Considerations for valve type selection Common elements of imported valve type selection

Considerations for valve type selection Common elements of imported valve type selection

I. Electric regulating valve
Valve body material (or pipeline material), nominal pressure, working pressure (valve front pressure and closing pressure difference), which determines whether to use a single seat or sleeve valve, valve diameter (DN), medium and temperature, electric actuator without requirements, voltage explosion-proof. Control signal (generally 4-20mA), traffic characteristics are not required, the customer has no special requirements. Electric control valve straight stroke and Angle stroke (ball valve, butterfly valve) two. They differ in that linear strokes are highly accurate, fast, and can be adjusted through a variety of frequencies. But the Angle motion accuracy is poor, the motion speed is slow and so on. Specific can refer to customer requirements.
Electric ball valve and butterfly valve
Body material, working pressure, connection mode (ball valve less than DN 50* threaded connection, greater than DN 50 flange connection), valve diameter (DN), butterfly valve diameter can only ** small DN 40. At the same time, butterfly valve has two connection modes: clip type and flange type. The TYPE AND temperature of the medium (temperature determines the use of sealing materials, the type of medium is used to determine whether the valve is sealed with hard alloy or soft), the valve is open or closed (switch type can only be opened and closed in position, adjustment type can open the valve to any opening, flow can be adjusted).
Three. Pneumatic control valve
Body material (or pipe material), nominal pressure, working pressure (pre valve pressure and close pressure difference, which determines whether to use a single seat or sleeve valve), valve diameter (DN), medium type and temperature, whether explosion-proof. Whether or not flow characteristics are required, air open or gas closed. Positioner control signal (usually 4-20mA input, if output feedback signal is needed, then calculate the price, the price of this positioner is more expensive than the price of * input), how many kilograms of air supply pressure. The ball valve and butterfly valve can also be adjusted after the positioner is installed, which is relatively less costly than the direct stroke but less accurate. Suitable for *** adjustment.
Pneumatic ball valve and butterfly valve
Pneumatic switch valve standard accessories: solenoid valve, limit switch, air source processing three parts.
Pneumatic control valve standard accessories: valve positioner gas source processing two parts
Valve material, valve working pressure, valve medium and temperature, if it is a switch type, you need to ask the voltage of the solenoid valve (generally AC220V and DC24V optional, the same price), pneumatic ball valve and butterfly cylinder is divided into two kinds (one is single, the valve open or close, the valve closed or open automatically closed; The other is double action, valve ventilated or closed, valve re-ventilated or open.) Butterfly valve needs to ask clamping type, flange type, welding type, etc. Similarly, the mediumtemperature type determines the body material and seal material. (BALL VALVE IS GENERALLY sealed WITH TEFLON, the use temperature is below 130 degrees, can be used for any corrosion situation, 130 DEGREES ABOVE CAN be used FOR enhanced TEflON, 220 degrees above can only be hard sealed, BUTTERFLY valve CAST IRON MATERIAL IS GENERALLY sealed with rubber, cast steel and stainless STEEL IS generally sealed WITH TEflON (PTFE). Hard seal butterfly valves are usually used as elastic hard seals and multistage hard seals. Relatively speaking, the use of multiple levels is more. Its performance is also better than the elastic seal.
Five. Solenoid valve
Solenoid valve on the medium requirements are very strict, so it is necessary to ask the medium, model and temperature. If there are impurities and particles, suspended matter and viscosity (glue sample), solenoid valve can not be used, you can choose another valve. How much voltage there is (the price of AC220V or DC24V may vary), often on or off (usually on is when the valve leaves the factory, the power is turned off, often off is the opposite). What is the working pressure of the valve (this is important), the connection mode (usually with flanges and threads).
Import valve selection of common elements
There are many factors to consider in the selection of imported valves, but according to the direction of the valve fluid, the flow control of the valve, and the characteristics of the medium to select, is often an important factor to consider; Combined with German Lit-LIT brand valve, to analyze the selection of factors
Valves for cutting off and opening media
The flow channel is a straight-through valve, commonly used import butterfly valve, import gate valve, import ball valve, etc., the flow resistance is small, usually selected as a cut-off and open medium with the valve. And downward closed valve (import globe valve, plunger valve) because of its tortuous flow path, flow resistance than other valves, so less choose. In allowing a higher flow resistance, such as the transmission medium for the occasion of gas can be selected down closed valve. In the selection of imported butterfly valve, when the transmission medium has more impurities, such as raw water or sewage transmission, horizontal butterfly valve should be selected, because the valve shaft is horizontal, the bottom of the flow passage is not easy to accumulate debris and scale, to protect the valve plate sealing ring; Or choose German LITLIT brand imported hard seal butterfly valve, can ensure sealing and wear resistance, service life. Gate valves should also be selected as far as possible without grooves at the bottom of the valve passage to avoid leakage caused by debris accumulation in the groove.
Two, control the flow of the valve
Usually choose easy to adjust the flow of the valve as a control flow, also known as the import regulator. Downward CLOSING valves (such AS GLOBE valves) ARE SUITABLE FOR THIS PURPOSE BECAUSE THE SEAT size IS PROPORTIONAL TO THE STROKE OF THE SHUTOFF. Rotary VALVES (rotary PLUG, butterfly, ball valves) and FLEXure BODY VALVES (PINCH, DIAPHRAGM) ARE ALSO AVAILABLE FOR THROTTLING CONTROL, but USUALLY ONLY in a limited range of valve DIAMEters. Gate VALVE IS A disc shaped gate to the circular seat port to do transverse motion, it only in close to the closed position, can better control the flow, so usually not used for flow control.
Three, reversing shunt valve
The valve may have three or more channels, depending on the need for reversing and diverting. Plug and ball valves are more suitable for this purpose, and therefore, most valves used for reversing and diverting are selected as one of these valves. However, IN SOME CASES, other TYPES OF VALVES MAY ALSO BE USED AS commutATION diverTERS, PROVIDED THAT TWO or MORE VALVES ARE properly connected to EACH other. For example, take the German Litt LIT valve as an example, the main inlet three-way ball valve, inlet three-way plug valve, three-way ball valve is divided into T and L type.
4. Valves for medium with suspended particles
When there are suspended particles in the medium, it is suitable to use its closing parts along the sealing surface of the sliding valve with wiping action. If the shutoff motion to and from the seat is vertical, particles may be trapped. Therefore, THE VALVE IS ONLY SUITABLE FOR USE IN GENERALLY CLEAN MEDIA UNLESS THE SEALING surface MATERIAL ALLOWS FOR THE INCORPORATION OF PARTICLES. Ball valves and plug valves wipe the sealing surface during opening and closing, so they are suitable for use in media with suspended particles. The selection of LITT LIT is recommended, using imported knife gate valve, imported V ball valve.