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Types of Valves in Fire Fighting
The first type of valve in fire fighting is called a check valve. These valves are designed to allow water to flow out while preventing backflow of air and extinguishing gas. Check valves are commonly used in plumbing systems, since they prevent fluid from flowing backward when the system is closed. Their primary benefit is that they do not require constant maintenance. However, they have several disadvantages including a tendency to clog easily. When they do clog, they usually cause a major problem.
A second type of valve used in firefighting is a ball valve. Ball valves are designed to open and close rapidly. Because of their rapid operation, they are often used to control fluids at high pressure. Like check valves, ball valves need little maintenance, but the high-pressure environment can cause them to malfunction when exposed to certain chemicals. A third type of valve used in fires is a butterfly valve. Butterfly valves provide many advantages over other types of valves. First, they do not leak. Second, they are inexpensive; they are even constructed using aluminum foil. Finally, they operate slowly enough that they prevent explosions caused by the buildup of pressure inside a tank.
The valves used in fire fighting equipment have many purposes. A single valve may perform several functions at once, such as controlling pressure, directing water, and sealing off leaks. When firefighting equipment operates properly, it prevents water from entering certain rooms while allowing it to flow freely in others. A good valve is able to withstand heat and high pressures without breaking down.
Valve Types
There are two basic types of valves: moving and non-moving. Moving valves move between their open and closed positions when they are operated. Non-moving valves remain in one position until they are manually adjusted. Both types of valves can be powered by air, hydraulic, electric motors, or mechanical means.
Air Powered Valve
An air-powered valve uses compressed air to operate its mechanism. In order for the air-powered valve to work, the water must first be turned off and then turned back on again after the valve is opened. Air-powered valves are commonly used for larger applications where the space taken up by plumbing is not an issue. Air-powered valves offer fast action and low maintenance costs.
Hydraulic Valve
A hydraulic valve uses a fluid (usually oil) under pressure to operate its mechanism. Hydraulic valves require less maintenance than air-powered valves since there is no need for power cords or external air supplies. On the downside, hydraulic valves take longer to actuate than air-powered valves. Hydraulic valves are often used in applications requiring precise timing and a lot of control over the quantity of water delivered.
Electric Motor Valve
Motor driven valves use electrical power instead of pressurized fluids to operate the valve. These valves are sometimes referred to as solenoid valves. Solenoid valves provide the strongest control over the amount of water delivered. However, motor driven valves tend to be expensive to maintain. Electric motor valves generally require that the water supply be shut off before opening the valve, unlike air-powered valves.
Mechanical Valve
Mechanical valves require manual operation. Some examples of these valves include butterfly valves, ball valves, slide valves, plug valves, gate valves, etc. Mechanical valves are often used in smaller systems where there is not enough room for larger valves. These valves do not require electricity or pressurized fluids, and therefore are often favored for use in residential settings. Because of their small size, mechanical valves are relatively inexpensive to replace if damaged.
There are 4 types of valves found in fire fighting equipment; check valves, ball valves, butterfly valves, and diaphragm valves. Check valves seal shut off flow in one direction only. Ball valves have two chambers separated by a spherical metal disk called a valve ball. Butterfly valves have two flaps called wings that open in opposite directions. Diaphragm valves have a flexible disc shaped housing with either a single round hole or slit shaped opening. There are three basic designs of diaphragms found in valves today; flat, spring loaded and poppet (or plug). These different styles of valves offer varying advantages and disadvantages, however they do share some similarities.
Check valves should be placed at the end of any vessel containing flammable liquids. They work best if they are installed upstream of the point where pressure builds up. A good example would be a water tank with a faucet attached. When the hot water comes out of the faucet a little pressure begins to build inside the tank. If we install a check valve at the beginning of the pipe, then the pressure cannot go back into the tank. In this case, the pressure builds up inside the tank until it blows its top, causing a dangerous explosion.
Ball valves and butterfly valves are ideal for many applications. Ball valves are good for use with liquid-liquid separations. One side of the ball valve contains the inlet while the outlet is located on the other side. This design insures that no matter what position the valve is in, the fluid flows to one side exclusively. Butterfly valves are great for use with pumps and other mechanical devices that require quick and accurate control of the flow rate. However, their slow speed makes them less than ideal for high volume applications like fire extinguishers.
Diaphragm valves are great for regulating small amounts of gas and air entering or exiting a system. Their design minimizes the amount of backflow that could occur if the valve fails. If a diaphragm valve becomes stuck closed, it creates a vacuum within the chamber, sucking air into the piping system. Once the valve opens again, the air rushes back out. This problem is most likely to happen in large piping systems and is not really a concern in smaller settings.
A check valve is a type of valve that allows fluids to flow only in one direction. A typical example would be the body's natural urinary system where urine flows from the bladder into the urethra (the tube that carries urine out of the body). In a firefighting application, a check valve would allow water to travel out of the hose if the pressure inside the hose was greater than that outside the hose. If the check valve were not present, the fluid could flow back in. A ball valve works similarly to a check valve; however, instead of having two opposing openings, a ball valve has one single opening surrounded by a spherical piece of metal called a ball. When the ball is turned, the ball moves between the openings and prevents both from moving at once. Unlike a check valve, the ball valve doesn't require any pressure differential to function properly. Instead, it will open when the force applied exceeds its weight. Butterfly valves work much like ball valves except they have an additional, rotatable plate on top. When the plate is rotated counter-clockwise, the plate opens and allows gas to pass through the valve. When the plate is clockwise, the plate closes and blocks the passage of gases. Butterfly valves are somewhat uncommon in fire extinguishers because they tend to wear down over time.
Valves are commonly used in fire fighting situations where water is being utilized. There are different types of valves that are used and they each have their own specific purpose. A valve works like a gate that opens and closes to allow either liquid or gas to pass through. In firefighting, if a person were to use a regular water hose where the water was not pressurized, then the water would just run out and the firefighter could potentially struggle getting the water back onto the hose. However, if a person were using a high pressure spray system where the spray comes at extremely high pressures, then the water should go much farther than if they were just using a garden hose. When choosing a high pressure spray system, it’s important to make sure that you get the right equipment and that it fits your circumstances. For example, if you were a commercial business owner, then you may want to consider purchasing a larger size nozzle that is capable of delivering water in a wider area.
There are two specific types of valves in firefighting; check valves and ball valves. Check valves work similar to a door hinge because they open to allow flow only in one direction. Typically these valves are used to prevent water from flowing backwards. On the contrary, ball valves are closed and do not allow any passage. The valves are opened after the correct pressure is reached and then released once the water begins to flow freely again. Ball valves also provide higher flow rates than check valves.
Access all the previous parts of this full fire fighting series by clicking the links provided below:
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