A diving regulator is a pressure regulator that reduces the pressurized breathing gas to ambient pressure and sends it to the diver. The gas may be air or any of the various special respiratory gases that are mixed. The gas may be supplied from a scuba cylinder carried by a diver or through a hose from a compressor or a high pressure storage cylinder on the surface in a surface-supplied dive. The gas pressure regulator has one or more valves in series which reduces the pressure from the source, and uses downstream pressure as feedback to control the flow rate and thereby the pressure applied, lowering the pressure at each stage.
The terms "regulator" and "demand valve" are often used interchangeably, but the demand valve is a regulator that only delivers gas while the diver inhales and reduces the gas pressure to the ambient. In a single hose regulator, the demand valve is the second stage, which is either held at the mouth of the diver by a spokesperson or attached to a mask or full-face helmet. In twin hose regulators, the demand valve is included in the regulator body which is usually mounted directly to the cylinder valve or outlet manifold.
The pressure reduction manager is used to control the pressure of gas delivery supplied to free flow helmets, where the flow is continuous, to maintain the downstream pressure provided by the exhaust ambient pressure and the flow resistance of the delivery system (especially umbilical) and not affected by the dive breathing. The gas evaporation system uses a third type of regulator to control the flow of gas released to the re-hose. The rebreather system can also use regulators to control fresh gas flow, and the demand valve, known as auto fastening valve, to maintain volume in the respiratory loop during down.
The performance of the regulator is measured by cracking pressure and respiratory work, and the capacity to provide respiratory gas at peak inspiratory flow rates at high ambient pressure without excessive pressure drop. For some applications the capacity to provide high flow rate at low ambient temperature without disruption due to freezing is important.
Video Diving regulator
Destination
The dive regulator is a mechanism that reduces the pressure of the respiratory gas supply and provides it for the diver around the surrounding pressure. Gas can be provided on demand, when the diver breathes, or as a constant stream through the diver inside the helmet or mask, from where the diver uses what is needed, while the rest goes to waste.
The gas can be given directly to the diver, or to the rebreather circuit, to replace the gas used and the volume change due to the depth variation. Gas supply may come from a high pressure scuba cylinder carried by a diver, or from a surface supply through a hose connected to a compressor or storage system.
Maps Diving regulator
Operation
Requirements
Both free-flow and demand regulators use mechanical feedback from downstream pressure to control valve opening which controls the flow of gas from the upstream, high pressure, downstream side, low pressure of each stage. The flow capacity should be sufficient to allow downstream pressure to be maintained at maximum demand, and sensitivity should be appropriate to provide the required maximum flow rate with minor variations in downstream pressure, and for large variations in supply pressure. The open scuba regulator circuit must also transmit against variable ambient pressure. They must be strong and reliable, because they are life-support equipment that must function in a relatively unfriendly environment (seawater).
Mechanism
The diving regulator uses a mechanically operated valve. In most cases there is ambient pressure feedback to the first and second stages, unless it is avoided to allow constant mass flow through the hole in the rebreather, requiring constant upstream pressure.
Type
Open circuit request valve
A request valve detects when a diver starts breathing and supplies a diver with gas breath at ambient pressure. This is done by a mechanical system that connects the pressure differential sensor (diaphragm) to the open valve to a level proportional to the diaphragm diaphragmic displacement. The pressure difference between the inside of the funnel and the ambient pressure outside the diaphragm required to open the valve is known as the crack pressure. This crack pressure difference is usually negative but may be slightly positive on the positive pressure regulator (the regulator maintaining the pressure inside the funnel, mask or helmet, which is slightly larger than the ambient pressure). Once the valve is open, the gas flow must proceed at the smallest stable pressure difference that can be made when the diver inhales, and should stop immediately after the gas flow stops. Several mechanisms have been designed to provide this functionality, some of which are very simple and powerful, and others are somewhat more complex, but more sensitive to small pressure changes.
The demand valve has a space, which in normal use contains respiratory gas at ambient pressure. A valve supplying medium pressure gas can vent into space. Either the funnel or full face mask is connected to the room for the diver to breathe from. Funnels can be directly combined or connected to a flexible low pressure hose. On one side of the room is a flexible diaphragm to control the operation of the valve. The diaphragm is protected by a cover with a hole or a gap where water outside can enter freely.
When the diver starts to inhale, the removal of gas from the casing lowers the pressure inside the chamber, and external water pressure moves the diaphragm into the lever operation. It lifts the valve from its seat, releasing the gas into the cubicle. The inter-stage gas, at about 8 to 10 bar (120 to 150 psi) above ambient pressure, expands through the valve opening as the pressure is reduced to ambient and supplies the diver with more gas to breathe. When the diver stops breathing the filling room until the external pressure is balanced, the diaphragm returns to its resting position and the valve release lever to be closed by the valve springs and the gas flow stops.
When the diver blows, a one-way valve (made of flexible airtight material) flexs outward under the breathing pressure, letting the gas out of the room. They close, make a seal, when breathing stops and the pressure inside the room is reduced to ambient pressure.
Most of the open circuit demand valves, which means that exhaled gas is discharged into the surrounding environment and is lost. Return valves can be attached to the helmet to allow the used gas to be returned to the surface for reuse after removing carbon dioxide and forming oxygen. This process, referred to as "push-pull", is technologically complex and expensive and is only used for commercial dives in the heliox mix, where savings on helium compensate for system costs and complications, and to dive in contaminated water. , where the gas is not reclaimed, but the system reduces the risk of contaminated water leaks into the helmet via the exhaust valve.
