If your hydraulic systems suffer from pressure spikes, your pressure switches may not work as expected. The spikes can trigger the switch prematurely, even though continuous pressures remain below the set point. The result is a hard-to-control hydraulic system plagued by false switching signals.

Fortunately, there’s a simple solution to these spike-induced switching errors: Just add a time delay to the switch. That’s exactly what we did in a recent application.

Off-Road Vehicle Experiences Pressure Transients. In an off-road vehicle, a pressure switch was used as part of a hydraulic monitoring system, which was designed to trigger a warning light in the cabin if it experienced sustained excess pressure. But driving over rough terrain was causing unintended pressure spikes, causing the annunciator light in the crew compartment to constantly switch on and off.

Our engineers incorporated a PC board into the pressure switch that was programmed to delay signal output based on certain adjustable parameters, including the amount of time—down to the millisecond—and whether the signal occurred on the rising or falling pressure. In this case, engineers set the time delay at 3.2 seconds. As a result, the warning light remained off unless a pressure change lasted longer than that.

Pressure Switches For Tough Environments. In addition to integrating time delays, these pressure switches had to be ruggedized for use in an off-road application and are designed to withstand pressure spikes, leaks, temperature extremes, moisture, chemical exposure, vibration and shock loads. These ruggedized features include:

• Proof pressures up to 12,000 psig
• Maximum operating pressures up to 7,500 psig
• Wide temperature range of -40 to 250°F
• High overpressure capability
• High shock and vibration survivability
• Snap-action electrical switch tested to 1 million cycles
• IP67 compliance

To learn more about pressure switch design, download our latest white paper.