This translation comes from Chapter III of this 1956 Russian manual.

Diving equipment

Diving equipment is a collection of objects that are put on a diver or attached to a diver in order to make his being under water possible. Some of these objects form a diving suit.  The diving suit provides a watertight and gas-impermeable coating that is put on a diver and isolates him from the environment. 

In this textbook, we consider only the most common types of diving equipment that are used for work at small and medium depths.  These are three-bolt ventilated equipment УBC-50 and the twelve-bolt ventilated equipment. 

18.    Three-bolt ventilated diving equipment

Three-bolt ventilated diving equipment (Figure 6) is used for rescue work, ship salvaging and technical work under water at depths up to 60 m.  It is called ‘three-bolt’ because the helmet is joined to the suit by three bolts with nuts.  It is called ‘ventilated’ because there is a constant flow of compressed air to the diving suit.  The air comes through the hose from the surface.  The excess air exhaled by the diver, rich in carbon dioxide, is eased into the water through the ‘easing valves’ of the suit.

Three-bolt ventilated equipment  (see Figure 37) consists of the following parts: helmet with the breast plate (1) and the jacket (2) that form the diving suit; diving boots (3), diving weights (4), knife (5), signal ring (6), air hose with the telephone cable (7) and a telephone helmet.  

Figure 37.  The main components of the three-bolt ventilated diving equipment:

1 - helmet with the breastplate; 2 – diving jacket; 3 - diving boots, 4 - diving weights; 5 - knife,  6 - signal ring; 7 - air hose with the telephone cable

‘Three-bolt ventilated equipment’ helmet (Figure 38) is necessary to keep a small amount of air for breathing. It is also necessary for the protection of a diver’s head against the action of water and against a possible blow under water.

The helmet is made of sheets of copper 1 mm - 1.5 mm thick.  It is pot-shaped.  The helmet has a flange with openings for bolts. One front and two side ports (windows) are built into the helmet.  The side ports (windows) are attached permanently.  The front port (window) can be removed. 

Ports (windows) are made of thick glass (14 mm) and attached to the helmet by screwed in metal rings with rubber gaskets.  The front port (window) is secured in a metal frame.  The port together with its metal frame is screwed into the helmet using two protruding rods.  The front port is watertight because of a rubber gasket.

Figure 38. Helmet and breastplate of  three-bolt diving equipment:

 1 – ‘pot’ of the helmet; 2 – breastplate,  3 – front port, 4 – side port, 5 – air inlet, 6 – telephone inlet, 7 – head valve, 8 – flanges of helmet and breastplate, 9 – joining bolt, 10 – telephone, 11 – microphone.

Breastplate. The breastplate is used to join the helmet to the jacket and stabilises the helmet on a diver’s shoulders.  It is made of thin sheets of copper.  The breastplate has a flange with three studs-bolts attached to it.  First the flange of the diving jacket is put on the bolts followed by the flange of the helmet.  The flanges are secured with nuts that go on the bolts.  This way the joint becomes watertight.

Air inlet. Air inlet is needed to attach the diving hose to the back part of the helmet (Figure 39).  The inlet is riveted to the helmet.  The joint is carefully soldered (or brazed?).  The inlet is tested for separation with a 200 kg weight.  Such strength is needed to lift a diver by the hose in case the usual way to lift, on a signal end, is for some reason impossible.

Fig. 39. Air inlet

1-     Body of the safety valve with a grate; 2 – rubber valve; 3 – screw with a washer; 4 - body of the air inlet. 

On one end, the air inlet has a coupling for the attachment of a diving hose.  A safety valve is attached to the other end of the air inlet, inside the helmet.  The valve consists of a body (1), rubber valve (2) and a screw with a washer (3).  The rubber valve (2) lies tightly on the valve seat, covering the opening of the seat.  The rubber valve is held onto the seat by the screw with the washer.  The valve lets the air inside the diving suit.  It is a one-way valve.  It protects against the loss of air from the diving suit in case of damage or breakage to the air hose. Therefore, it protects against the lowering of air pressure in the helmet, which would be dangerous for a diver’s health.

An air-directing shield is installed inside the helmet.  The stream of air breaks onto the shield and is directed towards the front of the helmet. 

