The first and most important consideration is pressure. A number of questions must be answered to ensure the correct transducer is selected. What is the pressure range that the transducer will measure? What is the maximum pressure the transducer will encounter? What is the potential for over pressure in the system?
When you have answered the questions above that relate to your application, it is recommended to refer to the pressure transducer’s data sheet and locate the values for the following questions - What is the proof pressure? What is the burst pressure? The answers to these questions are readily available online via the manufacturer’s technical data sheets, but a well-established manufacturer will have application engineers available to discuss your application requirements further.
2. Media & Material Compatability
Any wetted surfaces of the transducer must be compatible with the media, which can include motor oil, brake fluid, refrigerants, hydraulic fluids, seawater, wastewater, tap water, oxygen, compressed air, and nitrogen, to mention just a few. Special consideration must be made for harsh media such as ammonia, ionized water, salt water, hydrogen, acids and jet fuel. Also, be sure that the diaphragm, fittings and welds are compatible with the media. Much of this information is provided on the product data sheet, but a reputable manufacturer will have technical support available to answer additional questions you may encounter.
3. Temperature
The consideration of temperature refers to the temperature of both environment and process media. It is important to note that transducers can operate in most environments and process media temperatures. When an application involves high temperatures, the purchaser should open a dialog with the transducer manufacturer to find solutions for seemingly difficult or impossible installations. For example, say you have an application of 300°F steam, but the transducer you’re considering only has a compensated temperature range of up to 150°F. In this case the problem can be solved by taking the line that runs from the steam line to the transducer, put a link to the tubing (even as short as 12 inches, depending on the environment) and that high temperature is dissipated into the atmosphere.
4. Environment
The environment in which the transducer will operate needs to be closely examined. This includes not only temperature and humidity, but also ingress protection. Sometimes the true ingress protection needed for the application is not documented in the design specification and customers create specialized tests for critical components like the industrial pressure transducer. Customers are encouraged to contact their transducer manufacturer to discuss ingress protection requirements.
Other considerations include shock and vibration that the transducer may encounter, especially in more severe applications such as locomotives or fire trucks. If space is at a premium, find a unit with a small footprint. Location and orientation are further installation considerations. The transducer manufacturer may have encountered similar requirements and may have recommendations for your application.
A transducer’s accuracy is the combined effects of its linearity, hysteresis, and repeatability. Accuracy can be found on each model’s specification sheet. A very common accuracy rating is ±0.25 percent of full-scale output. If higher accuracy is needed, models with ±0.10 percent are available.
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