on by spring 24 a gasket 23 is integral to the plunger the spring and plunger are contained in housing 25 when housing 25 is assembled to the manifold block 2 the spring 24 causes the plunger to press against and seal port 20 electric coil 26 mounts on housing 25 and is retained by a clip 27 wires for power are connected to terminals 28 alternatively flying leads which are integral to the coil could be employed thus eliminating the need for terminals when power is applied to the coil 26 plunger 22 is lifted due to the magnetic field this opens port 20 so fluid can pass through inlet port 19 to outlet port 21 fig3 shows a cut away section iii iii of fig4 of a check valve on the secondary block 2 shown disassembled the secondary manifold block 2 is designed so as to direct fluid from an inlet port 29 to port 30 and finally to the outlet port 31 a plunger 32 is acted on by spring 34 a gasket 33 is integral to the plunger the spring and plunger are contained in housing 35 spring 34 is designed so that a specified pressure at port 30 will cause plunger 32 to rise and therefore open port 30 so fluid can pass from inlet port 29 to outlet port 31 fluid introduced at port 31 will not flow to port 29 since plunger 32 will be held against port 30 thereby blocking flow referring to fig1 electrical connections to electrically operated flow control devices such as solenoid valves pressure switches and pressure transducers on the secondary manifold block 2 are made using wiring harness 36 individual wires from the various devices are.