Telephone inlet is attached to the helmet just as firmly as the air inlet.

Figure 40. Telephone inlet:                          Figure 41.  Head valve:

1 – body; 2 – rubber-sealing bushing;              1 – valve body; 2 – valve plate with stem; 3 –        3 -thrust metal bushing, 4 – lock-nut;                conical spring,   4 – lattice lid; 5 – locking strip;   5 – telephone cable                                              6 – screw;  7 – safety grate; 8 – valve  button                           

The telephone inlet (Fig. 40) consists of the following parts: 1 – body; 2 – rubber-sealing bushing; 3 - thrust metal bushing, 4 – lock nut.  When lock nut  (4) is screwed on, thrust metal bushing (3) presses onto the rubber bushing (2).  This way the inlet is watertight.  The telephone cable (5) is attached to the inside of the helmet and joined to a telephone and a microphone.  The microphone lies on top of the helmet between the right -side port and the front port (window).  It is needed to transmit speech from a diver.  The telephone lies at the back, near the left port (window), at the ear level.  The telephone is for reception of speech that is transmitted from above. The telephone and the microphone are attached to the helmet on their own fittings.

Head valve. (Fig. 41).  The head valve is needed to ventilate the diving suit and to dispose of excess air quickly.  The type of the valve is ‘easing spring-poppet valve of forced action’.  

Valve body (1) is connected to the helmet and works as the seat of the valve.  Valve plate with stem (2) covers the opening of the valve and makes it watertight.  The stem ensures the straight movement of the plate when the valve opens.  Conical spring (3) keeps the valve (2) shut. Lattice lid (4) is screwed onto the valve body.  It protects the valve from possible damage and blockage. Locking strip  (5) with screw (6) stops the lattice lid from unscrewing.  Safety grate (7) protects the valve against dirt coming from inside the helmet. 

By pressing with his head onto valve button (8), the diver from time to time eases off the excess air from the diving suit into the water.

Diving jacket (Fig. 42) protects a diver from the direct action of the surrounding water and prevents injuries in case he comes into contact with sharp objects under water.  The diving jacket is made of three layers of rubberised material.  The outer layer is a strong   rubberised cloth ‘tiftik’.  The inner layer is a thin rubberised padding ‘domestic’.  In the middle, there is a thin layer of natural or silky rubber.  Such composition of the jacket makes it strong and watertight. However, the material is not elastic enough.  It hinders the diver’s movement under water.  Other different, softer materials are used to make diving jackets, e.g. canvas covered with a thin layer of rubber on both sides.

 Fig. 42.  Summer diving jacket of three-bolt equipment:

1 – trousers; 2- cuff, 3 – knee-pad; 4 – pad between the trouser legs, 5 – sleeve, 6 – flange

Fig. 43. Back easing valve:
1 – valve body with its seat and arcs; 2 – rubber valve; 3 – screw with washer; 4 – V-ring; 5 – rubber gaskets; 6 – lattice lid; 7 – locking screw

 The diving jacket is sewn together as one unit with trousers (1) and sleeves (5).  At the top of the jacket, there is rubber flange (6), which joins to the helmet.  On trousers, there are protective kneepads (3), which help reduce wear and tear, and pads between the trouser legs.  There are elastic cuffs (2) on the sleeves of the jacket that stop water getting inside.  The diving jacket with attached gloves instead of cuffs is called ‘winter diving suit’.  It is used to submerge into cold water.  The diving jacket with rubber cuffs is called ‘summer diving jacket’.  It is used when water temperature allows a diver to work with bare hands.

 The diving jackets are made in three sizes: first – small (height of a person 160-165 cm), second – medium (height of a person 166-176 cm) and the third – large (height of a person above 176 cm). 

On the front of the diving jacket, at chest level, there is a front easing valve.  There is another easing valve (back easing valve) on the back of the diving jacket, level with the shoulder blades. These valves are needed to ventilate the diving suit.  The excess air containing carbon dioxide that a diver breathes out is removed through the valves.  By preventing air collecting in the diving suit, the easing valves stop the tearing of the diving jacket and accidental lift of the diver towards the surface due to increased floating ability.

