NEWS CATEGORIES

 

How to Select the Right Pressure Sensor

Selecting pressure measurement equipment can be difficult since each type offers its own advantages. The right supplier can help you select the best equipment for your application. You should choose a supplier with the knowledge and experience to assist before, during and after the purchase. After you’ve identified the right equipment, in order to obtain accurate measurement, you still need to install it correctly and you will need instrumentation to go with it. Here are some guidelines to help you identify the right equipment for your application.

 

Understand your Application

After you’ve determined that you want to measure changes in the pressure of fluid or gas, one of your first considerations will be whether you are looking for a pressure transducer or transmitter. In basic terms, the difference between a transducer and a transmitter is the output. A transmitter outputs signals in milliamps and a transducer outputs signals in volts or millivolts per volt. You’ll need to think about your testing environment. Will the sensor be exposed to extreme temperature, corrosive liquids, intense vibration, etc.? Other considerations that may influence your final decision are size, cost, availability and special requirements.

 

Define your Capacity Requirements

When considering your capacity requirements, you should start by determining if the pressure range being measured is in the positive or vacuum scale of measurement. You’ll also choose between ranges of PSI, Bar, in H2O, etc. Then you’ll select a pressure type: Gage, Absolute, Differential, or Bidirectional. You must carefully consider the pressure range you’ll be working with and you’ll want to choose a sensor whose capacity most closely fits that range. Choosing a sensor with a capacity much higher than your need will make the uncertainty in your measurement more significant while using a sensor whose capacity is too low introduces the risk of overload.

 

Define your Needs

Do you need a sensor within a certain price range to meet your budget requirements? Make sure you know what you will be gaining/losing by choosing a higher/lower cost sensor. Do you need an extremely long cable? If so, a two-wire loop-powered output pressure transmitter may suit you best as some are accurate with up to a mile of cable with the right supply voltage. There are other output options to consider as well. Digital output will allow options like RS232 and USB. High-level voltage outputs are typically used when transmitting over a distance up to 30 feet, but become unreliable beyond that. Keep in mind that a zero-based output signal (i.e., 0 V to 5 V) does not offer constant feedback at zero pressure, leaving the controller unaware if the system is at operating at zero pressure or if there is a problem with the pressure sensor. In contrast, a 1-5V or 1-6V output option offers a live zero for constant feedback into the controller. Lastly, for its ability to communicate directly with a micro-controller without the need of external analog-to-digital (ADC) converter, frequency output is becoming more common with pressure sensors.

 

Define your Size & Specification Requirements

  • Fitting (miniaturization): Male, female, flush mount, semi flush
  • Cable termination: Cable, Connector, Built-in quick disconnect
  • Minimum accuracy: (% of Full Scale): 0.15%, 0.25%, 0.5%, 1% (higher accuracy units typically cost more and may have longer delivery times)
  • Resolution (accuracy x full scale range): 1, 0.1, 0.01
  • Other requirements: burst pressure, required excitation, nonlinearity, hysteresis, creep, bridge resistance, etc.

 

If you’ve determined you need a connector, you should consider that inline connectors reduce the loading on the connector pins, increasing the life of the sensor significantly, and reduce stress on the back-end of the sensor.

 

Select Instrumentation (if necessary)

If you need an instrument for your application, select it at the same time you select the pressure sensor. This will help ensure the compatibility of the entire system. Don’t forget to purchase system calibration with your order. This integrates your sensor and instrument as one system.

 

These are suggestions to help point you in the right direction when selecting your sensor. Of course, our knowledgeable sales staff is also available to help you select the best equipment for your application. Call today at (800) 344-3921 or emailsales@cooperinstruments.com.