Two types of solenoid valves: direct-acting and pilot-operated

Sep 27, 2025

Imagine a water faucet. Turning it on directly by hand requires some effort, but the response is immediate. Now, picture a massive sluice gate: we only need to gently turn a small valve, using the water's own power to open the giant gate. Similarly, direct-acting and pilot-operated solenoid valves are two common methods of controlling fluids in industrial manufacturing.

Direct-Acting Solenoid Valves

The direct-acting solenoid valve is unequivocally a simple, reliable, no-nonsense performer.The working principle of a direct-acting solenoid valve involves using electromagnetic force to directly drive the valve core. The solenoid coil generates a magnetic field, which overcomes the spring force, pulls the plunger up, and opens the valve. When power is off, the spring force pushes the plunger back, closing the valve.

Main Characteristics

Zero Pressure Differential Operation: Relies on electromagnetic force to overcome the plunger's spring force, enabling operation with zero pressure differential.

Fast Response Speed: A typical feature is its rapid response, resulting from the direct conversion of electrical energy into mechanical movement.

High Reliability: Another key characteristic is the absence of external driving components. With fewer moving parts, the probability of failure is lower.

Energy Efficiency and Environmental Friendliness: Unlike motorized valves that often require continuous power to maintain position, solenoid valves only consume electricity during the switching action (when fluid flow needs to be started or stopped), leading to lower power consumption and a more eco-friendly profile.

Application Scenarios

Suitable for small-diameter pipelines, as the required electromagnetic force limits size. The valve's compact structure is ideal for smaller lines.

Ideal for systems requiring rapid response due to the direct electrical actuation of the plunger.

Can operate in vacuum and low-pressure environments because valve opening relies solely on electromagnetic force; fluid pressure, which is negligible in these conditions, does not hinder operation.

More tolerant of fluids containing particulates compared to pilot-operated valves, as the absence of a small pilot orifice reduces the risk of clogging. The flow path is more direct.