12 Kinds of Common Fire Valves

A summary of valve knowledge
1. Gate valves
Working principles: there are gate opening and closing parts inside the valve body. The movement direction of the gate is perpendicular to the direction of the fluid. Because water can be blocked like the water gate, it is named a gate valve.
Scope of applications: gate valves are used for water outlet pipes and suction pipes of fire pumps, water outlet pipes and suction pipes of stabilized pressure pumps and fire water supply pipelines.
Supplementary notes: the screw rod of rising stem gate valves is exposed. The opening and closing degree is relatively intuitive, but the screw rod is also corroded.

Concealed poles
Scope of application: they are used for fire pump suction pipes and fire water supply pipelines.
Supplementary notes: compared with the rising stem gate valves, the rotating rod of the rising stem gate valve is not exposed. And the opening and closing degree is not intuitive, which is suitable for concealed works.
 

2. Butterfly valves
Working principles: the closing piece (discs or butterfly plates) is a kind of valve which is opened and closed by rotating around the valve axis.
Scope of applications: they are used for fire pump outlet pipes, suction pipes and indoor overhead pipes.
Supplementary notes: the applicability of butterfly valves is similar to that of gate valves, and some articles require self-locking functions.

3. Exhaust valves
Working principles: when there is gas overflow in the system, the gas will go up along the pipeline and finally gather at the highest point of the system, while the exhaust valve is generally installed at the highest point of the system. When the gas enters the exhaust valve chamber and gathers at the upper part of the exhaust valve, the pressure will rise with the increase of the gas in the valve. When the gas pressure is greater than the system pressure, the water surface in the chamber will fall, and the pontoon will rise. When the water level drops, open the vent; when the gas is exhausted, the water level rises. When the pontoon also rises, close the vent.
Scope of applications: they are used for automatic sprinkler systems, dry fire hydrant and dry fire riser.
Supplementary notes: dry-type systems, pre action systems and dry-type hydrant systems are equipped with quick exhaust valves and corresponding electric valve.

4. Automatic drip valves
Working principles: an automatic drip valve is installed on valve body at the system side of the deluge alarm valve (a dry-type alarm valve is installed on alarm pipeline and is divided by three-way pipes and alarm pipelines). The water leakage from water supply sides to the system side is automatically discharged by drip ball valves at ordinary times, and a drip ball valve is automatically closed when extinguishing the fire.
Scope of applications: they are used for dry type, pre action and deluge automatic sprinkler systems.
Supplementary notes: it is similar to the exhaust valve and characterized by opening drainage under low pressure and being automatically closed under high pressure.

5. Little discharge and high seal valves
Working principles: valve sets in the pipeline prevent systems from misoperation due to the accumulation of driving gas leakage.
Scope of applications: they are used for gas fire extinguishing systems.
Supplementary notes: it is installed on the start-up pipeline of the system, which is in open state under normal conditions. It can only be closed when inlet pressure reaches set pressure. Its main function is to eliminate gas accumulated in the start-up pipeline due to the leakage of air source.
 

B). Regulating valves: they are mainly used to regulate the pressure and flow of the medium.
1. Reducing valves
Working principles: the pressure reducing valve is a valve that reduces the inlet pressure to a certain required outlet pressure through regulation, and makes the outlet pressure automatically keep stable depending on the energy of the medium itself. The proportional type is to use the pressure difference caused by the different cross-sectional areas of the two ends of the piston inside the valve body to change the pressure behind the valve to achieve the purpose of reducing pressure.
Scope of applications: they are used for hydrant port overpressure, pressure reducing valve zone water supply and series pressure reducing first stage.
Supplementary notes: they should be installed vertically.

Pilot-operated types
Working principles: they adopt opening of the gate in valve body to regulate the flow of medium, reduce pressure of the medium, and adjust the opening of the gate with the help of pressure behind the valve to keep the pressure behind the valve within a certain range of applications.
Scope of applications: they are used for hydrant port overpressure, pressure reducing valve zone water supply more than 1.20MPa and series pressure reducing level II, and the pressure difference before and after the valve should be ≤ 0.40MPa.
Supplementary notes: they should be installed horizontally.

2. Throttle valves
Working principles: a throttle valve is a valve that controls the flow of fluid by changing the throttle section or length.
Scope of applications: they are used for fire hydrant and alarm valve groups.
Supplementary notes: they are used to adjust the flow pressure.
 

 

C). Check valve types: they are used to prevent backflow of medium.
1. Check valves
Working principles: the opening and closing piece is a kind of valve with circular discs and its action is generated by its weights and medium pressure to block the backflow of medium.
Scope of applications: they are used for water outlet pipes of fire pumps, water outlet pipes of high-level fire water tanks, water outlet pipes of stabilized pressure pumps, water pump adapters, etc.
Supplementary notes: they include silencing check valves and water hammer elimination check valves. They are measured to reduce the sound of valve flap impacts when the valve is closed.

2. Backflow preventer
Working principles: the backflow preventer is a valve device composed of two separate check valves and a safety drain valve.
Scope of applications: it is supplied to water outlet pipes of fire pump pumped from municipal pipelines, water outlet pipes of water pumps in series for district water supply, water supply pipes of outdoor fire hydrant.
Supplementary notes: it can be regarded as a reinforced check valve, which is mainly used to prevent water from flowing back. It can replace the check valve.

3. One-way valves
Working principles: the one-way valve is one of check valves.
Scope of applications: the one-way valve is applicable to gas fire extinguishing systems.
Supplementary note: the one-way valve has the same function as the check valve to ensure one-way flow of medium.

D). Safety valves used for overpressure safety protection
1. Safety valves
Working principles: a safety valve is a special valve whose opening and closing parts are normally closed under the action of external force. When the medium pressure in the equipment or pipeline increases beyond the specified value, the medium pressure in the pipeline or equipment is prevented from exceeding the specified value by discharging the medium outside the system.
Scope of applications: they are applied to partitioned water supply pressure relief valves, water pump adapters, high pressure pump outlet pipes, gas fire extinguishing systems, dry powder fire extinguishing systems and foam fire control system pressure tanks.
Supplementary notes: the location and requirements for safety valve setting are the key points. 

2. Pressure relief valves
Working principles: a pressure relief valve is one of safety valves.
Scope of applications: a pressure relief valve is mainly used in gas fire extinguishing systems and automatic sprinkler systems.