Pressure measurement is used to ensure safe operation and enhance performance in the fluid power (hydraulics and pneumatics) and process industries. Selecting the appropriate measuring range to ensure that the sensor is not destroyed by overloading the sensing element or the process connection is an important part of the design process.
How to Select the Right Pressure Sensor Measuring Range
Step 1: Determine the Typical Static Operating Pressure
The first step is to determine the typical operating pressure of the system. It’s important to consider ideal conditions vs. actual conditions, high or low temperatures and full load operation in determining the typical static operating pressure.
Step 2: Determine Typical Dynamic Operating Pressure
Next, examine the dynamics of your system including the impact of starting or stopping pumps, rapid opening or closing of valves or external dynamics that impact the system (such as mechanical impact onto hydraulic systems, e.g. dropping rocks into a bucket of an excavator, sudden stops of moving vehicles, and so forth).
Determine your required level of accuracy during these events. If all these events are typical operating conditions and require the full accuracy of the sensor, the measuring range of the instrument needs to cover the maximum possible pressure (more than just the safe overpressure range). It’s also important to take a look at the response time of your sensor and your electronics to make sure that you are able to capture and control effectively during these pressure spikes.
If high accuracy measurement of pressure is not required during dynamic pressure spikes, it is sufficient that those pressure levels are covered by the safe overpressure range.
Step 3: Determine any Exceptional Operating Circumstances
It is also important to determine any exceptional circumstances that may have an impact on the expected static or dynamic pressure in the system. Outside normal operations, machines and processes have to deal with occasional operating conditions that do not require measurement, but which should not damage or destroy the sensor. The only way to ensure this is to select a pressure sensor that has an overpressure range large enough to deal with even the highest pressure levels in such situations. (Make sure that the manufacturers definition of “safe overpressure” covers continuous operation at that level and is not limited to one-time events.)
Exceptional operating circumstances could include start-up or even the manufacturing process of machines and systems (for example, some systems are “over-pressured” during set-up to test for leaks or to speed up filling procedures). Also take into account times of non-operation ( e.g. a refrigeration system that is switched off). Due to the rising temperatures, system pressure may rise to very high levels. The timing of shipment or when systems are in transit (e.g. when shipped from site to site etc.) also needs to be taken into consideration.
You should also take into account that any pressure above the “safe overpressure” limit may lead to a burst sensor or a leaking system and will definitely have an impact on the durability and measuring performance of the sensor. If the safe overpressure limit is exceeded even only once for a short period of time, the accuracy and durability of the sensor may be compromised. The sensor needs to be replaced as future performance can no longer be guaranteed.