Sinclair Collins® High Pressure Valves - Norman Equipment Co.

HP Series High Pressure 3 Way2 Pressure Control Valve: How it WorksSinclair Collins® 3-Way Two-PressureHydraulic Control Valves are widely usedin press operations or in other similarapplications where low and highoperating pressures are employed.Diaphragm-operated, they may beactuated by manually, electrically ormechanically operated air valves. Theyare designed to control two pressuresystems where the low pressures rangefrom 50 to 2000 psi and high pressuresup to 3500 psi.The "low pressure" range of aTwo-Pressure Valve depends upon theHigh Pressure Automatic Inlet Valveordered for the assembly. High PressureAutomatic Inlet Valves are available for"low pressure" ranges of 50 to 150, 150to 400, and 400 to 2000 psi. Anadjustment screw on the High PressureAutomatic Inlet Valve provides accurateadjustment of the low pressure point(within the operating range) atwhich the high pressure "kicks in".In most press operations, low-pressureis used to close the ram the majority ofthe stroke. As the ram closes and meetsincreasing resistance, the resultinglow-pressure build-up lifts the plungerof the High Pressure Automatic InletValve admitting high pressure fluid intothe ram to close/clamp. The "kick-in"stage of the process can also bemanually controlled by substituting astandard 2-way normally closed valve inplace of the High Pressure AutomaticInlet Valve. Our model HP204-3001, a3/4" 4000 psi normally closed valve, isrecommended. This type of installationmight be used where the first phase of acure is run under low-pressure and thecure completed under high pressure.By the addition of a reverse-acting valvein the low pressure inlet line during theclosing stroke, the press ram can beheld in any position desired; or the ramcan be allowed to close the mold to thepoint where the ram pressure willincrease a few psi. This slight backpressure is used to close an inlet valvewhich bypasses the inlet pressurethrough a smaller orifice so the ram willclose slowly before the high pressureautomatically "kicks in".Pull-backs can be supplied through a3-way valve and the pressure removedfrom the pull-back cylinders while theram is stroking and also for curing time;at end of cure, the pressure can berestored to pull-back.8