Flow-free flow regulator
These are commonly used in the supply of diving surfaces with free flow masks and helmets. They are usually a manually controlled, manually controlled industrial gas regulator in a gas panel on the surface to the pressure required to provide the desired flow rate to the diver. Free flow is usually not used in scuba equipment because of high gas flow rates are inefficient and wasteful.
Flow flow constant
In a constant flow regulator, the first stage is a pressure regulator that provides a constant reduced pressure, and the second stage is a plain on/off valve. This is the earliest type of breath controller. Divers should open and close the supply valve to regulate the flow. The constant flow valve in the open circuit of the breathing set consumes less economical gas than the demand valve regulator due to the gas flow even when not needed. Prior to 1939, open circuit series and open industry with constant-flow regulators were designed by Le Prieur, but were not used in general because of the very short duration of dives. Design complications result from the need to place a second stage flow control valve where it can be easily operated by divers.
Retrieve the regulator
The cost of respiratory gas containing high helium fractions is an important part of the cost of deep dive operations, and can be reduced by restoring respiratory gas for recycling. The reclamation helmet is fitted with a turning line inside the umbilical diver gas, and the gas is exhaled into this hose through the reclamation regulator, which ensures that the gas pressure in the helmet does not fall under ambient pressure. Gas is processed on the surface in a helium reclamation system by filtering, rubbing and pushing into storage cylinders until needed. Oxygen content can be adjusted when needed. The same principle is used in the built-in respiratory system used to vent oxygen-rich gas treatments from the hyperbaric chamber, although they are not generally reclaimed. The flow valve is provided to allow the diver to manually switch to an open circuit if the reclamation valve malfunctions, and the pressure drop valve allows water to enter the helmet to avoid pressure if the reclamation valve fails suddenly, allowing the diver's time to switch to the open circuit unscathed.
Reclaim regulators are also sometimes used for hazmat diving to reduce the risk of backflow through the exhaust valve into the helmet. In this application there will be no underpesssure flood valve, but pressure difference and pressure risk is relatively low.
Internal breathing system
The BIBS regulator has a two-stage system on divers that resembles a reclamation helmet, although for this application, the outlet regulator discharges the exhaled gas through the hose out into the atmosphere outside the hyperbaric space.
rebreather regulator
The rebreather system used for diving recycles most of the respiratory gas, but is not based on the demand valve system for its main function. In contrast, the respiratory loop is carried by the diver and remains at ambient pressure when used. The regulators used in scuba rebrows are described below.
Automatic toning valves (ADVs) are used in rebreather to add gas to the loop to compensate automatically for volume reduction due to pressure increase with greater depth or to make the gas lost from the system by the diver exhale through the nose while cleaning the mask or as a method of flushing loop. They are often equipped with a cleaning button to allow for manual flushing of loops. ADV is almost identical in construction and function to the open circuit request valve, but it does not have a flue valve. Some semi-closed passive rebreathers use ADV to add gas to the loop to compensate for a portion of the gas released automatically during the respiratory cycle as a means of maintaining an appropriate oxygen concentration.
The bailout valve (BOV) is an open-circuit demand valve built into the rebreather funnel or any other part of the respiratory loop. This can be isolated while divers use rebreather to recycle respiratory gas and open while at the same time isolating the respiratory loop when the problem causes the diver to save out into the open circuit. The main distinguishing feature of BOV is that the same funnel is used to open and close the circuit, and the diver does not have to close the Dive valve, remove it from their mouth, and find and insert the bailout request valve in order to exit to the open circuit. While expensive, these important step reductions make BOV integrated as a significant security advantage.
The constant flow constant flow valve is used to supply a constant flow of fresh gas to the active semi-closed rebreather to recharge the gas used by the diver and to maintain a constant composition around the loop mix. Two main types are used: fixed and adjustable holes (usually needle valves). The constant mass flow valve is usually based on a gas regulator isolated from the ambient pressure so as to provide an adjusted absolute pressure output (not compensated for ambient pressure). This limits the range of depth to which a constant mass flow is permitted through a hole, but provides a relatively predictable gas mixture in the respiratory loop. Excess pressure relief valve in the first stage is used to protect the output hose. Unlike most other diving regulators, this does not control the downstream pressure, but they regulate the flow rate.
The manual and electronically controlled clamp valve is used on manually and electronically controlled manual and electronic controlled rebreathers (mCCR, eCCR) to add oxygen to the loop to maintain the set-point. Manually or electronically controlled valves are used to release oxygen from the standard first-stage regulator outlet into the respiratory cycle. Excess pressure relief valve in the first stage is needed to protect the hose. Strictly speaking, these are not pressure regulators, they are flow control valves.
History
The first recorded demand valve was discovered in 1838 in France and was forgotten in the next few years; other applicable demand valves were not found until 1860. On November 14, 1838, Dr. Manuel ThÃÆ' Â © odore Guillaumet from Argentan, Normandy, France, filed a patent for twin-hose demand regulators; The diver provided air through the pipe from the surface to the demand valve mounted on the back and from there to the funnel. The gas exhaled out to the side of the head through the second hose. The equipment was demonstrated and investigated by the French Academy of Sciences committee:
On June 19, 1838, in London, William Edward Newton filed a patent (no 7695: "Diving apparatus") for a diaphragm-activated twin-hose diaphragm valve. However, it is believed that Mr. Newton merely filed a patent on behalf of Dr. Guillaumet.
