Your pressure sensor is a vital component of your equipment or system. When properly specified your system will operate safely and to expected performance levels over the design life of the system or equipment, but only if you have the right sensor that’s appropriate for your application.
The wrong pressure sensor can result in equipment damage, worker injury or out-of-specification measurements. So, how can you ensure you choose the right one?
There are many factors to consider when selecting the right pressure sensor. This article will discuss five important considerations that should help you make the best choice for your application.
5 Factors to Consider when Choosing a Pressure Sensor
Keep these factors in mind while making your selection:
1. Materials
The sensor wetted material you choose must be compatible with your process media. If you are using the wrong materials, you may encounter instrument damage, failure or out-of-specification readings over time.
For example, pressure sensors that are suitable for ultra-low-differential-pressure-based airflow measurements are very different than those for high-pressure hydrogen applications.
Ashcroft has a material selector tool available on our website that can help you find what will work best for your process.
2. Shock and Hydraulic Effects
Shock is typically associated with mechanical shock on a piece of equipment or the pressure sensor itself and typically addressed on pressure sensor data sheets. In this case, we refer to hydraulic shock or water hammer, which can occur within fluid-based systems due to a fluid's incompressible nature.
Hydraulic shock or water hammer is the pressure surge caused by a sudden change in the fluid velocity. This effect can be many times the system operating pressure and occur faster than the output can indicate, yet permanently damage the sensing diaphragm /element. Understanding whether this is possible in the system and, if necessary, address in the system or sensor design to ensure long-term reliable pressure sensor operation.
Besides options in the sensor design, technology and calibration itself there are several accessories and other instruments that can help counteract these negative process effects, such as pressure snubbers, pulsation dampeners and capillary lines.
If not properly addressed, this can result in what is seen as a pressure sensor overpressure failure (out of accuracy condition due to an offset of the zero pressure output reading or worse, diaphragm failure).
3. Pressure Reference
The pressure reference (gauge/vacuum, absolute or differential) is the first step in determining which transducer technologies can be used in a design. What pressure do you want to measure? Is the pressure reference to current atmospheric conditions (Gauge reference) or absolute zero pressure (Absolute reference)?
This is particularly important when trying to measure below atmospheric pressure conditions while determining the amount of vacuum. It is critical to know whether the measurement is relative to the atmospheric condition or absolute zero pressure.
4. Accuracy
How a pressure sensor manufacturer publishes accuracy and performance specifications is often referred to as “Specmanship.” Without agreed-upon industry standards in many regions of the world, accuracy can be defined as BFSL, RSS, Terminal or End Point, Total Error Band, or Typical.
With each of the above terms, a stated accuracy of 0.25% can translate differently in many ways. In critical applications, it may be important that Zero and Span output offsets be included in accuracy as the two can add up to an additional ±2% of inaccuracy in some products. Or, if the application is exposed to a wide operating temperature range, does the accuracy statement include the effects of temperature over that range?
In some cases, if an accuracy statement is stated as typical, the question becomes: is it important that a specific accuracy be met or is typical good enough? Also consider field interchangeability, which I will discuss next.
5. Pressure Sensor Interchangeability
Maintain your system’s performance as specified by the equipment manufacturer when replacing a pressure sensor in the field. This specifically relates to whether zero and span offset errors are either included in the manufacturer’s accuracy statements or are corrected during the initial equipment manufacturing process.
Ashcroft includes zero and span errors in our accuracy statement, but many other companies don’t. This can become an issue because the original system performance may not be maintained when replacing a sensor in the field, which has zero and span offset errors that are not corrected at the time of installation.
We don’t like to pressure you, but we have more information.
Now that you know the factors to consider when choosing pressure sensors, you can research the solution that’s best for your application. Keeping these factors in mind can help ensure that you avoid problems and keep your process running with reliable and accurate pressure measurements.
If you want to learn more about pressure sensors, read some of our other blogs:
- How Does Media Temperature Affect Pressure Transducer Performance?
- How Accurate Are Your HVAC System’s Pressure Instruments?
- How Are Pressure Transducers Affected by Hydrogen Permeation?
- How to Protect and Optimize Pressure Transducers on Mobile Hydraulics
- How Much Do Pressure Transducers Cost? (6 Factors Impacting Price)
Feel free to contact us today to talk to one of our industry experts and get your questions answered.
And if you’d like to learn more about the accuracy of your pressure instruments, download our eBook: