The Scott Air-Pak SCBA is an open-circuit, self-contained breathing apparatus designed to meet the National Fire Protection Association (NFPA) Standard 1981. All components, excluding the air cylinder, were designed and manufactured by Scott Safety. Formerly a division of Tyco International, Ltd., Scott Safety was sold to 3M in 2017. [1]
Other sizes sold are 45, 60 & 75 minute cylinders.
The cylinder and valve assembly is used for storing breathable air under pressure.
The burst pressure for the tri-dimensional burst disk used in the Scott is 4800 psi. Carbon composite cylinders are made up of an aluminum alloy inner shell with carbon composite wraps and epoxy resin. They have a burst pressure of 12,000 psi, 6,500 without the carbon composite wrap. [4]
The valve assembly is the appliance which will make the connection between the cylinder and the hose (which will send the air to a pressure reducer). It is constructed of forged aluminum alloy, and is angled to reduce stress of the connection made between the high-pressure female coupling of the high pressure hose. Newer cylinders contain a "tri lobe, ergonomically designed hand wheel." [5] This hand wheel is a one-way, ratcheting type knob which is a push to close style knob. This protects the user from unwanted accidental shutoff during use.
There is also "an upstream connected frangible disc safety relief device" [5] located on the valve assembly which is also known as the "tri-dimensional burst disk". This burst disk protects the user against a situation where the pressure in the bottle would increase with exposure to heat during a fire. It prevents unwanted failures somewhere else in the bottle. It is set to release at 7200 psi, or 400 °F. It is "tri-dimensional" in that, if it is activated, it would disperse the air from the bottle in three directions so as not to throw the user off his or her balance. [6]
The high pressure male coupling, included in high pressure bottle connections, is set to meet the Compressed Gas Association Standards #346 and #347.
Also included in the assembly are the dual-sided pressure gauge (which reads the cylinder pressure directly from the cylinder), elastomeric bumper (a protective, rubber like stop), and hangar plate (for positive locking attachment of the assembly to the backframe).
The pressure gauge's indicated gas pressure changes with ambient temperature. As temperature decreases, the pressure inside the cylinder decreases. The relationship between the temperature and the pressure of a gas is determined by using the formula PV = nRT. [7] What is particularly important to understand from the formula is that the temperature is in kelvins, not degrees Fahrenheit. Consider the freezing point of water at 32 degrees Fahrenheit (0 degrees Celsius) and compare it to 96 °F (35.6 °C; normal human body temperature is 37 °C). While 96 is arithmetically three times 32, the difference in temperature from a scientific point of view is not threefold. Instead of comparing 32 to 96, temperatures of 273.15 K and 308.71 K should be compared. [8] The actual scientifically valid change in temperature from 32 to 96 °F is by a factor of 1.13 (308.71/273.15), not 3. If an air cylinder is pressurized to 4,500 psi at 96 °F and later the temperature drops to 32 °F, the pressure gauge will indicate 4,000 psi (4,500/1.13). Stated differently, a drop in temperature of 10 degrees Fahrenheit causes a pressure decrease of about 82 psi.
A self-contained breathing apparatus (SCBA), sometimes referred to as a compressed air breathing apparatus (CABA) or simply breathing apparatus (BA), is a device worn to provide breathable air in an atmosphere that is immediately dangerous to life or health. They are typically used in firefighting and industry. The term self-contained means that the SCBA is not dependent on a remote supply of breathing gas. If designed for use under water, it is also known as a Scuba set. When not used underwater, they are sometimes called industrial breathing sets. Unofficial names include air pack, air tank, oxygen cylinder or simply pack, which are mostly used in firefighting.
A bicycle pump is a type of positive-displacement air pump specifically designed for inflating bicycle tires. It has a connection or adapter for use with one or both of the two most common types of valves used on bicycles, Schrader or Presta. A third type of valve called the Dunlop valve exists, but tubes with these valves can be filled using a Presta pump.
A diving cylinder or diving gas cylinder is a gas cylinder used to store and transport high pressure gas used in diving operations. This may be breathing gas used with a scuba set, in which case the cylinder may also be referred to as a scuba cylinder, scuba tank or diving tank. When used for an emergency gas supply for surface supplied diving or scuba, it may be referred to as a bailout cylinder or bailout bottle. It may also be used for surface-supplied diving or as decompression gas. A diving cylinder may also be used to supply inflation gas for a dry suit or buoyancy compensator. Cylinders provide gas to the diver through the demand valve of a diving regulator or the breathing loop of a diving rebreather.
A diving air compressor is a gas compressor that can provide breathing air directly to a surface-supplied diver, or fill diving cylinders with high-pressure air pure enough to be used as a breathing gas. A low pressure diving air compressor usually has a delivery pressure of up to 30 bar, which is regulated to suit the depth of the dive. A high pressure diving compressor has a delivery pressure which is usually over 150 bar, and is commonly between 200 and 300 bar. The pressure is limited by an overpressure valve which may be adjustable.
A pressure vessel is a container designed to hold gases or liquids at a pressure substantially different from the ambient pressure.