In 1860 a mining engineer from Espalion (France), BenoÃÆ'®t Rouquayrol, found a request valve with an iron air reservoir to let miners breathe in a flooded minefield. He called his invention rÃÆ' Â © gulateur ('regulator'). In 1864 Rouquayol met with French Imperial Navy officer Auguste Denayrouze and they worked together to adapt the Rouquayrol regulator for diving. The Rouquayrol-Denayrouze apparatus was mass-produced with several interruptions from 1864 to 1965. In 1865 it was obtained as standard by the French Imperial Navy, but was never fully accepted by French divers for lack of safety and autonomy.
In 1926, Maurice Fernez and Yves Le Prieur patented the hand-controlled constant flow regulator (not the request valve), which used a full face mask (air coming out of the mask in a constant stream).
In 1937 and 1942, the French inventor, Georges Commeinhes of Alsace, patented the dive demand valve supplied with air from two gas tubes through a full face mask. Commeinhes died in 1944 during the liberation of Strasbourg and his discovery was soon forgotten. The Commeinhes request valve is an adaptation of the Rouquayoul-Denayrouze mechanism, not a cousin of Cousteau-Gagnan tools.
It was not until December 1942 that the demand valve was developed into a widely accepted form. This happened after the French naval officer Jacques-Yves Cousteau and engineer ÃÆ' â € ° Gagnan miles met for the first time in Paris. Gagnan, employed at Air Liquide, has shrunk and adapted the Rouquayrol-Denayrouze Regulator used for gas generators after severe fuel restrictions due to the German occupation of France; Cousteau suggested it was adapted for diving, which in 1864 was his original destination.
Single-hose regulator, with mouth of the demand valve supplied with medium pressure gas from the first installed cylinder valve, was created by Australian Ted Eldred in the early 1950s in response to patent restrictions and Cousteau-Gagnan equipment stock shortages in Australia.. In France, 1955, patents were taken by Bronnec & amp; Gauthier for single hose regulators, then manufactured as Cristal Explorers. Over time, the convenience and performance of improved hose regulators will make them industry standards. Performance is continuously improved with little improvement, and adaptation has been applied to rebreather technology.
The single hose regulator is then adapted to the surface provided by diving in a lightweight helmet and full face mask in the tradition of the Rouquayrol-Denayrouze equipment to save on gas usage. In 1969, Kirby-Morgan had developed a full face mask - Bandmask KMB-8 - using a single hose regulator. It was developed into Kirby-Morgan SuperLite-17B in 1976
Secondary demand valve (octopus), submersible pressure gauge and low pressure inflator hose are added to the first stage.
In 1994, the reclamation system was developed in a joint project by Kirby-Morgan and Divex to recover an expensive helium mixture during deep surgery.
Mechanisms and functions
The parts of the regulator are described as the main functional groups in the downstream sequence as follows: gas flow from the cylinder to the last use and accessories that are not part of the main functional components but are commonly found in contemporary regulators. Some interesting historical models and components are described in the next section.
Two-axial two-stage circuit opening request regulator
Most contemporary dive regulators are two-stage one-hose regulators. They consist of a first-stage regulator, and a second-stage demand valve. The medium pressure hose connects these components to air transfer, and allows relative movement within the limits of the length and flexibility of the hose. Other intermediate-pressure hoses provide optional additional components.
First stage
The first stage of the regulator is attached to the cylinder or manifold valve through one of the standard connectors (Yoke or DIN). This reduces cylinder pressure to medium pressure, typically about 8 to 11 bar (120 to 160 psi) higher than ambient pressure, also called interstage pressure, medium pressure or low pressure. The respiratory gas is then supplied to the second stage through the hose.
The first stage balanced control automatically maintains a constant pressure difference between interstage pressure and ambient pressure even when the tank pressure drops with consumption. A balanced regulatory design allows the first-stage orifice to be as large as required without causing any performance degradation as a result of changes in tank pressure.
The first stage generally has some low-pressure outlets (ports) for second-stage regulators, BCD inflators and other equipment; and one or more high-pressure outlets, allowing a submerged pressure gauge (SPG) or gas-integrated submarine to read cylinder pressure. The valve can be designed such that a low pressure port is specified "Reg" for the second main stage regulator, as it allows for higher flow rates to provide less respiratory effort at maximum demand. A small number of manufacturers have produced regulators with hoses and port diameters larger than the standard for this main outlet.
The mechanism in the first stage can be a diaphragm or piston type. Both types can be balanced or unbalanced. The unbalanced regulator has a cylinder pressure pushing the first upstream valve of the closed phase, which is opposed by the intermediate stage pressure and the spring. When the cylinder pressure falls, the closing force becomes less, so the adjusted pressure increases at the lower tank pressure. In order for this pressure to keep rising within acceptable limits, the size of the high pressure hole is limited, but this decreases the total flow capacity of the regulator. A balanced control maintains approximately the same breathing ease at all depths and pressures, using a cylinder pressure to indirectly oppose the opening of the first stage of the valve.
