 l, weight: 4.200, operating pressure: 150 bar.
Aviation oxygen valve
Flywheel homemade.
Reducer from the aircraft ejection seat.
Soviet gas reducer for propane.
Homemade spring made of steel, etc.

How to make?

The cylinders are connected using stainless steel clamps (can be made from washing machine tanks). Inserts made of wood are inserted between the cylinders, covered with epoxy-based fabric, with black PF paint. Holes are drilled in the gearbox cover so that water does not stagnate.
The automatic activation of the oxygen system is removed. A lever with a check is installed.
A self-made regulator for scuba diving can be made from a stainless steel wire spring connected to the safety valve of the gearbox and a duralumin cover with a fitting to the outlet for connecting a lung machine. The reducer is adjusted (pressure setting - 6.5 bar).
A lung machine can be made from a Soviet gas reducer. It is necessary to insert 2 fittings made of a duralumin tube (diameter - 16.5 mm) into its body. Put a mouthpiece with a stainless plate clamp on one of them. In the other, paste a textolite glass with a valve from a gas mask. If one mushroom valve quickly fails, it should be made from a rubber reinforced circle (can be cut from shoe covers of the Soviet chemical kit) and a bolt with a nut that fastens the valve directly to the seat. Instead of the old connecting fitting, a new one is made of duralumin, which is glued on an epoxy basis in place of the old one. Valve seat diameter - 2.5 mm.
To counteract the opening force of compressed air, a self-made pulling spring is installed in the lid, which is hooked to the horizontal pin in the upper part of the lid.
The membrane is made from the same rubber from shoe covers. A washer with a small weight is installed on it to eliminate vibration during inhalation. The inspiratory valve cushion can be machined with a high-speed emery tool by hand from a piece of rubber.
The lung machine is tightened with three bolts. Tightened even by hand, they are able to hold the membrane well. The lower part of the lung machine is equipped with a riveted stainless steel plate, which is installed under the chin, for additional comfort of using the equipment.
Shoulder nylon straps are made from pieces of halyard without adjustment due to the lack of need. The waist belt may not have a quick release buckle.

Description of the result

At a depth of 10 m, scuba gear allows you to perform hard physical work (pulling along the bottom of cobblestones or swimming fast) without the effect of lack of air. It is not equipped with a purge button, but it is quite possible to do without it. The lung governed demand valve only needs to be adjusted at the first application, after which the minimum adjustment is made by moving the inspiratory valves. Works at a pressure of 6-7 bar. Inhalation efforts are characterized as quite acceptable, similar to AVM-5. Weight - 300 g. Connects to the hose without gaskets, using a cone connection. The device is very light (about 11.5 kg), compact and streamlined. It does not have a minimum pressure indicator.

Another option for homemade scuba gear from gas cylinders

Prepare a balloon. A container with a volume of up to 22 liters is used, depending on preferences. You can use 2 cylinders of 4.7-7 liters. For normal diving, a 200 bar cylinder is suitable, for technical diving - 300 bar.
Prepare reducer with pressure similar to cylinder pressure.
Connect the reducer to the cylinder. Make sure that the pressure in it is 6-11 bar higher than the ambient pressure.
Connect a hose to the reducer, attach a lung machine to the hose. If it works properly and the master does not make mistakes, the pressure corresponds to the pressure of the environment.
Attach regulators. Their number depends on the tasks. For the planned recreational diving, 2 regulators are needed: the main and the backup.
Install a buoyancy compensator (not necessary for proper functioning of the scuba unit, but makes diving easier and safer).
Inflate the cylinder with oxygen and check the assembled system. If all its elements are connected without errors and the device works, you should carry out the first trial dive to a shallow depth. If it was successful, the scuba gear can be considered ready for use.

Homemade fire extinguisher scuba gear

A cylinder from a carbon dioxide fire extinguisher is used (pressure - 150 bar, capacity - 5 l, weight - about 7.5 kg)
The valve must be turned to a round shape, screwed into a T-shaped fitting (from a cylinder from an ejection seat), which must be equipped with a charging valve.
Two dural plates are installed on it, pulled together.
They are reinforced with a gearbox, which is a converted second stage of the oxygen reducer from the ejection seat (operates from 8 bar).
A self-made safety valve is made, the diameter of the membrane is reduced using 2 plates.
A reducer valve seat with a diameter of 1.2 mm is being made, a valve cushion (from fluoroplastic), in addition, some other minor alterations must be made.
The lung machine is similar to the model described above (see the Sparka section: homemade scuba from a gas cylinder). A housing from another gearbox is used, as well as homemade exhalation and inhalation valves. The balloon is fixed with duralumin clamps on the fiberglass back.

Result

The device is reliable and trouble-free in operation. The main maintenance problem is the corrosion of the duralumin gearbox housing in salt water. To solve the problem, it is recommended to use silicone grease. The equipment is not equipped with a pressure gauge, there are no filters (you can use a siphon tube in a cylinder with small holes at the end). Weight - 9.5 kg.

On the Internet, there are other options for home-made scuba models from a fire extinguisher.

