What is a valve?

Nov. 25, 2019

Valves are control components in fluid delivery systems that have functions such as shut-off, regulation, diversion, backflow prevention, regulation, shunting or overflow relief. A valve is a device that allows a pipe or a medium (liquid, gas, powder) in a device to flow or stop and control its flow rate. Valves can be used to control the flow of various types of fluids such as air, water, steam, various corrosive media, mud, oil, liquid metals, and radioactive media.

Valves for fluid control, from the simplest globe valve to the most complex self-control systems, are available in a wide variety of sizes and sizes. The nominal diameter of the valve ranges from very small instrument valves up to 10m. Valves for industrial piping. According to the material, the valve is also divided into cast iron valve, cast steel valve, stainless steel valve (201, 304, 316, etc.), chrome molybdenum steel valve, chrome molybdenum vanadium steel valve, duplex steel valve, plastic valve, non-standard custom valve. The valve can be used to control various types of fluids such as water, steam, oil, gas, mud, various corrosive media, liquid metal and radioactive fluid. The working pressure of the valve can be from 0.0013MPa to 1000MPa. From ultra-low temperature of -269 ° C to high temperature of 1430 ° C.

Valve control can be used in a variety of transmission methods, such as manual, electric, hydraulic, pneumatic, turbo, electromagnetic, electromagnetic hydraulic, self-operated type control valve, gas-hydraulic, spur gear, bevel gear drive, etc.; can be under pressure, temperature Under the action of other forms of sensing signals, according to predetermined requirements, or simply open or close without relying on the sensing signal, the valve relies on a drive or an automatic mechanism to cause the opening and closing member to be lifted, slid, swung or swung. Movement, thereby changing the size of its flow path area to achieve its control function.

Globe Control Valve

Globe Control Valve

Daily valve maintenance

1. The valve should be stored in a dry and ventilated room, and both ends of the passage must be blocked.

2. Valves stored for a long time should be inspected regularly to remove dirt and apply anti-rust oil on the processing surface.

3. After installation, it should be checked regularly, mainly for inspection items:(1) Wear of the sealing surface.

(2) Trapezoidal thread wear of the stem and stem nut.

(3) Whether the filler is out of date or not, and if it is damaged, it should be replaced in time.

(4) After the valve is overhauled and assembled, the sealing performance test shall be carried out.

Regulating valve in operation, all valve parts should be complete and intact. The bolts on the flange and the bracket are indispensable, the thread should be intact and no looseness is allowed. The tightening nut on the hand wheel should be tightened if it is loose, so as not to wear the joint or lose the handwheel and nameplate. If the handwheel is lost, it is not allowed to replace it with a wrench. It should be timely. The packing gland is not allowed to be skewed or has no pre-tightening clearance. For valves in environments that are susceptible to contamination by rain, snow, dust, sand, etc., the valve stem should be fitted with a protective cover. The scale on the valve should be complete, accurate and clear. The seals, caps and pneumatic accessories of the valve should be completed. The insulation jacket should be free from dents and cracks. It is not allowed to hit, stand or support heavy objects on a running valve; especially non-metallic valves and cast iron valves are prohibited.