Bottled gas is a term used for substances which are gaseous at standard temperature and pressure (STP) and have been compressed and stored in carbon steel, stainless steel, aluminum, or composite bottles known as gas cylinders.
Gas blending for scuba diving is the filling of diving cylinders with non-air breathing gases such as nitrox, trimix and heliox. Use of these gases is generally intended to improve overall safety of the planned dive, by reducing the risk of decompression sickness and/or nitrogen narcosis, and may improve ease of breathing.
A gas cylinder is a pressure vessel for storage and containment of gases at above atmospheric pressure. High-pressure gas cylinders are also called bottles. Inside the cylinder the stored contents may be in a state of compressed gas, vapor over liquid, supercritical fluid, or dissolved in a substrate material, depending on the physical characteristics of the contents. A typical gas cylinder design is elongated, standing upright on a flattened bottom end, with the valve and fitting at the top for connecting to the receiving apparatus.
This is a glossary of firefighting equipment.
Cold inflation pressure is the inflation pressure of tires before the car is driven and the tires(tyres) warmed up. Recommended cold inflation pressure is displayed on the owner's manual and on the placard attached to the vehicle door edge, pillar, glovebox door or fuel filler flap. 40% of passenger cars have at least one tyre under-inflated by 6 psi or more. Drivers are encouraged to make sure their tires(tyres) are adequately inflated, as under inflated tires(tyres) can greatly reduce fuel economy, increase emissions, cause increased wear on the edges of the tread surface, and can lead to overheating and premature failure of the tire(tyre). Excessive pressure, on the other hand, may lead to impact-breaks, decreased braking performance, and cause increased wear on the center part of the tread surface.
Medical gas supply systems in hospitals and other healthcare facilities are utilized to supply specialized gases and gas mixtures to various parts of the facility. Products handled by such systems typically include:
A Cornelius keg is a stainless steel canister (keg) originally used as containers by the soft drink industry. They can be used to store and dispense carbonated or nitrogenated liquids. Cornelius kegs were originally made by Cornelius, Inc.
A cascade filling system is a high pressure gas cylinder storage system which is used for the refilling of smaller compressed gas cylinders. In some applications, each of the large cylinders is filled by a compressor, otherwise they may be filled remotely and replaced when the pressure is too low for effective transfer. The cascade system allows small cylinders to be filled without a compressor. In addition, a cascade system is useful as a reservoir to allow a low-capacity compressor to meet the demand of filling several small cylinders in close succession, with longer intermediate periods during which the storage cylinders can be recharged.
A pony bottle is a small diving cylinder which is fitted with an independent regulator, and carried by a scuba diver as an extension to the scuba set. In an emergency, such as depletion of the diver's main air supply, it can be used as an alternative air source or bailout bottle to allow a normal ascent in place of a controlled emergency swimming ascent. The key attribute of a pony bottle is that it provides a totally independent and redundant source of breathing gas for the diver. The name pony is due to the smaller size, often of only a few litres capacity.
In underwater diving, an alternative air source, or more generally alternative breathing gas source, is a secondary supply of air or other breathing gas for use by the diver in an emergency. Examples include an auxiliary demand valve, a pony bottle and bailout bottle.
Oxy-fuel welding and oxy-fuel cutting are processes that use fuel gases and oxygen to weld or cut metals. French engineers Edmond Fouché and Charles Picard became the first to develop oxygen-acetylene welding in 1903. Pure oxygen, instead of air, is used to increase the flame temperature to allow localized melting of the workpiece material in a room environment. A common propane/air flame burns at about 2,250 K, a propane/oxygen flame burns at about 2,526 K, an oxyhydrogen flame burns at 3,073 K and an acetylene/oxygen flame burns at about 3,773 K.
A potato cannon is a pipe-based cannon that uses air pressure (pneumatic), or combustion of a flammable gas, to launch projectiles at high speeds. They are built to fire chunks of potato, as a hobby, or to fire other sorts of projectiles, for practical use. Projectiles or failing guns can be dangerous and result in life-threatening injuries, including cranial fractures, enucleation, and blindness if a person is hit.
This is a glossary of technical terms, jargon, diver slang and acronyms used in underwater diving. The definitions listed are in the context of underwater diving. There may be other meanings in other contexts.
A gas cabinet is a metallic enclosure which is used to provide local exhaust ventilation system for virtually all of the gases used or generated in the semiconductor, solar, MEMS, NANO, solar PV, manufacturing and other advanced technologies.
The mechanism of diving regulators is the arrangement of components and function of gas pressure regulators used in the systems which supply breathing gases for underwater diving. Both free-flow and demand regulators use mechanical feedback of the downstream pressure to control the opening of a valve which controls gas flow from the upstream, high-pressure side, to the downstream, low-pressure side of each stage. Flow capacity must be sufficient to allow the downstream pressure to be maintained at maximum demand, and sensitivity must be appropriate to deliver maximum required flow rate with a small variation in downstream pressure, and for a large variation in supply pressure, without instability of flow. Open circuit scuba regulators must also deliver against a variable ambient pressure. They must be robust and reliable, as they are life-support equipment which must function in the relatively hostile seawater environment, and the human interface must be comfortable over periods of several hours.