Option number 1

The device is made from a cylinder - a receiver (2 l) from a fire extinguisher.
Attaches to chest area.
Instead of a regulator, a self-made pneumatic button is used to manually supply air for inspiration.
The device is equipped with a non-return valve, which cuts off the air line in the event of a rupture of the hose supplying air.
There is no gearbox, therefore it is used at a limited immersion depth.
The diaphragm is pressed against the valve seat by a spring. When you press the lever, it rises and the air goes to the breath. Exhalation is made into the water using the exhalation valve.
Air supply from the surface is carried out from a transport welding cylinder with a volume of up to 40 liters. A lung machine is connected to the apparatus.
A pneumatic button attached to the hand is more convenient than a button that you have to hold in your hand. The hand is partially released and used to perform some kind of work.

Option number 2

A fire extinguisher cylinder (1.5 l) is used.
The device uses a manual inhalation system.
The equipment is equipped with a valve - a pneumatic button, a valve and a reducer.
It consists of a tube screwed into the fitting from a fire extinguisher, in which there is a plastic check valve pressed against a conical seat by compressed air and a spring. A body with a membrane and a pin pressing on the plastic valve is screwed onto the tube. On the reverse side is a lever designed to be pressed with a finger.
The air leaving this device passes through a nozzle (diameter - 2 mm), then goes to the mouthpiece for inhalation. Exhalation is carried out using a valve.
The weight belt is quite simple to manufacture. It is made from lead cylinders cast from a duralumin tube with a longitudinal section. Equipped with a self-made quick-release buckle.

There is no doubt about the reliable functioning of the equipment, but the tightness of the plastic valve that closes the cylinder is problematic

How to make scuba gear from a bottle?

The Internet offers instructions on how to make homemade scuba gear from a bottle. According to the author who provided it, a sprayer used in horticulture can be used for this. The easiest way to find it is in a specialized store for gardeners. When choosing a container, you should not give preference to too large bottles: they will strongly “pull” upwards.

You will need:

sprayer (pump);
flexible hose (plastic);
underwater snorkel used for diving;
container (bottle).

Technology:

First, remove the limiter installed in the sprayer. This is necessary so that as much air as possible comes out of the sprayer.
A hose is pulled over the top of the sprayer, carefully sealed with silicone or hot glue.
A cap from a plastic bottle is installed on the bottom of the underwater tube, with a pre-drilled hole according to the diameter of the hose.
A hose is inserted into the hole, carefully sealed, sealed. A simple scuba gear is ready.

Operating principle

The bottle is connected to a pump sprayer and filled with air. The 330 ml container is filled with air with 50 strokes. This amount of air is sufficient for 4 full breaths. A larger container should be equipped with a load, as an air-filled bottle will float up. To extract air from the bottle, just press the appropriate button on the atomizer.

Conclusion

Self-made scuba will save money and provide an opportunity to experience the incomparable pleasure of participating in the creative process. In order to ensure the safety of their own life and health, craftsmen must strictly follow the instructions.

Scuba gear helps people dive underwater to great depths. Having a scuba gear behind them, divers move freely under water, they do not need to take hoses with them, into which air is supplied from the ship.

Air supplies in scuba gear are stored in two or more steel cylinders, and the air in them is in compressed form. With the help of a special valve, the respiratory mixture in small quantities is released from the cylinder into a tube connected to the mouthpiece. A diver holds such a muzzle with his teeth. Since the scuba diver's nose is clamped by special protrusions in an underwater mask, he breathes through his mouth.

Scuba is fastened to a person with special soft straps and a belt, heavy, like an anchor. By the way, such a belt helps the scuba diver stay underwater. Thanks to modern scuba gear, a person moves under water as easily and freely as fish. The diver has large flippers on his feet, with which he rakes in the water, thereby freeing his hands. Therefore, a diver can take an underwater camera or speargun with him. In shallow waters, scuba divers dive for more than half an hour.

But even wearing the most modern diving suit, scuba divers will not be able to dive to a depth of more than 100 meters. At such a depth, water presses on objects with such force that everything seems ten times heavier than on its surface. Therefore, the air in scuba tanks begins to be consumed ten times faster.

Even having equipped the scuba with huge cylinders, the diver cannot stay at such a depth for more than two minutes.

Unfortunately, the scuba diver faces other dangers. Scuba tanks are four-fifths filled with nitrogen and one-fifth with oxygen, that is, oxygen and nitrogen are in the same proportion as in ordinary air. Oxygen is vital for man. As for nitrogen, it is simply excreted from the body. But under high pressure, some of the nitrogen begins to dissolve in the blood and be absorbed by muscle tissue.

When a scuba diver rises to the surface, nitrogen must be removed from his blood and muscle tissue. If it does not quickly exit through the lungs, then nitrogen stagnates, turning into tiny bubbles in the human body. Such bubbles pinch nerve endings and clog blood vessels, causing an air embolism in a person, a disease accompanied by very severe pain. An air embolism can be fatal or leave a person crippled for life.

That is why scuba divers should ascend from a depth of 80-100 meters very slowly, with frequent stops.

