Heavy-duty equipment for both indoor and outdoor applications typically requires measuring water or liquid pressure to some degree. This equipment endures harsh conditions and a wide range of temperatures which can lead to water freezing inside pressure transducers, particularly when equipment is idle. Common applications where this occurs are:
- Irrigation systems
- Firefighting equipment
- Snow making equipment
- Food and pharmaceutical processing
When water freezes in this equipment, it causes extreme high pressure inside transducers, potentially up to several thousand PSI. Most pressure transducers, especially lower range sensors, are not built to handle high overpressure conditions. With limited overpressure ratings of 2x or 3x at best, the pressure from frozen water permanently damages many transducers.
What is Overpressure?
Overpressure is the maximum pressure a transducer can tolerate without an impact on performance. Transducers experience overpressure when the pressure value exceeds this limit. Pressure transducers can withstand occasional pressure spikes up to their overpressure rating; even though this is not ideal, the transducer will eventually return to its normal state. However, burst pressure can damage a transducer. Burst pressure is the maximum pressure that can be applied to the positive pressure port without physically damaging the internal sensing component. Enduring burst pressure can rupture the transducer's diaphragm and cause leakage. When a transducer experiences pressure above the overpressure rating but below burst pressure, its diaphragm becomes permanently deformed, leading to an output shift affecting operational performance or accuracy readings.
If a pressure sensor fails due to overpressure, it can cause the entire control system to fail and lead to inoperable equipment. Troubleshooting a failed control system can be time consuming and costly. For systems experiencing periodic pressure spikes, a damaged pressure sensor is not likely the first issue taken into consideration.
Preventing Overpressure Damage
Setra's Model AXD industrial pressure transducer has a high overpressure option to withstand the 
harsh conditions produced by freezing water or unexpected pressure bursts. Built with the option for high overpressure protection up to 10x FS, the AXD is a robust capacitance transducer ideal for applications with heavy-duty equipment. Setra's patented overpressure stop prevents the sensor from bursting while allowing the diaphragm to maintain its shape, making the sensor ideal for applications that have potential for overpressure.