Piston-type first stage
Some of the first stage piston type components are easier to make and have a simpler design than the diaphragm type. They may require more careful care as some internal moving parts may be exposed to water and contaminants in the water.
The piston in the first stage is rigid and acts directly on the valve seat. Pressure in the medium pressure chamber drops when the diver inhales from the second stage valve, this causes the piston to lift from the stationary valve seat as the piston slide into the medium pressure chamber. The open valve now allows high pressure gas to flow into the medium pressure chamber until the pressure in the chamber is increased enough to push the piston back to its original position against the cradle and thus close the valve.
First stage diaphragm type
The first stage of the type diaphragm is more complex and has more components than the piston type. Their design makes them particularly suitable for diving in cold water and working in saltwater and water containing high suspended particles, mud sediments, or other contaminants, since the only part exposed to water is the valve opening and diaphragm springs, all the parts others are sealed from the environment. In some cases the diaphragm and the spring are also closed from the environment.
The diaphragm is a flexible cover for medium pressure chamber (medium). When the diver consumes the gas from the second stage, the pressure falls in the medium pressure chamber and the diaphragm changes shape into pushing the valve lifter. This opens a high pressure valve that allows gas to flow past the valve seat into the medium pressure chamber. When the diver stops breathing, the pressure in the medium pressure chambers rises and the diaphragm returns to its neutral flat position and no longer presses the valve lifter that closes the flow until the next breath is taken.
Balancing
If the regulator stage has an architecture that compensates for changes in upstream pressure on the moving parts of the valve so that the supply pressure changes do not affect the force required to open the valve, the phase is described as being balanced. Upstream and downstream valves, first and second stages, and diaphragm and piston operations can be balanced or unbalanced, and a full description of a stage will determine which of these options apply. For example the regulator may have the first stage of piston balanced with the second stage downstream balanced. Both balanced and unbalanced pistons of the first stage are quite common, but the first stage of the diaphragm is most balanced. Balancing the first stage has a greater overall effect on regulator performance, since the variation in supply pressure from the cylinder is much greater than the variation in interstage pressure, even with the unbalanced first stage. However the second stage operates at a very small pressure difference and is more sensitive to supply pressure variations. Most of the top regulators have at least one balanced stage, but it is not clear that balancing these two stages makes a noticeable difference with performance.
First stage regulator connection to cylinder valve or cylinder manifold
In the scuba open circuit circuit, the first stage regulator has A-clamp, also known as yoke or international connection, or DIN fitting to connect it to the diving cylinder pillar valve. There are also European standards for scuba regulator connectors for gas other than air.
Yoke valves (sometimes called A-clamps of their shape) are the most popular regulatory connections in North America and some other countries. They clamp the opening of a high-pressure inlet from the regulator against the opening of the cylinder valve opening, and are sealed by O-ring in the groove on the contact face of the cylinder valve. User screw clamps in place of finger-tight to withstand the metal surface of the cylinder valve and the first-stage regulator in contact, compressing the o-ring between the radial face of the valve and the regulator. When the valve is opened, the gas pressure presses the O-ring against the outer cylinder surface of the groove, completing the seal. Divers should be careful not to shake the yoke too tightly, or it may prove impossible to remove without a tool. Conversely, failing tightening can reasonably lead to O-ring extrusion under pressure and large respiratory gas loss. This can be a serious problem if it happens when the diver is at depth. Yoke fittings are rated up to a maximum of 240 bar working pressure.
DIN fittings are a type of screw connection directly to the cylinder. DIN systems are less common throughout the world, but have the advantage of withstanding a larger pressure, up to 300 bar, allowing the use of high pressure steel cylinders. They are less susceptible to blow an O-ring seal if it knocks on something when in use. DIN equipment is standard in most of Europe and is available in most countries. DIN installation is considered safer and therefore safer by many technical divers.
The available adapter allows the first stage DIN to be attached to the cylinder with a yoke fitting valve, and for the first yoke stage to be mounted to the DIN cylinder valve.
Most current cylinder valves are of the K-valve type, which is a manually operated and manually operated on-off valve. In the mid-1960s, the J-valve was widespread. A valve-containing valve operated with a spring that limits or closes the flow when the tank pressure drops to 300-500 psi, causing respiratory resistance and warning the diver that it is very low in the air. Air reserves are released by pulling the spare lever on the valve. J-valves are not favored by the introduction of pressure gauges, which allow divers to track their underwater air, mainly because the valve type is susceptible to unintentional accidental air release and increases the cost and valve service. A j-valve is sometimes still used when work is done in very poor visibility so that the pressure gauge can not be seen, even with light.
Hose interstage
Medium (medium) pressure hoses are used to carry respiratory gas (usually between 8 and 10 bar above ambient) from the first stage regulator to the second stage, or the demand valve, held in the mouth by the diver, or attached to a full face mask or a diving helmet. The standard interstage hose is 30 inches (76 cm) long, but 40 inches (100 cm) hose is standard for Octopus regulators and the 7 foot (2.1 m) hose is popular for technical dive, especially for cave penetration and accidents where space constraints may it is necessary to swim in one file while sharing the gas. Other lengths are also available. Most low-pressure ports are threaded 3/8 "UNF, but some regulators are marketed with one UNF 1/2 port" designated for the main request valve. High pressure ports are almost exclusively 7/16 "UNF. There is no possibility to connect the hose to the wrong pressure port.