The main task of an underwater breathing apparatus (scuba gear) is to provide a balanced supply of air to the diver's lungs at a pressure equal to that of the environment. Scuba gear consists of three main parts:

Cylinders. High-strength steel tanks into which air is pumped under high pressure. Recently, aluminum alloy cylinders have been used. The pressure in the cylinder is 200 - 300 atm.
Pressure regulator. It is a reducer for converting high pressure in a cylinder into low pressure, under which air is supplied to the breathing mask.
Accessories: mask, connecting hoses, attachment straps and weight system.
Buoyancy compensator. It is a rubber container into which air is pumped depending on the depth of immersion.

Most often refuel with clean dehydrated air. Also used are various breathing mixtures made up of oxygen, nitrogen and helium. They are especially necessary at a large depth of immersion. A special compressor is used to fill the cylinders. It compresses the air to the required pressure and also cleans it of water particles and lubricating oil. The purity of the breathing mixture is the most important condition for safe diving. Multi-stage filters with adsorbents and separators are used. Cylinders are recommended to be stored filled, as then the ingress of foreign substances and water is excluded, which greatly increases the corrosion of the inner surface.

The pressure regulator is the most important part of the diving apparatus. Now they use combined models. They simultaneously perform several functions:

Reducing the air pressure to the required value, which depends on the depth of the dive.
Control over the pressure in the cylinder (a pressure gauge is installed on the body).
Attachment of breathing hoses to the mask. Exhaust valve placement.

The single stage is mounted on the valves of the cylinders on the back. When positioned face down (and this is one of the main positions of the diver), it is 20 - 30 centimeters above the lungs, which makes it difficult to breathe. Therefore, now began to use a two-stage system. The node of the second stage is referred to as a lung machine, and the first - a pressure reducer. The two-stage system has good functionality and is especially used in diving clubs, as it provides comfort.

The regulator reducer is placed as close as possible to the cylinder for safety reasons, since the connection is made by a high pressure line. Sometimes two reducers are used, separate for each cylinder. The pressure in the line from the reducer to the lung machine is 10 - 15 atm. The lung machine is hung on the mask. In particularly critical cases, a backup respiratory system is used. Then the circuits from both cylinders are made completely separate and independent of each other.

Of great importance for safe diving is the subjective control of air consumption. The main device that is used for this is a manometer. Now they do it analog. It is characterized by simplicity and reliability. Digital instruments are not yet widely used, but they make it easier to count the remaining time of the dive. The manometer directly controls the pressure in the cylinder and is connected to it by a flexible high pressure line.

All main parts of the diving apparatus are connected into a single system using various rubber hoses. Straps secure the device on the back. The buoyancy compensator has the form of a vest with a container filled with air. Thanks to the compensator, as you dive into an increasingly dense environment of water, the diver's buoyancy remains unchanged.

The main problem under water is that a person has nothing to breathe there! That is why all inventions related to underwater equipment were primarily devoted to ensuring free breathing.

The evolution of thought

The evolution of underwater breathing equipment is quite interesting and fully reflects the general course of human thought. The first thing that comes to mind is that if there is no air under water, it must be supplied there. The easiest way to do this is with a breathing tube, one end of which is above the water. However, not all so simple! If you have ever tried to dive, trying to breathe through a long tube or hose, then you know that the human lungs are unable to overcome the water pressure and take a breath already at a depth of 1-1.5 m.
Therefore, this method is suitable only for swimming on the surface, and many of our readers have probably used it more than once, snorkeling. The next idea - to breathe air at a pressure equal to the pressure of water, led to the invention of a diving bell. It was proposed by Guglielmo de Loreno in 1530. The design of the bell was very simple - a hollow barrel without a bottom, immersed with an open end in water. The pressure in such a bell, due to the open end of the barrel and, consequently, the movable air-water boundary, is equal to the external water pressure at a given depth. Working underwater, you can inhale from the barrel from time to time without floating to the surface. One bad thing - the air in the barrel quickly ends.

Of course, the air supply can be replenished. By supplying air to the bell from the surface using a pump, you can significantly extend the stay of a person under water. Of course, this will require the use of an air pump (and the deeper we go, the more powerful the pump must be). However, working (or simply observing the underwater world) is still not very convenient: the diver remains rather rigidly tied to the surface with a hose and a bell and is able to “break away” from them only for the duration of holding his breath.

I carry everything with me

Alas, this problem can only be overcome with the help of self-contained breathing apparatus. In English, there is a special abbreviation for such devices - SCUBA (Self-contained Breathing Underwater Apparatus). The first such apparatus was proposed in 1825 by the Englishman William James. The device consisted of a rigid cylinder in the form of a belt around the diver's waist, filled with air at a pressure of about 30 atmospheres, and a breathing hose connecting the cylinder to a diving helmet. It was inconvenient: the air was constantly supplied to the helmet and due to this (and the low pressure in the tank) it quickly ended.

To overcome this shortcoming, it is necessary to supply breathing air only at the moment of inhalation. This is done using diaphragm-operated valves that respond to the vacuum created by the lungs. This is exactly how the Aerofor device was designed, invented in 1865 by the Frenchmen Benoit Ruqueirol and Auguste Deneyrouz. Their design was a steel cylinder with air under a pressure of 20–25 atmospheres horizontally located on the back of a diver, connected through a pressure reducing valve to a mouthpiece. The membrane pressure reducing valve supplied air only at the moment of inhalation at a pressure equal to the water pressure.

