How to Choose the Best Pressure Transmitter for Your Application?
A pressure transmitter, also called a pressure transducer, is a pressure sensing device that converts pressure measurements from gasses or liquids into analog electrical signals. There are a wide range of pressure transmitter types on the market to suit a myriad of applications. Generally, each pressure transmitter is designed with differing aspects that impact how it works and the applications it is best suited for.
When selecting a pressure transmitter, there are five major criteria to keep in mind. To begin, you must become familiar with the most common types of pressure measurements, those of which are absolute, gauge, differential, vacuum, bidirectional, and sealed gauge. Typically, the application will determine which measurement type you require. Once you have made this distinction, you can evaluate what the appropriate pressure range is for your applications.
Determining your pressure range is probably one of the most important decisions you will make because there are two conflicting factors to consider. The first is the instrument’s accuracy and its protection from overpressure. For accuracy, a transmitter’s range should be low, as normal operating pressure is usually around the middle of the range, so that error, which is a fraction of full scale, can be minimized.
The second important consideration are the consequences of overpressure damage as a result of operating errors, faulty design, or failure to isolate the measuring instrument during pressure-testing and start-up. As such, it is vital that the correct pressure range is set and the correct amount of overpressure protection is available. The next factor we are going to cover is the media that the pressure transmitter will be obtaining a pressure measurement for.
The process media that is going to be measured will influence your decision as well. Usually referred to as “wetted parts,” these materials must be chosen for their compatibility with the fluid being measured. In environments with clean, dry air, any material works fine. However, operating conditions using sea-water benefit from high nickel content alloys, such as alloy 718. Other common materials include 316 stainless steel and 17-4 stainless steel.
It is worth noting that fluctuating temperatures or excessive vibration will limit a pressure transmitter’s ability to work optimally. For temperature extremes, thin-film technology is your best option. Furthermore, extreme temperatures can also create errors in the output of the transmitter which are often expressed in percent full scale over 1 degree Celsius.
In terms of high vibration environments, smaller unamplified transmitters work best. Moreover, the transmitter housing should also be selected based on the electrical area classification and the corrosion requirements of the installation. Corrosion protection should be considered if the outside of the housing will be exposed to corrosive liquids or gasses.
If the application is in an area where explosive vapors are present, the transmitter and its power source must be capable of withstanding these environments. This can be achieved by situating them in purged or explosion-proof housings, or by utilizing safe designs. If the transmitter needs to be compact in size, unamplified transmitters are go-to choices.
Pressure gauges are made in varying accuracies, from 0.5% to 0.05% of the full-scale output. For example, higher accuracy is desired to read very low pressures, such as those common in critically demanding applications. With regard to outputs, there are ratiometric, mV/V outputs, amplified voltage outputs, mA outputs, and digital outputs. Take note of each output’s limitations and benefits.
ASAP Aviation Hub is a leading supplier of pressure transmitters for a diverse set of industry verticals, including civil, aerospace, military, among other sectors. With over 2 billion new, used, obsolete, and hard-to-find options on our databases, customers can easily meet rigid time constraints and strict budget parameters. Kickoff the procurement process with a competitive quote on any featured item(s) and see how ASAP Aviation Hub can serve as your strategic sourcing partner!
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