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Working principle: The valve body contains a gate-type closing member. The movement direction of the gate is perpendicular to the flow direction. Because it can block water just like a sluice gate, it’s called a gate valve.
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Scope of application: Fire pump discharge pipe and suction pipe; discharge pipe and suction pipe of the pressure-stabilizing pump; fire water supply network
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Additional note: The stem of the rising stem gate valve is exposed, making the degree of opening and closing fairly intuitive; however, the stem itself is also subject to corrosion.
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Working principle : Rising stem gate valve
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Scope of application: Fire pump suction pipe; fire water supply network
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Additional note: Compared to rising stem gate valves, hidden stem gate valves have stems that are not exposed, and their degree of opening and closing is not immediately obvious, making them suitable for concealed installations.
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Working principle: The closing member (disc or butterfly plate) is a circular disc that rotates around the valve stem to achieve opening and closing. Close A type of valve.
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Scope of application: Fire pump discharge pipe and suction pipe; indoor overhead pipelines.
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Additional notes The applicability of butterfly valves is similar to that of gate valves, and some provisions require them to have a self-locking function.
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Work Principle: When gas leaks into the system, it flows upward through the piping and eventually accumulates at the highest point of the system. Air vents are typically installed at these high points. As gas enters the vent chamber and accumulates in the upper part of the vent, the pressure inside the vent rises. Once the gas pressure exceeds the system pressure, the gas causes the water level inside the chamber to drop, prompting the float to descend along with the water level and open the vent outlet. After the gas is completely exhausted, the water level rises, causing the float to rise as well and close the vent outlet.
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Scope of application: Automatic sprinkler system; dry fire hydrant; dry fire riser.
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Additional note: Dry systems, pre-action systems, and dry fire hydrant systems are equipped with quick exhaust valves, and are also fitted with corresponding electric valves.
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Working principle: An automatic drip valve is installed on the valve body on the system side of the rainwater alarm valve system (for dry-type alarm valves, the alarm piping is diverted via a tee fitting). Under normal conditions, any water leaking from the supply side into the system side is automatically drained through the drip ball valve. During fire suppression, the drip ball valve automatically closes.
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Scope of application: Dry-pipe, pre-action, and deluge automatic sprinkler fire suppression systems.
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Additional note: Similar to a vent valve, it is characterized by low-pressure opening for drainage and automatic closure under high pressure.
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Low-leakage, high-sealing valve
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Working principle ： A valve installed in the pipeline to prevent the system from malfunctioning due to the accumulation of leakage from the driving gas.
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Scope of application: Gas fire suppression system.
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Add a supplement. Bright: Installed on the system’s starting line, it remains open under normal conditions and closes only when the inlet pressure reaches the set pressure. Its primary function is to vent the gas that has accumulated in the starting line due to air source leaks.
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II. Control valve types: Mainly used to regulate the pressure, flow rate, and other parameters of the medium.
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Work Principle: The pressure relief valve works by... Adjust Reduce the inlet pressure to a desired level. Export Pressure, relying on the energy of the medium itself, automatically maintains a stable outlet pressure. Valve The proportion formula utilizes Valve body The pressure difference created by the differing cross-sectional areas at both ends of the internal piston alters the pressure downstream of the valve, achieving the purpose of pressure reduction.
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Scope of application: Excessive pressure at fire hydrant outlets; pressure-reducing valves for zoned water supply; series-connected pressure reduction—first stage.
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Additional note: It should be installed vertically.
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Working principle: Adopt control Valve body The degree of opening of the valve’s closing member is adjusted to regulate the flow rate of the medium, thereby reducing the medium’s pressure. At the same time, leveraging the effect of the downstream pressure, the opening degree of the closing member is further adjusted to keep the downstream pressure within a specified, appropriate range. 。
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Applicable scope Encircle: When the pressure at the fire hydrant outlet exceeds the specified limit; or when the pressure reduction valve divides the water supply into zones and the pressure exceeds 1.20 MPa; in the case of series-connected pressure-reducing valves, the pressure difference between the upstream and downstream sides of the second-stage valve should preferably be no more than 0.40 MPa.
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Additional note: Install horizontally.
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worker Working principle: A throttling valve is a valve that controls fluid flow by altering the throttling cross-section or the length of the throttling passage.
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Scope of application: Fire hydrant and alarm valve assembly.
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Additional notes : Used to regulate flow pressure, Just understand it. 。
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Three, Check valve type: Used to prevent backflow of the medium.
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Working principle: A valve in which the closing member is a circular disc that relies on its own weight and the pressure of the medium to actuate and prevent backflow of the medium.
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Applicable Scope: The locations of the fire pump discharge pipe, the high-level fire water tank discharge pipe, the pressure stabilization pump discharge pipe, and the pump connection.
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Additional note: It includes both silencer check valves and water-hammer elimination check valves. It... We have implemented several measures inside the valve body to reduce the noise caused by the valve disc impacting during valve closure, as well as measures to eliminate water hammer.
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Working principle: A backflow preventer is a valve assembly consisting of two separate check valves and a safety relief valve.
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Scope of application: The discharge pipe of fire pumps drawing water from the municipal water supply network; the discharge pipe of series-connected pumps for zoned water supply; the water supply inlet pipe for outdoor fire hydrants; and the inlet pipe when firewater is supplied from the combined production and domestic water supply network.
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Additional note: It can be regarded as an enhanced check valve, with the primary function of preventing backflow of water. It can replace a check valve, but the reverse is not true.
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Working principle: One type of check valve, which is divided into liquid flow and gas flow.
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Scope of application: Suitable for gas fire suppression systems.
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Additional note: It functions the same as a check valve, ensuring unidirectional flow of the medium.
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Four, Safety valve category: Used for overpressure safety protection.
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Working principle: The safety valve is normally closed under the action of an external force on its closing member; when the equipment or... Pipeline inside Medium A special valve that prevents the pressure of the medium inside pipes or equipment from exceeding the specified value by discharging the medium to the outside of the system when the pressure rises above the specified limit.
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Scope of application: After the zone water supply pressure-reducing valve; fire pump connection; high-pressure fire pump discharge pipe; pressure storage tanks in gas extinguishing systems, dry powder extinguishing systems, and foam fire suppression systems.
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Additional note: Safety valve Location and Requirements for Setup It is the focus of the exam.
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Working principle: A type of safety valve.
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Scope of application: It is commonly used in gas fire suppression systems and automatic sprinkler systems.
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Additional note: Focus primarily on memorizing safety valves; it’s sufficient to have a basic understanding of relief valves.
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