Aerofor was not completely autonomous: the cylinder was connected by a hose through which air was supplied to the surface, but if necessary, the diver could be disconnected for a short time. Aerofor is the forerunner of modern open-cycle breathing equipment (a diver inhales air from a cylinder, exhales into water) for diving. It was used for several years by the French (and not only) navy, and even in 1870 it was mentioned in Jules Verne's book Twenty Thousand Leagues Under the Sea.

There was only one step left for the Aerofor apparatus to its modern form - this is a step towards a supply of high-pressure air. And this step has been taken. But “one step forward, two steps back” - in 1933, the captain of the French navy, Yves Le Prior, modified the Rouquerol-Deneurose apparatus, combining a manual valve with a high-pressure cylinder (100 atmospheres). This made it possible to obtain a longer autonomy time, but the control was extremely inconvenient - when inhaling, the valve was opened manually, while exhalation was made into the mask (through the nose).

And finally, in 1943, Jacques-Yves Cousteau and Emile Gagnan put all the ideas together and give the breathing apparatus the form in which it has come down to us. They connect two cylinders with air (100-150 atmospheres), a special step-down gas reducer and a valve that supplies air under pressure exactly equal to the pressure of the external environment, and only at the moment of inspiration. The Ruqueirol-Deneirouz regulator, which was 78 years ahead of the design of Cousteau and Gagnan, was forgotten for unknown reasons.

Cousteau and Ganyan decided to name their apparatus "Aqua Lung", that is, "Underwater lungs". It was under this name that he became known to the whole world. The word "scuba" has become a household word and entered many languages of the world as a synonym for underwater breathing apparatus.

Modern scuba

Let's take a closer look at how modern scuba gear works. Despite the fact that quite a few years have passed since 1943, modern breathing apparatus are not far from their ancestor - the Cousteau-Ganyan scuba gear. Yes, of course, technologies have changed, new materials have appeared, but the principles of work have remained absolutely the same.

The main components of the breathing apparatus are a cylinder with air under high (200–300 atmospheres) pressure and a two-stage gearbox.

What is a reducer for?

The fact is that it is simply dangerous to supply air for breathing directly from a cylinder under a pressure of 200 atmospheres: the lungs will not withstand such pressure. Therefore, a special reducing (pressure-reducing) valve is attached to the cylinder. Its first stage reduces the pressure to 6-15 atmospheres (depending on the design and model).

The second stage, usually called the regulator (or lung machine), performs two important tasks. The first is to supply air at a pressure that exactly matches the pressure of the water at any depth. This allows the diver to breathe at any depth without any effort or discomfort.

The second task of the regulator is to supply breathing air only at the moment of inhalation (this allows you to spend air much more economically). At the moment of inhalation, the human lungs create a vacuum, a special membrane-controlled valve reacts to this and opens the air supply.

Exhalation occurs through poppet membrane valves directly into the water. Thus, the air is used only once. Therefore, sometimes scuba is called an open circuit breathing system.

As you can see, the design of the scuba gear is very simple and therefore reliable. Ease of manufacture and maintenance and reliability have ensured many years of scuba success. It was with scuba gear that the real era of exploration of the deep sea began.

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The business associated with such an exciting activity as scuba diving is quite a profitable business. In this article, we suggest that you familiarize yourself with the variety of diving equipment that you will need when opening your own diving school or diving company.

Variety of wetsuits
Mask and fins
Types of scuba gear

The basic scuba equipment is the No. 1 diving set, consisting of three items: fins, mask and snorkel. You can also add a wetsuit with waist weights for a comfortable swim.

A complete set of underwater diving equipment includes:

wetsuit, fins, mask;
buoyancy compensator;
weight belt;
scuba (rebreather) - a cylinder filled with air or an air mixture, a regulator;
gloves, boots, helmet;
depth gauge, underwater watch or a computer that combines all these functions.

Additionally, a flashlight, coil, tow, compass, snorkel, etc. can be used.

Variety of wetsuits

A wetsuit is an integral part of diving equipment, provides thermal insulation, protects the swimmer from the negative effects of the external environment (animal bites, cuts, abrasions).

Required suit thickness

1. Tight Bodyskin- when immersed in warm waters, does not restrict movement, light. Made from stretchy lycra, nylon in vibrant colors. The disadvantage is that it wears out quickly.

2. Drysuit for diving - in cold water with putting on warm underwear underneath. Made from various materials: nylon trilaminate, butyl rubber, nylon or vulcanized rubber.

3. Wetsuit elastic, as it is made of neoprene, easy to put on and take off. The density of the fabric and the style of the cut are selected depending on the expected conditions of the water area. In it, the process of heat loss slows down due to a thin layer of water that heats up from the body. It is applied in warm reservoirs. The tighter the wetsuit fits, the warmer it is.

Aquasphere Aquaskins Dimension Chart

Dimensions	Height, m (female), cm	Weight m. (w.), kg
XS	152-157 (154-160)	47-53 (49-53)
S	160-170 (160-165)	53-61 (53-58)
M	167-175 (165-170)	61-68 (58-62)
L	175-182 (170-175)	67-72 (63-68)
XL	177-185 (175-182)	71-77 (67-72)
XXL	185-195	76-90

What to consider when choosing equipment

Mask and fins

Mask - equipment for eye protection, ensuring clear visibility under water, breathing through the nose.