Second or second valve
Upstream valve
In the upstream valve, the moving part works against the pressure and opens the direction opposite to the gas stream. They are often made as tilt-valves, which are mechanically very simple and reliable, but not adjustable for fine tuning.
If the first phase is leaked and the inter-stage over-pressurizes, the second stage downstream valve opens automatically generates "freeflow". With an upstream valve, over-pressurization results can be a blocked valve. This will stop the supply of respiratory gas and may cause a broken tube or other second-stage valve failure, such as a valve that buoys a buoyancy device. When the second stage tilt valve is used, the relief valve shall be inserted by the manufacturer in the first-stage regulator to protect the middle hose.
If the breaker valve is installed between the first and second stages, as found in the scuba bailout system used for commercial dive and in some technical dive configurations, the demand valve will normally be isolated and can not function as a release valve. In this case the overpressure valve should be fitted to the first stage if not already have it. Because very few regulators of contemporary scuba regulator (2016) stage are fitted with pressure relief valves, they are available as screwable aftermarket accessories to any low pressure port available in the first stage.
Upstream valve
Most modern demand valves use downstream rather than upstream valve mechanism. In the downstream valve, the moving part of the valve opens in the same direction as the gas stream and remains closed by the spring. The usual downstream valve form is a spring-loaded poppet with sealed hard elastomer seats against a metal "crown" that can be adjusted around the entrance. The little one is lifted away from the crown by a lever operated by the diaphragm. There are two commonly used patterns. One of them is the classic pull pull arrangement, in which the driving lever enters the end of the valve shaft and is held by the nut. Each deflection of the lever is converted into an axial pull on the valve shaft, lifting the seat from the crown and allowing the air to flow. The other is a poppet barrel arrangement, where the little one is confined in a tube that crosses the regulator body and the lever operates through the slot on the side of the tube. The far end of the tube can be accessed from the side of the chassis and the spring voltage adjustment screw can be mounted for the limited diver's control of the crack pressure. This arrangement also allows relatively simple pressure balancing of the second stage.
The downstream valve will serve as an excess pressure valve when the inter-stage pressure is raised sufficiently to overcome the pre-loaded spring. If the first stage is leaked and the inter-stage over-pressurizes, the second-stage down valve opens automatically. if leakage is bad, it can produce "free flow", but slow leakage will usually cause intermittent "pop" from the DV, as pressure is released and slowly rebuild.
Servo controlled valve
Some demand valves use small, sensitive pilot valves to control the opening of the main valve. Poseidon Jetstream and Xstream and Oceanic Omega the second stage is an example of this technology. They can produce very high flow rates for small pressure differences, and especially for relatively small crack pressures. They are generally more complicated and expensive for service.
Disposal valve
The exhaust valve is required to prevent the diver from inhaling the water, and to allow negative pressure differences to be induced over the diaphragm to control the demand valve. The exhaust valves must operate at very small pressure differentials, and cause little resistance to flow as cheaply as possible, without being troublesome and large. Elastomeric fungi valves serve the purpose adequately, although duckbill valves are also common in twin hose regulators. Where it is important to avoid leaks back to the regulator, such as when diving in contaminated water, a two-set valve system in series can reduce the risk of contamination. A more complex option that can be used for helmets provided on the surface, is to use a reclaimed exhaust system that uses a separate flow regulator to control the exhaled exhaust in a specific umbilical hose.
Exhaust manifold
The exhaust manifold (exhaust, exhaust cover, whiskers) is the channel that protects the exhaust valve (s) and diverts the exhaled air to the sides so it does not swell on the diver's face and obscures the view. This is not necessary for twin hose regulators because they drain the air behind the shoulder.
A standard installation in the second stage of the second hose, whether held and built into a full face mask or a request helmet, is a cleaning switch, which allows the diver to manually deflect the diaphragm to open the valve and cause airflow into the casing. This is usually used to clean the casing or face mask full of water if it has been flooded. This will often happen if the second stage is dropped or removed from the mouth while under water. This is a separate section mounted on the front cover or cover can be made flexible and serves as a cleaning button. Depressing the cleaning button presses the diaphragm directly over the demand valve lever, and the movement of this lever opens the valve to release air through the regulator. The tongue can be used to block the funnel during cleaning to prevent water or other substances in the regulator from being blown into the air passage of the diver by the air blast. This is very important when cleaning after vomiting through the regulator.
The cleaning button is also used by recreational divers to inflate a delayed surface marking buoy or lift the bag. Whenever the cleaning button is operated, the diver must be aware of the potential for free flow and ready to deal with it.
User customizable flow changer
It may be desirable for divers to have control over the flow characteristics of the demand valve. The adjustable aspect is usually the crack pressure and feedback from the flow rate to the internal pressure of the second stage housing. The inter-stage pressure of the requested breathing apparatus on the surface is controlled manually on the control panel, and does not automatically adjust to ambient pressure in the way that most first-stage scuba do, since this feature is controlled by feedback to the first stage of ambient pressure. It has the effect that the crack pressure from the surface provided the demand valve will be slightly different from the depth, so some manufacturers provide manual adjustment buttons on the residential side of the demand valve to adjust the spring pressure on the down valve, which controls the cracking pressure. This knob is known by commercial divers as "dial-a-breath". A similar adjustment is given to some high-end scuba request valves, to allow users to manually adjust breathing efforts in depth
Scuba-control valves regulated for light breathing (low crack pressure, and low-breathing work) may tend to flow relatively easily, especially if the gas flow in the housing has been designed to help withstand the open valve by reducing internal pressure. The cracking pressure of the sensitive demand valve is often less than the hydrostatic pressure difference between the interior of the house that contains air and water beneath the diaphragm as the funnel is pointed upward. To avoid excessive gas loss due to unintentional valve activation when DV comes out of the mouth of the diver, the second stage has a desensitising mechanism that causes some back pressure in the housing, by blocking the flow or directing it inward from the diaphragm.