 Back easing valve is shown at Figure 43. Screw with washer (3) attaches rubber valve (2) to the valve body.  Valve body (1) is inserted into the opening of the diving jacket.  Lattice lid (6) is screwed onto the valve body.  The lattice lid protects the outside of the valve from possible damage or blockage and attaches it to the diving jacket.  To tighten the joint of the valve and the diving jacket rubber gasket (5) is inserted. Rubber gasket (5) is held in place by V-ring (4).  Locking screw (7) is needed to stop the lattice lid from unscrewing. 

 When there is excess air in the diving suit and its pressure exceeds the water pressure at the valve level, rubber valve (2) bends outwards. The excess air leaves the diving jacket and enters the water through the opening in the valve seat. When the air pressure in the diving suit falls, the water pressure pushes the rubber valve to the lattice seat and closes the opening. The water, therefore, cannot get into the diving jacket. 

Fig. 44. Front easing valve:
1 - valve body with its seat and arcs; 2 – rubber valve; 3 – screw; 4 - washer; 5 – rubber pads; 6 – V-ring with a bushing; 7 – turning lid; 8 – screws; 9 – washer.

 Front easing valve.  Unlike the back easing valve, the front easing valve has a special mechanism that helps to shut off the valve and stop it from working.  This allows collecting air in the diving suit to increase floating ability if necessary.

Front easing valve of the diving jacket (Fig. 44) consists of the same parts as the back easing valve except, instead of the lattice lid of the front valve, there is a V-ring with bushing and a turning lid.  The V-ring with bushing and the turning lid both have holes that are ‘in register’ (open) when the lid is turned clockwise.  The holes are closed when the lid is turned anti-clockwise.  The front easing valve of the diving jacket works in the same way as the back easing valve. 

Russian diving physician F.I. Shidlovsky invented the easing valve.  Creation of the easing valve was an important improvement in ventilated diving equipment.  Firstly, easing valves help the air exchange in the diving suit.  Secondly, they speed up the removal of the carbon dioxide, which a diver breathes out, from the diving suit.  

If a diving jacket has easing valves the fresh air coming into the diving suit displaces the air rich in carbon dioxide, which leaves through easing valves. The diver, therefore, uses the head valve less frequently.

Both easing valves are one-way valves of ‘rubber-turning’ type.  The easing valves have a drawback:  they do not fit the valve seats very tightly.  As a result, water gets into the diving jacket.  Because of that, the new version of the easing valve of the diving jacket was introduced – easing valve with ‘a rubber petal’.

 To improve ventilation of the diving suit it is possible to install two valves on the back of the diving jacket.

 Diving boots (Fig. 45) give diver stability under water by stopping him from turning upside down.  Additionally, diving boots protect diver’s legs from possible knocks.  They also protect ends of trousers of the diving jacket from damage.

 Fig. 45. Diving boots: 1 – canvas upper; 2 – lead soles; 3 - wooden insoles; 4 – metal end; 5 – shoelaces. 

Fig. 46.  Diving weights: 1 – weights; 2 – bottom brace; 3 – top braces.

 The uppers of the diving boots are made of leather or canvas (1).  The boots have lead soles (2), wooden insoles (3), metal end (4) and shoelaces (5).  Shoelaces or straps are needed to keep the boots on diver’s feet securely.  The weight of two diving boots is around 24 kg. Sometimes diving boots are made with cast iron soles.  However, such boots are less suitable for under water work because they slip when a diver walks on a hard surface (e.g. metal deck of a sunken ship, stones etc).

 Diving weights  (Fig. 46) are used to compensate the floating ability of a diver during the descent into water.  When the weights are spread correctly according to the height, a diver is in a stable and comfortable position.  

There are two weights – front and back.  They are made of lead or cast iron.  The weight of each of them is 16 - 18 kg.  They are connected with special hemp ropes that are called ‘braces’.  Using the two top braces, weights are arranged on diver’s shoulders in such a way that the top part of the front weight touches the breastplate and the bottom part of the back weight is level with the small of the back.  The bottom brace goes between the legs of a diver and joins both weights from the bottom.  It, therefore, stops the helmet with the breastplate from lifting above the diver’s head if there is excess air in the diving suit.  If the bottom brace is broken, the helmet can lift up so high that the diver will not be able to reach the button of the head valve and ease excess air out.  Rods with rings attach braces to weights.  One shoulder brace has a clasp.