Fins provide a smooth movement of the diver under water fins made of rubber or plastic.

Open heel fins and a tightening belt are appropriate for cold water. Special shoes are worn under these fins. The disadvantage is that the straps can rub the heels, the legs are not completely protected.

Closed heel fins do not need to put on additional shoes. With the right size and fit, they are affordable and comfortable.

Watch a video about choosing a mask

Types of scuba gear

Scuba gear is diving equipment that allows you to breathe underwater for a long period of time. Provides supply of compressed air or breathing mixture. The minimum equipment for scuba gear, which allows you to breathe underwater, is a cylinder plus a regulator.

There are two main types of scuba gear:

open circuit scuba– the inhaled air is not reused and is discharged into the water. The equipment is portable and convenient to use in recreational diving, cheap. The disadvantage is the impossibility of diving for a long time and considerable depth.
Scuba with a closed circuit, or a rebreather - the air is used several times as it circulates as it passes through the system. Cons: Expensive, difficult to use. This is the underwater equipment of professional divers.

Regulator- a piece of diving equipment that lowers the pressure in the cylinder to ambient pressure, and regulates air flow when inhaling and exhaling. The regulator supplies gas to the diver for breathing.

diving cylinders

This is a part of a cylindrical scuba gear used for storing, transporting gas or a mixture of gases under high pressure:

Standard - 200 bar;
Low - 150-180 bar;
High - 200-300 bar.

The greater the pressure, the thicker the walls of the cylinder, which are usually made of aluminum or steel.

Aluminum cylinders wear out faster and are subject to mechanical stress. Steel - rust from the inside.

Indicators of empty and filled cylinders in water, on land

Cylinder type, l / bar	Air volume, l	Weight on land, kg / kg	Weight in water, kg / kg
Aluminum 9 / 203	1826	12,2 / 13,5	1,8 / -0,5
Aluminum 11 / 203	2247	14,4 / 17,2	1,8 / -1,1
Aluminum 13 / 203	2584	17,1 / 20,3	1,4 / — 1,7
Steel 8 / 300	2400	13 / 16	— 3,5 / — 6,5
Steel 10 / 300	3000	17 / 20,8	— 4 / — 7,8
Steel 12 / 200	2400	16 / 19	— 1,2 / — 3,4
Steel15 / 200	3000	20 / 23,8	— 1,4 / — 5,4

The composition of the balloon includes:

Shut-off valve - a part that tightly connects the regulator and the cylinder, regulates the flow of gas supply;
Y-shaped shut-off valve is a valve for two pairs of outlets and fans for connecting the main, as well as a spare regulator;
The rubber o-ring is a hermetic connection between the shut-off valve and the regulator.

Types of recreational diving cylinders:

The main one - with a capacity, usually from 10 to 18 liters;
Spare - emergency air reserve, volume from 0.4 to 1 liter;
A balloon pony is a small reserve.

Varieties of buoyancy compensators

Buoyancy compensator (BCD)- equipment used to control buoyancy during a dive or ascent by adding or releasing a certain amount of air from a special chamber.

Winged compensator- completely located on the back. Effective for underwater shooting, technical diving. The advantage of this equipment is that the front of the body is free.

Compensator in the form of a vest allows you to achieve buoyancy with a volume of 25 liters. Doesn't restrict movement.

Lightweight and affordable equipment is adjustable compensator buoyancy volume up to 15 liters. It has one inconvenience - fastening around the neck, between the legs.

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Scuba gear is a modern device for deep diving. It allows the diver to breathe underwater without being dependent on the air supply from the ship. The scuba diver carries his own supply of air with him attached to his back. He is a free diver. The compressed air supply is contained in one (or more) steel scuba cylinders. A tube extends from the valve leading to the mouth. It is made in such a way that the diver can hold it with his teeth. The nose is covered with a mask, and the scuba diver breathes through one mouth. With a scuba gear on his back and a special heavy belt to keep him underwater, a person can swim almost as freely as a fish.

When swimming, large flippers on the legs are used to do without the help of the hands being freed, so as to hold the camera or harpoon. If you do not dive to great depths, the scuba diver can stay under water for half an hour or more. But even the most modern scuba gear does not allow a person to go deeper than a hundred meters. At this depth, the gravity of the water column exerts a pressure ten times greater than at the surface. The air in the cylinders is consumed ten times faster, so that even very large cylinders last only a few minutes.

There is another problem associated with diving to very great depths. Compressed air in cylinders, like atmospheric air, consists of four-fifths of nitrogen and only one-fifth of oxygen. We need oxygen to sustain life. Normally, the nitrogen we breathe in is immediately breathed out. But under conditions of increasing air pressure, part of the nitrogen dissolves in the blood and tissues.

When a scuba diver ascends, nitrogen must be removed from his blood and tissues. If it cannot leave the body quickly enough through the lungs, it begins to turn into small bubbles in the body. The bubbles pinch the nerves and clog the blood vessels, and the scuba diver develops decompression sickness, accompanied by terrible pain. As a result of severe cases of decompression sickness, a person can die or remain disabled for life. That is why the scuba diver must rise to the surface very slowly if he was at a depth of sixty to one hundred meters. During the ascent, he must make frequent stops.