Scuba request protocol twin circuit
Configuration of "twin", "double" or "two" scuba hose valves is the first in general use. This type of regulator has two large wavy respiratory tubes. One tube is to supply air from the regulator to the funnel, and the second tube delivers the exhaled gas to a point where the ambient pressure is identical to the demand diaphragm, which is released through the one-way valve of the rubber ducks, and out of the hole on the cover. The advantage of this type of regulator is that the bubbles leave the regulator behind the diver's head, increase visibility, reduce noise and generate less burden on the diver's mouth, They remain popular with some underwater photographers and Aqualung released the latest version of Mistral in 2005.
In the original prototype aqualung Cousteau, there is no drain hose, and the air is exhaled out through a one-way valve in the mouth of the spokesman. It worked out of the water, but when he tested the aqualung in the river, Marne's air flowed freely from the regulator before it could be inhaled when the funnel was above the regulator. After that, he installed a second breathing tube. Even with both tubes installed, raising the funnel above the regulator increases the gas pressure provided and decreases the funnel reducing the applied pressure and increasing the respiratory resistance. As a result, many aqualung divers, when they snorkel on the surface to save air as they reach the dive site, place the hose beneath the arm to avoid the floating funnel that causes free flow.
Ideally the pressure given is equal to the break pressure in the lung diver as it is the human lung adapted to breathe. With the twin hull regulator behind the diver at the shoulder level, the pressure sent varies with diver orientation. if the diver rolls on his back, the air pressure released is higher than in the lungs. Learners limit the flow by using their tongues to close the funnel. When the cylinder pressure starts to decrease and the air demand effort increases, the roll to the right side makes the breath easier. The funnel can be cleaned by lifting it above the (shallower) regulator, which will cause a free flow.
The twin hose regulators have been replaced almost entirely by single hose regulators and have become obsolete for most of the dives since the 1980s.
The original double-hose regulators usually do not have ports for accessories, although some have high pressure ports for submersible pressure gauges. Some models then have one or more low-pressure ports between stages, which can be used to supply a direct feed for inflation or BC inflation and/or secondary single-hose request valve, and a high pressure port for a submersible pressure gauge. The new Mistral is an exception because it is based on the first stage of Aqualung Titan. which has a regular port set.
The arrangement of twins-hoses with mouthpieces or full-face masks is common in rebreathers, but as part of the respiratory loop, not as part of the regulator. The associated demand valve consisting of a bail-out valve is a single hose regulator.
The twin hose regulator mechanism is packaged in a circular metal housing mounted on the cylinder valve behind the diver's neck. The demand valve component of the two-stage twin-hose regulators is installed inside the same housing as the first-stage regulators, and to prevent free flow, the exhaust valve should be placed at the same depth as the diaphragm, and only a reliable place to do this in a housing same. Air flows through a pair of corrugated rubber hoses to and from the funnel. The supply hose is connected to one side of the regulator body and supplies air to the funnel through the non-return valve, and the exhaled air is returned to the regulator's house on the outside of the diaphragm, also through the non-return valve on the other side of the funnel and usually through the non- Another return at home regulator - often a type of "duckbill".
The non-return valves are usually fitted to the respiratory tube where they are connected to the funnel. This prevents water entering the funnel from entering the inhalation tube, and ensures that it is breathed into a non-returning respiratory tube. This slightly improves air flow resistance, but makes the regulator easier to clean.
Some early twinning hose regulators are one-stage designs. The first stage works in a manner similar to the second stage of the two-stage demand valve, but will connect directly to the cylinder valve and reduce the high pressure air from the cylinder directly to the ambient pressure on demand. This can be done using longer levers and larger diaphragm diameters to control valve movement, but there is a tendency for cracking pressure, and thus breathing work varies when cylinder pressure falls.
Twin-hose without visible valve regulator (fictitious) h4>
This type is mentioned here because it is very familiar in comics and other images, as a two-cylinder aqualung two-cylinder regulator is wrongly drawn, with one wide interval coming out of each cylinder up into the funnel without a clear regulator valve, much more often than the twin hose regulator which is drawn correctly (and often the breathing set is used by combat fighters): see Frogman # Mistakes about frog humans found in public media. It will not work in the real world.
Performance
In Europe, EN 250: 2014 - Respiratory Equipment - Open Circuit Compressed Air Compressed Equipment - Requirements, Testing and Marking define minimum requirements for inhalation of regulator performance, and BS 8547: 2016 defines requirements for demand regulators to be deployed at depths exceeding 50 m. EN 13949: 2003 - Respiratory Equipment - Open Circuit Self-Contained Diving Apparatus for use with Nitrox and Compressed Oxygen - Requirements, Testing, Marking defines requirements for regulators for use with increased oxygen levels.