 Signal end is needed to transmit signals to a diver.  It is a hemp rope 50-75 mm thick that was tarred.  It can be up to 100 m long.  Working strength of such a rope is 400-600 kg.  There loops (or rings?) on both sides of the rope.  With the help of one of them the signal end is tied in a loop on the diver’s waist. (Diver is dressed in all the equipment).  The other   loop (or ring) is attached to the eyebolt on the deck of the diving boat.  The signal end has to be attached this way to make sure that it does not fall into the water if it is pulled out of hands of a supporting diver who receives signals from a diver under water. 

 The signal end has to meet strict safety regulations.  It should not have weak worn out areas.  Knots and splices are not allowed. The signal end should be made of strong whole rope.  There are special signals that provide communication between a diver and a surface crew through the signal end.  There are nine special signals to a diver and eleven special signals from a diver.  Meaning of these signals is shown in Table 2. 

 Table of special signals                                                                         Table 2

 Signals to a diver 

Signals from a diver

 A person who received a signal should repeat it.

 Diving hose.  The diving hose is used to provide air to a diving suit from a pump or from an air-distributing shield of a diving compressor.  There are three types of hoses: ‘without a spiral’, ‘spiral’ and ‘ light  without a spiral’.

 Figure 47.  Non-spiral diving hose

1  - inner layer of rubber; 2 – cloth layer; 3 – outside rubber layer.

Fig. 48. Spiral diving hose: 1 – rubber; 2 – cloth layers; 3 – spiral.

 Hose without a spiral  (Fig. 47) is a strong solid tube.  Its inside diameter is 14mm and the outside diameter is 30 mm.  Inner and outer layers of the hose are made of rubber. They are smooth.  Between the inner and the outer layers there is a layer of rubberized cloth.  All the layers are joined together by the rubber vulcanization process.  The colour of the outside surface of the hose is either very light or red, so it can be seen easily in the water.  The hose without a spiral is used for work at small depths.  The light hose without a spiral is also used for diving.  Its inner diameter is 8.5 mm and the outer diameter is 22 mm.

 Spiral hose (Fig. 48) is used for descents to large depths and in cases of strong current. Spiral diving hose is stronger than the one without a spiral.  The difference between the two is that the spiral diving hose has a steel spiral installed between first and second cloth layers.  The inner diameter of the spiral diving hose is 14 mm and the outer diameter is 36 mm.

 Diving hoses are so strong and they can be used to lift a diver if the signal end is damaged or gets entangled.  The diving hoses resist the flattening well when a small weight is pushed against them in the water.  They do not break and maintain inside working pressure well.  Strength of diving hoses is shown in Table 3.

Strength of diving hoses                                  Table 3

Hoses consist of sections 18 – 20 m long.  These sections are joined together by brass hose connectors.  There are two types of hose connectors: connectors that can be dissembled and the ones that cannot be dissembled.  A connector that can be dissembled (Fig. 49) consists of coupling (1), two nipples (2) and two coupling nuts.

Fig. 49.  Hose connector that can be dissembled:

 1 – coupling; 2 – nipple; 3 – coupling nut; 4 – seizing

  The nipple of the hose connector is inserted with some force into the end of the rubber hose.  The hose is then secured on the nipple with two seizings made of copper wire.  If the hose has an inner spiral, then in case of the repeated installation of hose connector, the spiral needs to be pulled out and cut beforehand.  The length of the cut spiral should correspond with the length of the barbed part of the nipple.  Different sections of the hose (with secured nipples and coupling nuts) are joined together with couplings and secured with coupling bolts. 

The diving hose is attached to the air inlet with a coupling nut.  The other end of the diving hose is attached to the air tube of the diving pump or to the coupling of air-distributing shield with a coupling nut as well.

 19.  Improved three-bolt ventilated equipment УBC-50

In 1950 the three-bolt ventilated equipment was improved.  In the helmet (Fig. 50), air and telephone inlets were joined together to form an air-telephone inlet.  The safety valve of rubber-turning type was exchanged for spring-poppet safety valve.  The air-distributing shield was extended to supply air coming into the helmet to the front port.  On the diving jacket, the easing valve of rubber–turning type was exchanged for the ‘combination petal-easing valve’. 