Next chapter >

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Cylinders. High-strength steel tanks into which air is pumped under high pressure. Recently, aluminum alloy cylinders have been used. The pressure in the cylinder is 200 - 300 atm.
Pressure regulator. It is a reducer for converting high pressure in a cylinder into low pressure, under which air is supplied to the breathing mask.
Accessories: mask, connecting hoses, attachment straps and weight system.
Buoyancy compensator. It is a rubber container into which air is pumped depending on the depth of immersion.

Most often diving cylinders filled with clean dehydrated air. Also used are various breathing mixtures made up of oxygen, nitrogen and helium. They are especially necessary at a large depth of immersion. A special compressor is used to fill the cylinders. It compresses the air to the required pressure and also cleans it of water particles and lubricating oil. The purity of the breathing mixture is the most important condition for safe diving. Multi-stage filters with adsorbents and separators are used. Cylinders are recommended to be stored filled, as then the ingress of foreign substances and water is excluded, which greatly increases the corrosion of the inner surface.

The pressure regulator is the most important part of the diving apparatus. Now they use combined models. They simultaneously perform several functions:

Reducing the air pressure to the required value, which depends on the depth of the dive.
Control over the pressure in the cylinder (a pressure gauge is installed on the body).
Attachment of breathing hoses to the mask. Exhaust valve placement.

single stage diving regulator mounted on the valves of the cylinders on the back. When positioned face down (and this is one of the main positions of the diver), it is 20 - 30 centimeters above the lungs, which makes it difficult to breathe. Therefore, now began to use a two-stage system. The node of the second stage is referred to as a lung machine, and the first - a pressure reducer. The two-stage system has good functionality and is especially used in diving clubs, as it provides comfort.

Of great importance for safe diving is the subjective control of air consumption. The main device that is used for this is a manometer. Now diving gauges do it analog. It is characterized by simplicity and reliability. Digital instruments are not yet widely used, but they make it easier to count the remaining time of the dive. The manometer directly controls the pressure in the cylinder and is connected to it by a flexible high pressure line.

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Human dependence on technology

About the complexity of the issue

Modern scuba diving equipment is focused on his comfort and safety. All nodes and elements of equipment must be thought out to the smallest detail. Specialists have developed rules for the use of equipment, which are strongly not recommended to be violated. A novice amateur who encounters the slightest difficulty in operating the equipment should seek the advice of his trainer, as trouble-free use of the equipment is the key to safe diving.

Scuba is a rather complex device. Experts assure that it is quite difficult to create a homemade scuba gear at home. To do this, you must have the appropriate knowledge and be able to work on good turning equipment. Those who are interested in the question of how to make a homemade scuba gear with their own hands should learn as much as possible about this device.

Story

The word "aqualung" in translation means "water lungs". History shows that the apparatus was created gradually. The first to patent the surface air regulator and adapted it for scuba use. In 1878, an underwater breathing apparatus was invented. It used pure oxygen. In 1943, the first scuba gear was created. Its authors were the French Emile Gagnan and Jacques-Yves Cousteau.

Device

Those who decide to create a homemade scuba gear should know that this device consists of 3 main parts and several additional devices:

Balloon. Usually one or two containers with a compressed respiratory mixture are used. Each container holds 7 - 18 liters.
Regulator. Consists of a reducer and lung machine. The scuba gear may contain one or more gears.
Buoyancy compressor. An inflatable vest, the special purpose of which is the regulation of the diving depth.
pressure gauge, equipped with a signal that is triggered when the air pressure reaches 30 atmospheres.

Peculiarities

Those wishing to create a homemade scuba gear need to know about the features of its components.

The high-pressure cylinder, which is part of the scuba gear, is a reservoir for storing air. The working pressure in it is 150 atmospheres. A standard cylinder with a capacity of 7 liters at this pressure holds 1050 liters of air.
One-, two- or three-balloon scuba gears are used. Usually the capacity of the cylinders is 5 and 7 liters, but if necessary, 10-, 14-liter cylinders are used.
The shape of the cylinders is cylindrical, with an elongated neck, equipped with an internal thread for attaching a high-pressure tube or branch pipe.
Cylinders are made of steel or aluminium. Steel cylinders are covered with a protective anti-corrosion layer, which is used as zinc. Steel cylinders are stronger than aluminum, but they are less buoyant.
Cylinders are filled with a gas mixture or compressed filtered air. Modern tanks are equipped with overflow protection.
They are connected to an air reducer, which reduces pressure from 150 to 6 atmospheres throughout the operation of the scuba gear. With such pressure indicators, the respiratory mixture enters the lung machine.
The lung machine is the main device in the scuba device, since it is used to supply breathing air, the pressure of which is equal to the water pressure on the diver's chest area.

