When your application calls for high-precision parts, you need a stamping partner that can hold the tightest quality standards. Balford is an ISO 9001:2015-registered company that has been manufacturing precision metal components for customers worldwide since 1975. Today we produce more than one million parts every week, including components for the most technically demanding applications.

When your industry requires high-caliber precision parts, you need a stamping company that meets the most stringent quality standards. balford, an ISO 9001:2015-registered company, has been manufacturing precision tools for companies worldwide since 1975. Today, we produce over 1 million highly detailed parts every week for even the most technologically advanced applications.

A solenoid valve works on the electromagnetic force generated by a coil: switching the coil current on and off controls the mechanical movement of the valve. Inside the valve is a sealed cavity with several ports, and each port connects to a different hydraulic line. A spool sits in the cavity, with an electromagnet at each end. When the electromagnet on one side is energized, it pulls the spool toward that side, opening or closing the corresponding drain ports. The inlet port remains open, so hydraulic oil is directed into the appropriate outlet line, where line pressure pushes the cylinder piston and rod to drive the mechanical load. In short, energizing and de-energizing the coil is what controls the motion.

Operating Principles and Characteristics

Direct-acting solenoid valve: With no power, the valve stays closed; when power is applied, the coil's electromagnetic force lifts the valve open. This type suits vacuum, negative-pressure, and zero-pressure applications, but port sizes are generally small.

Step-by-step direct-acting solenoid valve: This design combines direct-acting and pilot-operated principles. With no pressure differential it opens directly when powered; with a differential present it uses both coil force and line pressure to open. It closes when power is removed. It works across zero differential, vacuum, and high-pressure conditions, but draws more power and must be installed horizontally.

Pilot-operated solenoid valve: Energizing the coil opens the pilot port, and the pressure differential then pushes the main valve open. De-energizing closes the pilot port and the valve returns to closed. This design is compact, draws little power, and handles high fluid pressures. It can be mounted in any orientation, but a minimum pressure differential is required.

Specifying a solenoid valve also means reviewing the fluid parameters (medium, temperature class, fluid state, viscosity), pressure parameters (nominal pressure, working pressure), electrical requirements (voltage rating), duty cycle, and environmental features such as explosion-proof, check, manual override, waterproof, spray-rated, or immersion-rated protection. These factors together determine which valve is the right fit.