The joining of two inlets into one air-telephone inlet improved the outside contour of the helmet.  It decreased the number of protruding parts.  The helmet manufacture became simpler and cheaper.

Fig. 50 Helmet of diving equipment УBC –50:

1 – air-telephone inlet; 2 – safety spring-poppet valve; 3 – air-distributing shield.

Air-telephone inlet (Fig. 51) has two canals placed one on top of the other.  Telephone cable (6) enters the helmet through the top canal.  Air gets into the helmet through the bottom canal.  The telephone cable is sealed by rubber sealing bushing (4).  Rubber sealing bushing is encircled and secured by thrust metal ring (3) with the help of locking nut (2).  To protect the cable from damage at the spot where it bends near the inlet safety shield (5) is installed.

 Fig. 51. Air-telephone inlet of diving equipment УBC –50: 1 – body of the inlet; 2 – lock-nut; 3 - thrust metal ring; 4 - rubber sealing bushing; 5 – safety shield; 6 – telephone cable; 7 - diving hose; 8 – coupling nut of the diving hose; 9 – safety valve

Fig. 52.  Safety valve of ‘spring-poppet’ type:
 1 – valve body; 2 – poppet valve with a stem; 3 – leather gasket; 4 – leather seal of the valve; 5 – air-distributing shield; 6 – spring; 7 – check nut with split pin

Safety valve of ‘spring-poppet type’ is shown at figure 52.  The body of the safety valve is screwed onto the air inlet and works as the seat of the valve. Leather gasket (3) is needed to seal the valve body.  Spring (6) is put onto the stem of valve (2).  It is secured with check nut (7).  The spring holds the valve shut.  When the pressure in the hose is greater than the pressure inside the diving suit, the valve opens and air goes into the diving suit.  When the pressure in the hose becomes lower than the pressure in a diving suit, the valve closes.  Leather seal (4) is needed to make the valve watertight.

Safety valve of ‘spring-poppet type’ is more reliable than the valve of ‘rubber-turning type’.

Air-distributing shield (5) in the helmet УBC – 50 is extended up to the front port. The stream of fresh air washes a diver’s face and front port.  It protects the front port from fogging.  Therefore, the visibility under water is improved.

Easing valve.  The improved easing valve is installed on the diving suit УBC-50. Unlike the old easing valve of rubber-turning type that frequently let water into the jacket, the new improved valve is more reliable.  Instead of rubber valve the ‘rubber petal’ valve is used.  The ‘rubber petal’ valve does not let water inside the diving jacket.  The new easing valve is shown at Figure 53.

Figure 53. Easing valve of the diving jacket from equipment УBC-50: 1 - valve body with its seat; 2 – rubber petal valve; 3 – pressing plate with stem; 4 – spring; 5 – lattice lid with openings; 6 – screw; 7 – lid with protruding rods; 8 – nut with arcs; 9 – washer; 10 – rubber gasket; 11 - guide bushing.

Valve body with its seat (1) is used to connect all parts of the valve.  The valve body is attached to the diving jacket by nut with arcs (8).  Washer (9) is put under nut (8).  To seal the joint between the valve and the diving jacket, rubber gasket (10) is used.  

When pressure inside the diving suit is higher that the pressure of the surrounding water, pressing plate with stem (3) lifts.  Spring (4) contracts and the excess air leaves the diving suit through petal valve (2).  When the pressure in the diving suit lowers, the plate of the valve (because of the spring) lies on the seat of the valve and presses onto the petal valve.

Lattice lid with openings (5) covers the petal valve from the outside and protects it from damage and blockages.  Guide bushing (11) holds the spring and guides the movement of the stem of the valve. 

Screw (6) attaches the stem of the pressing plate to lid (7).  When turned clockwise, the lid with protruding rods lowers the pressing plate onto the petal valve and stops the easing valve from working.  When the lid is turned anti-clockwise, petal valve is freed.

In 1951, Soviet inventors specialising in diving equipment, Shves and Orlov, suggested an improved version of the head valve that is used in УBC–50 equipment.  During work under water, the old head valve used to occasionally let water into the diving suit when the air was eased out of the helmet.  It happened when a diver was lying down, for example when ‘washing through the tunnels’ under the hull of a sunken ship.  Small particles of silt present in the water used to get onto the working surface of the valve and compromise its water-tightness. 