Types of scuba gear

open circuit

It is used in inexpensive, light and not having large dimensions equipment. Works exclusively on air supply. When exhaled, the processed composition is released into the environment without mixing with the mixture filling the cylinders. This eliminates oxygen starvation or carbon dioxide poisoning. The system is simple in design and safe to use. But it has a significant drawback: it is not suitable for deep diving due to the high consumption of the respiratory mixture at great depths.

closed circuit

small mass;
small dimensions of equipment;
diving in deep water is possible;
a long stay of a scuba diver under water is provided;
there is an opportunity for the diver to go unnoticed.

This type of equipment is designed for a high level of training, it is not recommended for beginners to use it. The disadvantages of the system include its significant cost.

Semi-closed scheme

Backup source

The use of scuba gear

"Sparka": homemade scuba gear from a gas cylinder

You will need:

Oxygen cylinders, metal-composite, steel aviation cylinders with cut-off valves for the oxygen line (against kickback) and check valves. Volume of each: 4 l, weight: 4.200, operating pressure: 150 bar.
Aviation oxygen valve
Flywheel homemade.
Reducer from the aircraft ejection seat.
Soviet gas reducer for propane.
Homemade spring made of stainless steel wire, etc.

How to make?

The cylinders are connected using stainless steel clamps (can be made from washing machine tanks). Inserts made of wood are inserted between the cylinders, covered with epoxy-based fabric, with black PF paint. Holes are drilled in the gearbox cover so that water does not stagnate.
The automatic activation of the oxygen system is removed. A lever with a check is installed.
A self-made regulator for scuba diving can be made from a stainless steel wire spring connected to the safety valve of the gearbox and a duralumin cover with a fitting to the outlet for connecting a lung machine. The reducer is adjusted (pressure setting - 6.5 bar).
A lung machine can be made from a Soviet gas reducer. It is necessary to insert 2 fittings made of a duralumin tube (diameter - 16.5 mm) into its body. Put a mouthpiece with a stainless plate clamp on one of them. In the other, paste a textolite glass with a valve from a gas mask. If one mushroom valve quickly fails, it should be made from a rubber reinforced circle (can be cut from shoe covers of the Soviet chemical kit) and a bolt with a nut that fastens the valve directly to the seat. Instead of the old connecting fitting, a new one is made of duralumin, which is glued on an epoxy basis in place of the old one. Valve seat diameter - 2.5 mm.
To counteract the opening force of compressed air, a self-made pulling spring is installed in the lid, which is hooked to the horizontal pin in the upper part of the lid.
The membrane is made from the same rubber from shoe covers. A washer with a small weight is installed on it to eliminate vibration during inhalation. The inspiratory valve cushion can be machined with a high-speed emery tool by hand from a piece of rubber.
The lung machine is tightened with three bolts. Tightened even by hand, they are able to hold the membrane well. The lower part of the lung machine is equipped with a riveted stainless steel plate, which is installed under the chin, for additional comfort of using the equipment.
Shoulder nylon straps are made from pieces of halyard without adjustment due to the lack of need. The waist belt may not have a quick release buckle.

Description of the result

Another option for homemade scuba gear from gas cylinders

Prepare a balloon. A container with a volume of up to 22 liters is used, depending on preferences. You can use 2 cylinders of 4.7-7 liters. For normal diving, a 200 bar cylinder is suitable, for technical diving - 300 bar.
Prepare reducer with pressure similar to cylinder pressure.
Connect the reducer to the cylinder. Make sure that the pressure in it is 6-11 bar higher than the ambient pressure.
Connect a hose to the reducer, attach a lung machine to the hose. If it works properly and the master does not make mistakes, the pressure corresponds to the pressure of the environment.
Attach regulators. Their number depends on the tasks. For the planned recreational diving, 2 regulators are needed: the main and the backup.
Install a buoyancy compensator (not necessary for proper functioning of the scuba unit, but makes diving easier and safer).
Inflate the cylinder with oxygen and check the assembled system. If all its elements are connected without errors and the device works, you should carry out the first trial dive to a shallow depth. If it was successful, the scuba gear can be considered ready for use.

Homemade fire extinguisher scuba gear

A cylinder from a carbon dioxide fire extinguisher is used (pressure - 150 bar, capacity - 5 l, weight - about 7.5 kg)
The valve must be turned to a round shape, screwed into a T-shaped fitting (from a cylinder from an ejection seat), which must be equipped with a charging valve.
Two dural plates are installed on it, pulled together.
They are reinforced with a gearbox, which is a converted second stage of the oxygen reducer from the ejection seat (operates from 8 bar).
A self-made safety valve is made, the diameter of the membrane is reduced using 2 plates.
A reducer valve seat with a diameter of 1.2 mm is being made, a valve cushion (from fluoroplastic), in addition, some other minor alterations must be made.
The lung machine is similar to the model described above (see the Sparka section: homemade scuba from a gas cylinder). A housing from another gearbox is used, as well as homemade exhalation and inhalation valves. The balloon is fixed with duralumin clamps on the fiberglass back.

Result

On the Internet, there are other options for home-made scuba models from a fire extinguisher.

