3/2 Coaxial Solenoid Valve

Basic Principle

How 3/2 coaxial solenoid valves work.

Valve working basics.

3/2 normally closed coaxial solenoid valve Pressure: Flow P to A or P to R Maximum Flow A to P or R to P 16 Bar	Fail safe Closed -  Flow A to R, P to A Closed	Energised Open, Flow P to A, A to R closed
3/2 normally open coaxial solenoid valve Pressure: Flow P to A or P to R Maximum Flow A to P or R to P 16 Bar	Fail safe Open -  Flow P to A, P to R Closed	Energised Closed, Flow P to R, P to A closed

Technical Data Sheets

Click on the links below for the full PDF technical data sheets.

Model	Max Pressure (Bar)	Port Sizes	Port Type	Orifice Sizes (mm)	Body Material	Seal Options
370	40	1/4, 3/8, 1/2, 3/4, 1, 11/4, 11/2, 2"	BSP, NPT Thread or flange	10,15,20,25,32,40,50	Brass, AISI303 Stainless Steel or AISI316 Stainless Steel	FKM, PTFE
371	64	1/4, 3/8, 1/2, 3/4, 1, 11/4, 11/2"	BSP, NPT Thread or flange	10,15,20,25,32	Brass, AISI303 Stainless Steel or AISI316 Stainless Steel	FKM, PTFE
390 ATEX	20	1/4, 3/8, 1/2, 3/4"	BSP, NPT Thread or flange	10,15	Brass, AISI303 Stainless Steel or AISI316 Stainless Steel	FKM, NBR, EPDM

3/2 Coaxial solenoid valve orifice sizes and flow rates.

3/2 way Coaxial solenoid actuated valves are available with a wide range of orifice or tube internal diameter sizes offering a variety of flow rates to suit the application at hand. As the stainless steel tube controls the media flow the diameter is the major factor in determining the flow coefficient of the valve in that the bigger the orifice (tube diameter) the higher the flow coefficient but also increases the size of the coaxial valve body and cost. Coaxial valves are offered with a range of orifice sizes for each port connection size for example a 3/4" BSP valve could be supplied with a 10mm, 15mm or 20mm tube offering different flow rates accordingly, the 10mm of course being smaller valve and less expensive than the 15mm or 20mm versions. There are logical limitations for orifice and port size combination, for example choosing a 1/2" port but requiring a 25mm orifice would be pointless as the flow restriction as the port entrance prevents any increase in flow beyond the 20mm tube flow limit.

3/2 Coax solenoid valve control voltages.

All coaxial solenoid controlled valves work on the principle of an electro magnet energised by a control voltage to move the internal tube into the open of closed position. The control voltage can be chosen according to each application but all coaxial valves operate on a DC (direct current) only as their design dictates that they are unable to handle AC 50/60Hz alternating current. To over come this problem with AC voltage supply the coax solenoid is equipped with a full bridge rectified electrical DIN43650A (Form A 28mm square) connector which will convert the AC supply current and output a rectified DC current to the valve. This simple solution, thanks to some clever circuitry within the connector allows for applications where 24vAC, 110vAC or 230vAC 50/60Hz is the preferred voltage and are easily converted to DC. Engineers must be aware that any coaxial valve used on an AC supply MUST HAVE this special rectified connector installed, otherwise the coaxial valve will hum or buzz loudly for a while before burning out the coil. The most commonly used coaxial valve voltages tend to be 24vDC and 230vAC (rectified), however options for 12vDC, 24vAC (rectified to 24vDC), 48vDC, 48vAC (rectified) and 110vAC (rectified to 110vDC) are available typically with a small additional cost.