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salahzantout
09-09-2013, 05:26 PM
Hello engineers

Would like to know about the delta P across a solenoid valve in order to select it from the catalogue... ofcourse you all know we need the capacity and delta P.

I only know the capacity but need to know the delta P... any idea about that ?

Thanks in advance

chemi-cool
09-09-2013, 06:44 PM
You will find it in any catalogue of any manufacturer as long as it is not Chinese.

salahzantout
10-09-2013, 08:46 AM
ive checked it in danfoss... its not there... please if you could link me to one it would be great

monkey spanners
10-09-2013, 10:15 AM
Why do you need the delta P across the solenoid? If the kW rating is ok i would expect the dp to be ok too, but am willing to learn otherwise.

marc5180
10-09-2013, 12:16 PM
Why do you need the delta P across the solenoid? If the kW rating is ok i would expect the dp to be ok too, but am willing to learn otherwise.

Is it do do with the opening of the valve.
I know that most solonoids that I work with require a low pressure differential where as some valves work different.

marc5180
10-09-2013, 12:21 PM
Solenoid Valve Selection
The selection of a solenoid valve for a particular control application requires the following information:
1. Fluid to be controlled.
2. Capacity required.
3. Maximum operating pressure
differential (MOPD).
4. Electrical characteristics.
5. Safe working pressure required
(SWP).
The capacities of solenoid valves for normal liquid or suction gas refrigerant service are given in tons of refrigeration at some nominal pressure drop and standard conditions. Manufacturers’
Solenoid Valves catalogs provide extended tables to cover nearly all operating conditions for common refrigerants. Follow the manufacturer’s sizing recommendations. Do not select a valve based on line size. Pilot operated valves require a minimum pressure drop to operate, and selecting an oversized valve will result in the valve failing to open. Undersized valves result in excessive pressure drops.
The solenoid valve selected must have a MOPD rating equal to or in excess of the maximum possible differential against which the valve must open. The MOPD takes into consideration both the inlet and outlet valve pressures. If a valve has a 500 psi inlet pressure and a 250 outlet pressure, and a MOPD rating of 300 psi, it will operate, since the difference (500– 250 = 250) is less than the 300 MOPD rating. If the pressure difference is larger than the MOPD rating, the valve will not open.

salahzantout
10-09-2013, 08:59 PM
thanks but still we did not know of how to get the pressure on outlet... usually the inlet is known cause it would be holding condenser pressure or so

but thanks anyway
appreciated

marc5180
10-09-2013, 09:26 PM
In what application would it be being used? Also is it a normal direct acting solonoid or a pilot operated valve?

marc5180
10-09-2013, 09:34 PM
Direct operated solenoid valves
Direct operated solenoid valves function to directly open or close the main valve orifice, which is the only flow path in the valve. Direct operated valves are used in systems requiring low flow capacities or in applications with low pressure differential across the valve orifice. The sealing surface that opens and closes the main valve orifice is connected to the solenoid plunger. The valve operates from zero pressure differential to maximum rated pressure differential (MOPD) regardless of line pressure. Pressure drop across the valve is not required to hold the valve open.

marc5180
10-09-2013, 09:35 PM
Pilot operated solenoid valves
Pilot operated valves are the most widely used solenoid valves. Pilot operated valves utilize system line pressure to open and close the main orifice in the valve body. In a piston-style valve, the main orifice is held closed with a piston seal pressed against the main orifice by the combined fluid pressure and spring pressure. In a normally closed valve, the piston is shifted or opened when the pilot operator is energized. This allows fluid behind the piston to evacuate through the valve outlet. At this point, the system line pressure moves the piston, opening the main orifice of the valve allowing high capacity flow through the valve. When energizing the coil of a normally open valve, fluid pressure builds up behind the piston, forcing the piston to seal the main orifice of the valve.