Option number 1

The device is made from a cylinder - a receiver (2 l) from a fire extinguisher.
Attaches to chest area.
Instead of a regulator, a self-made pneumatic button is used to manually supply air for inspiration.
The device is equipped with a non-return valve, which cuts off the air line in the event of a rupture of the hose supplying air.
There is no gearbox, therefore it is used at a limited immersion depth.
The diaphragm is pressed against the valve seat by a spring. When you press the lever, it rises and the air goes to the breath. Exhalation is made into the water using the exhalation valve.
Air supply from the surface is carried out from a transport welding cylinder with a volume of up to 40 liters. A lung machine is connected to the apparatus.
A pneumatic button attached to the hand is more convenient than a button that you have to hold in your hand. The hand is partially released and used to perform some kind of work.

Option number 2

A fire extinguisher cylinder (1.5 l) is used.
The device uses a manual inhalation system.
The equipment is equipped with a valve - a pneumatic button, a valve and a reducer.
It consists of a tube screwed into the fitting from a fire extinguisher, in which there is a plastic check valve pressed against a conical seat by compressed air and a spring. A body with a membrane and a pin pressing on the plastic valve is screwed onto the tube. On the reverse side is a lever designed to be pressed with a finger.
The air leaving this device passes through a nozzle (diameter - 2 mm), then goes to the breather into the mouthpiece. Exhalation is carried out using a valve.
The weight belt is quite simple to manufacture. It is made from lead cylinders cast from a duralumin tube with a longitudinal section. Equipped with a self-made quick-release buckle.

There is no doubt about the reliable functioning of the equipment, but the tightness of the plastic valve that closes the cylinder is problematic

How to make scuba gear from a bottle?

You will need:

sprayer (pump);
flexible hose (plastic);
underwater snorkel used for diving;
container (bottle).

Technology:

First, remove the limiter installed in the sprayer. This is necessary so that as much air as possible comes out of the sprayer.
A hose is pulled over the top of the sprayer, carefully sealed with silicone or hot glue.
A cap from a plastic bottle is installed on the bottom of the underwater tube, with a pre-drilled hole according to the diameter of the hose.
A hose is inserted into the hole, carefully sealed, sealed. A simple scuba gear is ready.

Operating principle

Conclusion

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Scuba (lat. Aqua, water + English lung, light = Aqua-lung, “Water lung”), or scuba (English SCUBA, Self-contained underwater breathing apparatus, autonomous breathing apparatus under water) - light diving equipment, allowing you to dive to depths of up to three hundred meters and easily move under water.

Components of a scuba gear
Cylinder - one or two metal cylinders with a volume of 7-18 liters (sometimes there are 20 and 22 liter cylinders).
Regulator - there may be several on one scuba gear (depending on the tasks solved during the dive). It usually consists of two parts: a gearbox and a lung machine.
Buoyancy compensator - not required, but commonly used today.

The work of scuba gear is based on the principle of pulsating air supply for breathing (only for inhalation) in an open pattern, i.e. with exhalation into the water. This eliminates the mixing of exhaled air with inhaled air or its reuse, as happens in devices with a closed cycle.
Breathing in scuba gear is carried out according to the following scheme: air compressed in cylinders enters the lungs through a mouthpiece from a breathing machine, and exhalation is made directly into the water. Air in turn from each cylinder goes through the stopcocks into a metal pipe connected to a pressure reducing valve. A reinforced rubber tube with a manometer located on the swimmer's chest is attached to the nozzle. Reaching back and turning the stopcocks, the swimmer
can determine by the pressure gauge how much air he has left. A pressure gauge is to a swimmer what a gas gauge is to a car driver: it allows the swimmer to judge how long they can stay underwater.
The main part of the scuba design is a respiratory (lung) machine, with the help of which air is supplied to the respiratory organs of a person in the required amount and under pressure corresponding to the pressure of the surrounding water. A special valve closes the exhalation tube during inhalation, and the inhalation tube during exhalation. This prevents the loss of fresh air and the inhalation of used air. The first models of scuba did not have an exhalation tube until Cousteau discovered that the apparatus, which worked perfectly when the swimmer was face down, failed if he rolled onto his back. This is because the air pressure in the breathing valve and in the outlet near the swimmer's mouth were not the same. The way out was found in the fact that by means of an exhalation tube the outlet was moved to the back of the swimmer's head.
According to their design, breathing machines are single-stage and two-stage, without separation of air reduction stages and with separation. At present, two-stage automatic machines with separated reduction stages are mainly used. The scheme of their action is as follows:
Reducer 1 is mounted directly on the cylinder with compressed air. From it, air through a flexible smooth hose 2 enters the breathing machine 6, which is located near the swimmer's mouth. The respiratory automaton is divided by membrane 5 into internal (submembrane) and external (supramembrane) cavities. In the body of the machine there is a swinging inhalation valve 4 with a stem located at an angle to the membrane. When inhaling, a vacuum is created in the internal cavity of the machine. Under the action of external pressure, the membrane, bending into the internal cavity, then presses on the inhalation valve stem and warps this valve 4 relative to the seat. Through the resulting gap, air enters the internal cavity of the machine.
After the end of inspiration, the pressure in the internal cavity equalizes with the external water pressure, the membrane returns to its neutral position and stops pressing on the valve stem. Then, under the influence of the force of spring 3, the valve sits on the seat and stops air from entering the internal cavity of the machine. Exhalation is carried out through the exhalation valves located in the body of the breathing machine.