While we pride ourselves on the durability of our pressure transmitters, they are still bound by the laws of physics. Even a sensor that is perfectly matched to the application and installed flawlessly will eventually wear out. The flexing of the diaphragm on the sensing element takes its toll and the bonding layers that hold the sensing element together fail after many years of service.
You can increase the longevity of your pressure transmitter by reducing the stress on the diaphragm. One of the best ways to do this is to order a higher pressure range than you really need.
Avoiding Limits
The upper limit on your pressure transducer is the full scale range. Sure, it has overpressure protection (typically 2X if it’s under 10k psi) and burst protection (typically 5X under 10k psi). But the full scale range your order determines both the calibration of the sensing element and the thickness of the diaphragm.
This limit is very critical. When you push anything mechanical to its limits, it will experience a higher degree of stress. Avoiding the limit can reduce this stress and help your pressure transmitter last longer.
If you expect your pressure to be continually at or near the maximum pressure, even under controlled, steady environments, it’s a good idea to order a pressure sensor with a higher pressure range that you really need. It will reduce the stress on the diaphragm, give you a slightly thicker diaphragm, and improve the longevity of the instrument.
Ready For Spikes
In applications where pressure spikes are common – even if they don’t exceed your overpressure rating – a higher pressure range is a smart idea. Again, it has everything to do with frequency. You may be able to order a lower pressure range and still have the necessary over pressure rating, but if spiking is a common event, a thicker diaphragm designed for greater flex will handle the stress better.
The Weakest Link
So it may be a good idea to order a pressure transmitter with a higher than necessary pressure range. Once you do this, remember not to set your expectations by the sensor’s capabilities alone. Like a chain, your maximum pressure rating is only as high as the weakest link. Operating under any other principle is life threatening.
For example, if you have a 20k psi sensor, but your process fitting can only handle 10k psi, you cannot expect to safely pressure up your system to 20k psi. Remember not to let you sensor’s capabilities rule your expectations for safety – unless it’s the weakest link.
Accuracy Concerns
Since error bands on pressure transmitters are directly tied to the full scale range, you can decrease your accuracy by ordering a higher pressure range that needed. The error band of 0.25% of 200 psi is greater than 0.25% of 100 psi. Typically, though, this isn’t enough of an accuracy loss to matter.
Unless it is. It’s up to you to determine how much accuracy loss is acceptable. If accuracy is a concern, talk to us about it.
In fact, if you have questions about pressure transmitter longevity, or pressure range selection, or anything related to pressure measurement, contact us. We’re here to help you measure better!
