How to Choose the Best Pressure Switch for Hydraulic Applications

Hydraulic applications require pressure switches that can withstand pressure spikes, vibration, temperature extremes, and harsh operating environments while maintaining accurate, repeatable switching performance. Unlike pneumatic systems, hydraulic systems use incompressible fluid to generate force.

Sudden changes in fluid velocity can place significant stress on pressure instruments. Mobile and industrial hydraulic equipment also expose switches to moisture, dirt, and wide temperature swings that can shorten instrument life if the wrong switch is selected.

Choosing the right pressure switch helps improve hydraulic system reliability, protect equipment, and maintain safe operation. Read this article to learn common challenges of hydraulic applications and important features to look for when selecting a pressure switch.

What are the primary challenges for pressure switches used in hydraulic systems? 

Hydraulic systems operate in some of the harshest industrial and OEM environments. Construction equipment, agricultural machinery, hydraulic presses, and hydraulic power units often experience constant vibration, pressure pulsation, and sudden shock loads during operation. 

These conditions can quickly damage poorly designed pressure switches or cause nuisance switching events that reduce system reliability. Here's a quick review to explain:

1. Pressure spikes and pulsation

Pressure spikes, also called hydraulic impulses, occur when fluid flow changes rapidly within the system. Similar to a water hammer effect, these pressure waves can develop in microseconds and temporarily rise several times above normal operating pressure.

In many hydraulic systems, pressure spikes can reach four to five times the normal working pressure. Over time, repeated spikes and pulsations can damage internal switch components, reduce setpoint accuracy, and shorten instrument life.

What feature should a pressure switch have to protect against spikes and pulsation?

To protect your pressure switch from the effects of pressure spikes and pulsation, be sure the instrument has the following:

• Sufficient overpressure protection to withstand demanding hydraulic operating conditions. One example is the Ashcroft® H-Series pressure switch, which is part of the Ashcroft® B-Series offering. The H-Series is specifically designed for hydraulic applications and offers proof pressures up to 12,000 psi, depending on the range.  

• Accurate and repeatable setpoints that can activate alarms, shut down pumps or protect hydraulic equipment from unsafe operating conditions. 

2. Shock and vibration

Hydraulic systems used in mobile equipment are regularly exposed to vibration from engines, pumps, actuators and uneven terrain. These vibrations create harmonic pressure waves and mechanical stress that can affect pressure switch performance.

Poorly designed switches may false trip, drift out of calibration, or wear prematurely in these environments.

What feature should a pressure switch have to protect against shock and vibration?

When excessive shock and vibration are a concern, you want to select a switch that is designed with rugged construction features that improve durability in demanding environments.

Most hydraulic pressure switches use a piston design rather than a diaphragm design to actuate the switch. This matters because piston-style actuators are generally better suited for high-pressure hydraulic systems and can better withstand the harsh conditions commonly found in these applications.

Other important construction features may include:

• Durable wetted materials

• Corrosion-resistant components

• Watertight enclosure options

• Hermetically sealed switch elements

The Ashcroft® F-Series, for instance, has a rugged piston-actuator design for setpoints between 1,000 and 4,000 psi. It features hermetically sealed switch options. 

3. Environmental exposure

Many hydraulic systems operate outdoors or in harsh industrial environments where pressure switches are exposed to rain, mud, dust, washdown conditions, and extreme temperatures.

What feature should a pressure switch have to protect against environmental exposure?

Two of the most common environmental protection standards used for pressure switches are Ingress Protection (IP) ratings and National Electrical Manufacturers Association (NEMA) enclosure ratings. 

• IP ratings classify how well an enclosure protects against solid particles and liquid ingress. In hydraulic applications, ratings such as IP66 and IP67 are commonly used for protection against dust, heavy spray, and temporary water immersion.

• NEMA ratings define enclosure protection for industrial environments. Hydraulic pressure switches commonly use ratings such as NEMA 4, 4X, and 6 for protection against water, corrosion, oil, and washdown conditions.

The Ashcroft® H-Series Pressure Switch features watertight NEMA 4X enclosure protection with IP66 ratings. Another option is the A-Series watertight pressure switch, offering NEMA 6 and IP 67. It is designed for outdoor and washdown environments where additional environmental protection is required.

Which pressure switches work best for hydraulic applications?

Here are a few pressure switches designed to meet the needs of hydraulic applications and the types of systems where they are commonly used.

Key takeaways for choosing the best hydraulic pressure switch

• Hydraulic pressure switches must be designed to handle pressure spikes, vibration, and harsh operating environments.
• Overpressure protection, rugged construction, and environmental sealing are some of the most important selection criteria.
• Mechanical pressure switches with piston-actuated designs are best for rugged hydraulic systems that prioritize durability and cost-effectiveness.
• Watertight switches are commonly used in outdoor or washdown hydraulic environments where moisture protection is critical.
• Choosing the right pressure switch can improve hydraulic system reliability, safety, and equipment life.

Ready to learn more? 

Now that you know what to look for when choosing a pressure switch for hydraulic applications, the next step is selecting a solution that matches your operating conditions, pressure requirements, and environmental challenges.

If you have questions, contact us to speak with a product expert. You can also explore the related resources below to learn more about hydraulic instrumentation, pressure switch technologies, and environmental protection considerations.

In the meantime, download our solutions guide to learn common mistakes people make when choosing pressure instruments.