 Fig. 54. Improved head valve and the diagram showing how it works: 1 – valve body; 2 – poppet valve; 3 – spring;  4 – button; 5 – cup; 6 – rubber-turning valve; 7 – safety grate with slits; 8 – safety grate; 9 – gasket; 10 – locking screw

The structure of the new improved head valve is shown on the figure 54.  It also shows how the valve works.  The improved valve has an extra metal cup (5). ‘Rubber-turning valve’ (6) is attached to it.  The ‘rubber –turning valve’ lets the air from the helmet come out and stops water getting inside the valve.  Such a head valve has double protection from water getting inside the diving suit when the air is eased out of it. 

20.   Twelve-bolt ventilated diving equipment

For work at small depths, the twelve-bolt ventilated equipment is used.  (Fig. 55).  It is mainly used for under-water work in harbours, lakes and rivers at depths no more than 30 m.  Structure of the helmet, breastplate and the flange shape of the diving jacket are different from the three-bolt equipment. 

Fig. 55.  Twelve-bolt ventilated diving equipment.

 Twelve-bolt ventilated equipment helmet (Fig. 56) is attached to the breastplate with a lock with ridges.  The ridges are on the flanges of the helmet and the breast plate. They have screw threads.  When the helmet is attached to the breastplate, the inner ridges of the helmet slid into the outer grooves of the breastplate.  Then the helmet is turned 60 °, and the thread of its flange ridges goes into the thread of the flange ridges of the breastplate.  To make the joint watertight, a gasket is inserted between the flanges of the helmet and the breastplate. 

Figure 56.  Twelve-bolt equipment helmet and breastplate

This type of joint between the helmet and the breastplate in this equipment is very convenient when a diver needs to come up onto the surface frequently.    By turning the helmet 60 °, it can be very quickly taken off a diver, which came up onto the gangway.

Figure 57. Twelve-bolt equipment diving jacket

To stop accidental disconnection between the helmet and the breastplate under water, a special lock – wing nut (thumbscrew) is installed at the back of the helmet flange.  There were cases in diving practice when the helmet got disconnected from the breastplate and the water poured onto the diver.  It happened because the lock was broken or was not screwed right up to the end.  That is why when this equipment is used, it is necessary to screw the wing nut in as far as it will go into the breastplate flange.

The reinforcement strip is soldered (brazed?) onto the breastplate in order to attach the diving jacket.   There are twelve studs in the reinforcement strip placed on equal distance from each other.     The studs together with ‘throw over’ strips are needed to attach the diving jacket to the breastplate.  The ‘throw over’ strips are tightened with wing nuts (thumbscrews).  There are four ‘throw over’ strips: front, back and two top ones.  They are screwed tight to the breastplate.  To put them into the right places, they are marked with first letters of the following words: Передняя – front, Задняя – back, Правая – right, Левая - left.  The joints of ‘throw over’ strips are placed under the wing nuts (thumbscrews).  At these joints, metal washers are placed under the wing nuts.  This way gripping of ‘throw over’ strips and the flange of the diving jacket is evenly distributed around the whole contour of the breastplate.  The joint becomes watertight.

The flange of the diving jacket (Fig. 57) is made of rubber.  It follows the contour of the breastplate and has a big opening.  The big opening allows a diver to put on the jacket easily.

A wide collar made of the jacket’s material is glued to the inside of the flange.  The collar hugs a diver’s neck and stops moisture that condenses in the helmet.  The woollen underwear on a diver does not get wet because of the water dripping from the helmet.  Therefore, a diver feels well and comfortable while working under water.  The rest of the twelve-bolt equipment is the same as the three-bolt equipment. 

When compared with the three-bolt equipment, the twelve-bolt equipment has its merits and drawbacks.  It is easy to put on.  The helmet can be detached from the breastplate quickly when the diver comes onto the gangway for a brief rest without undressing.  The collar protects the diver well from the water that condenses and drips from the helmet.  However, it is difficult to reach full water-tightness of the joint of the jacket with the breastplate and the breastplate with the helmet.  This type of equipment is, therefore, not suitable for work at large depths.