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Jun 16, 2016 6:00:00 AM

What is overpressure and how can it be prevented?

Can’t handle the pressure?

Can you believe that pressure transducers are not always able to handle high pressure? Overpressure, or proof pressure, is a major concern for engineers and OEM designers when assembling machinery and selecting a pressure transducer. Overpressure refers to the maximum pressure value a transducer can withstand without affecting performance; it can also refer to a situation where the pressure value exceeds the limits. Although it is not ideal, pressure transducers can withstand occasional pressures up to their overpressure rating, eventually returning to their natural state. However, pressures that reach burst pressure, the maximum pressure that may be applied to the positive pressure port without physically damaging the internal sensing component, can rupture the diaphragm and cause leakage. Pressures above overpressure but below burst pressure can result in permanent diaphragm deformation, causing an output shift affecting operational performance or accuracy readings.

For example, a 1.5X overpressure rating for a bigstock-Old-Leaking-Pipe-25153142.jpg0-150 PSI device would mean an overpressure of 225 PSI.

Depending on the application, the risks of overpressure vary.

What Can Cause Overpressure?

Causes of overpressure include fluid hammer, unintentional heat applied to the system, and a faulty pressure regulator. Common areas in industrial applications that face overpressure include valves, solenoids, centrifugal pumps, regulators, and the mounting positions of sensors on pipework. The best solution to overpressure is to prevent it from the very beginning when selecting a pressure sensor.


How to Prevent Overpressure?
  • Select a pressure transducer range to handle the maximum pressure range
    • Overpressure Waves- Select a sensor that covers the maximum pressure value in that application
    • Overpressure Spikes
      • Caused by sudden stopping or starting a liquid flow
      • Requires protection device
  • Select overpressure transducer design
    • Design approaches include under-ranging, mechanical stops and pressure reliefs
    • Understand the dynamics of their system and the limits of the transducer
    • Be aware of the interaction of pumps, control valves, balancing valves, check valves, pressure switches, motors, compressors, tanks and other system components
    • Be conscious of pressure swings in your own system. A review of service calls, warranty claims and conversations with service personnel will reveal the causes and ranges of actual overpressure occurrences
  • Select an overpressure adapter
    • Many adapters work by restricting access to the diaphragm using a small hole to restrict pressure entering
    • Other types of adapters include: piston, bladder types, accumulators, labyrinths.
    • NOTE: ADAPTERS FIX TEMPORARY OVERPRESSURE; IT OFFERS NO PROTECTION AGAINST LONG-TERM OVERPRESSURE.

 

The Setra AccuSense Product Line has a patented overpressure stop which stops the sensor from bursting while still allowing the diaphragm to maintain its shape, making the sensors ideal for applications that have a lot of overpressure.

 

CLICK HERE to learn about pressure transducers for engine test stands.

Topics: General Industrial OEM, Test and Measurement, General Industrial

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