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Humphrey Valves: Pilot, Proportional, and Latching Types

October 16, 2014 | written by twg

What are Pilot Valves?

Pilot valves are small, 3-way, subbase mount, direct-acting solenoid valves. They use low power and can thus be operated by smaller power supplies, controllers, or even batteries. They have a pressure rating and flow capacity sufficient to shift, or “pilot” larger process or work valves, such as those controlling large bore cylinders, fluids, or gases.

They are a cost effective, pneumatic “interface” between PLC controllers and fluid power and fluid handling work valves. They also work well in low flow pneumatic applications, such small bore single acting cylinders. Their mounting configuration makes each valve suitable for both multiple valve manifolds, single valve subbase, or custom configurations.

What are Proportional Valves?
Proportional valves are basically electronic flow controllers. When you vary the input current to the solenoid – the output flow of the valve will vary accordingly. As the input current is increased, so does the flow through the valve. Typical applications are dynamically dispensing controlled amounts of air or gas, controlling downstream pressures, or accelerating/decelerating air cylinders. Humphrey proportional valves are two-port, normally closed, direct acting, spring return type flow controllers.

What are Latching Valves?
Also known as bi-stable valves, latching valves use a permanent magnet within the solenoid. When current flows through the solenoid in one direction the armature moves into the permanent magnetic field, shifting the valve stem to one flow state. The force of the permanent magnet is sufficient enough such that the armature “latches” after current is removed. When current flow to the solenoid is applied in the opposite direction, the force of permanent magnetic field is effectively “neutralized”. The return spring then can shift the valve to another flow state. It takes only a 50 millisecond minimum pulse of electrical current to the solenoid will shift and secure the armature into the desired state. This saves energy normally applied to hold a valve in place.

Diffley-Wright is the exclusive distributor in Florida for Humphrey valves and other products.