EN 15333 - 1: 2008 COR 2009 - Respiratory Equipment - Outdoor Circuit Gas Compression Diving Equipment Provided - Part 1: Demand Apparatus. and EN 15333 - 2: 2009 - Respiratory Equipment - Outdoor Circuit Gas Compression Diving Equipment Provided - Part 2: Free Flow Apparatus is the relevant standard for equipment provided on the surface.
EN 14143: 2013 - Respiratory Equipment - Diving Rescue Devices with Self-Dissolution defining minimum requirements for rebreathers.
Cousteau's original twin-hose diving regulator can deliver about 140 liters of air per minute in continuous flow and which is officially considered adequate, but divers sometimes require higher levels and must learn not to "beat the lungs", ie breathing faster than the regulator can give. Between 1948 and 1952 Ted Eldred designed the Porpoise single-hose regulator to supply up to 300 liters per minute.
In the United States Military, the scuba regulator must comply with the performance specifications set forth in Mil-R-24169B.
Various respiratory machines have been developed and used for the assessment of the performance of respiratory equipment. ANSTI Test Systems Ltd. (UK) has developed a test machine that measures the withdrawal and breathing effort in using regulators. The publishing of regulator performance results in ANSTI test machine has resulted in a large performance improvement.
Malfunctions and failure modes
When the gas leaves the cylinder, its pressure decreases in the first stage, becoming very cold due to adiabatic expansion. Where the water temperature is less than 5 Â ° C, the water in contact with the regulator may freeze. If this ice breaks the diaphragm or the piston springs, preventing the valve closing, free flow may occur which can empty the full cylinder in a minute or two, and free flow causes further cooling in the positive feedback loop. Generally the frozen water is in the ambient pressure chamber around the springs that keep the valve open and not moist in the respiratory gas of the cylinder, but it is also possible if the air is not adequately filtered. Modern trends using plastics to replace metal components in regulators encourage freezing because they insulate the inside of a cold regulator of warm water around them. Some regulators are provided with a heat exchange fins in areas where cooling due to air expansion is a problem, such as around the second-stage valve seat on some regulators.
The cold water kit can be used to reduce the risk of freezing inside the regulator. Some regulators come up with this as a standard, and some others can be retrofitted. Sealing the environment from the main diaphragm springs using a soft secondary diaphragm and hydrostatic or silicone, alcohol or glycol/liquid anti-frozen water liquids in sealed spring compartments can be used for diaphragm regulators. Silicone fat in the spring chamber can be used in the first stage of the piston. Poseidon Xstream's first stage isolates the external springs and residential springs from the rest of the regulator, thus less cooled by expanding air, and provides large slots in the housing so that the springs can be warmed by water, thus avoiding the problem of freezing the external spring.
Pressure release valve
The downstream request valve serves as a secure failure for over-pressurization: if the first stage with demand valve malfunction and jammed in the open position, the demand valve will be over-pressurized and will "free flow". Despite presenting divers with an imminent "on the air" crisis, this failure mode allows gas to escape directly into the water without inflating the buoyancy. The effects of unintentional inflation may be to bring diveres quickly to the surface causing various injuries that can be caused by too fast climbing. There are circumstances in which the regulator is connected to a blowing device such as a rebreather breathing bag, buoyant compensator, or dry clothing, but without the need for a demand valve. An example of this is an appropriate set of argon inflation and "off board" or secondary diluent cylinders for rebreathers of closed circuits. When there is no demand valve connected to the regulator, this valve should be equipped with a pressure relief valve, except for valve valves built on top of pressure, so over-pressurization does not inflate the buoyancy device connected to the regulator.
Pressure monitoring
A diving regulator has one or two 7/16 "high-pressure UNF ports upstream of all pressure-reducing valves to monitor the remaining gas pressure in the dive cylinder, provided that the valve is open. There are several types of measuring contents.
Standard submersible pressure gauge
The default setting has a high-pressure hose leading to a customizable pressure gauge (SPG) (also called a content gauge). This is an analog mechanical gauge connected to the first stage with a high pressure hose. It displays with a moving pointer over the dial, usually about 50 millimeters (2.0 inches). Sometimes they are installed in consoles, which are plastics or rubber that hold air pressure gauges and other instruments such as depth gauges, computers and/or compass.
Key gauge
This is a coin-sized analog pressure gauge that is directly attached to a high-pressure port in the first stage. They are compact, have no hanging hoses, and some point of failure. They are generally not used on cylinders mounted on the back because the diver can not see them there when underwater. They are sometimes used on side slung cylinders on the side. Due to its small size, it can be difficult to read a measuring instrument with a resolution of less than 20 bar (300 psi).
Air integrated computer
Some dive computers are designed to measure, display, and monitor the pressure within the dive cylinder. This can be very useful for divers, but if a dive computer fails the diver can no longer monitor its gas reserves. Most divers using a gas-integrated computer will also have standard air pressure gauges. The computer is connected to the first stage with a high pressure hose, or has two parts - a pressure transducer in the first stage and a display on the wrist or console, communicating over a wireless data transmission link; signals are encoded to eliminate the risk of one computer diver picking up signals from other diver transducers or radio interference from other sources.
Secondary query valve (Octopus) id = "Secondary_demand_valve">
As an almost universal standard practice in modern leisure dives, single hose regulators have reserve valves installed for emergency use by diver mates, commonly referred to as octopus due to an extra hose, or secondary request valve. Octopus was discovered by Dave Woodward at UNEXSO around 1965-6 to support free diving efforts Jacques Mayol. Woodward believes that having a safety diver carrying the second two stages would be a safer and more practical approach than a breathing buddy in an emergency. A moderate pressure hose on an octopus is usually longer than a moderate pressure hose on the main demand valve the diver is using, and the request and/or hose valve may be yellow to help locate the site in an emergency. The secondary regulator must be clamped to a diver's harness in a position where it can be easily seen and reached by a potential air divider and divider. Longer hoses are used for comfort while air sharing, so divers are not forced to remain in a relatively awkward position with each other. Technical divers often extend this feature and use a 5-foot or 7-foot hose, which allows divers to swim in one file while air sharing, which may be required in confined spaces inside the wreck or cave.
Secondary demand valve can be a hybrid of the demand valve and compensator valve compensation valve. Both of these types are sometimes called alternative air sources. When the secondary demand valve is integrated with the buoyancy float compensator valve, because of the short inflation valve interval (usually long enough to reach the center of the chest), when the diver runs out of air, the diver with the rest of the air will give the second major stage to the space diver, inflation valve itself.
The demand valve on a regulator connected to a separate independent diving cylinder will also be called an alternative air source as well as an excess air source, as it really does not depend on the primary air source.
Spokesman
A funnel is the part that the user holds in the mouth to create a watertight seal. It is a short short oval tube that lies between the lips, with a matching curved flange between the lips and teeth and gums. At the inner end of the flange there are two tabs with an enlarged tip, which is gripped between the teeth. Most recreational diving regulators are equipped with a funnel. In regulators of twin hoses and rebreathers, "mouthpiece" can refer to the entire assembly between two flexible tubes. A spokesperson prevents a clear greeting, so a full face mask is preferred where voice communication is required.
In some models the funnel scuba regulator also has an outer rubber flange that fits on the outside of the lips and extends into two ropes that bind together behind the neck. This helps keep the funnel in place if the user's jaws relax because of unconsciousness or disturbance. Speech safety flange can also be a separate component. The neck strap attached also allows the diver to keep the regulator hanging under the chin where it is protected and ready for use. The latter funnel usually does not include an external flange, but the practice of using a neck strap has been revived by a technical diver using a bungee or "necklace" surgical rubber that can come out of the funnel without damage if pulled firmly.
Original smearing is usually made of natural rubber and can cause allergic reactions in some divers. This has been overcome by the use of synthetic hypo-allergenic elastomers such as silicone rubber.
Full-face mask or helmet
This is stretching the accessory concept a bit, as it would be equally applicable to calling accessory regulators from full face masks or helmets, but both items are closely connected and generally found to be used together.
Most full face masks and perhaps most of the currently used dive helmets are open-circuit demand systems, using demand valves (in some cases more than one) and supplied from scuba regulators or umbilical surface supplies from surface supply panels using a regulatory surface supply to control primary air pressure and reserve or other respiratory gas.
Diving helmets with light demand are almost always supplied to the surface, but full face masks are used in conjunction with scuba open circuits, scuba covered circuits (rebreathers), and open circuit surfaces provided.
The demand valve is usually firmly attached to a helmet or mask, but there are some full face mask models that have a removable demand valve with a fast connection that allows them to be exchanged underwater. These include Panorama DrÃÆ'¤ger and Kirby-Morgan 48 Supermask.
Buoyancy Compensation and dry suit inflation hose
Hoses can be fitted to low pressure ports of the first stage regulator to provide gas to inflate the buoyancy and/or dry clothing compensator. This hose usually has a fast connector end with an automatic sealing valve that blocks flow if the hose is released from the buoyant compensator or suit. There are two basic styles of connectors, which are incompatible with each other. The high flow rate of the CEJN 221 fittings has a larger opening and allows the gas flow at a level sufficiently fast to be used as a link to the demand valve. This is sometimes seen in combination combined inflator/deflator mechanisms with an integrated secondary DV (octopus), as in the AIR II unit of Scubapro. Low-flow Seatec connectors are more common and are an industry standard for BC inflator connectors, and are also popular in dry clothing, as the limited flow rate reduces the risk of blow-ups if the valve remains open. High flow rate connectors are used by some manufacturers on dry clothing.
A variety of small accessories are available to fit this hose connector. These include interstage pressure gauges, which are used to solve problems and regulate the regulators (not for underwater use), noisemakers, used to attract underwater and surface attention, and valves for inflating tires and floating rubber boats, making air in scuba cylinders available for other purposes.
The instrument console
Also called combo console, this is usually a hard rubber or hard plastic mold that closes the SPG and has a mounting socket for other diver's instrumentation, such as a decompression computer, an underwater compass, a timing meter and/or a depth gauge and sometimes a small plastic slate in where notes can be written either before or during the dive. These instruments will otherwise be taken elsewhere such as being tied to the wrist or forearm or in the pocket and only regulating accessories for ease of transportation and access, and at greater risk of damage during handling.
Automatic shutdown
The auto-closure device (ACD) is the mechanism for closing the incoming opening of the team's inlets
Source of the article : Wikipedia
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