Pressure Transducer Basics

Q: What is the difference between a pressure sensor, pressure transducer, and pressure transmitter?

A: Please note that these terms are often interchanged without regard to the meaning below, and that the exact definitions may differ from source to source. These are general definitions. A pressure sensor is typically a millivolt output signal, a transducer has an amplified voltage output, and a transmitter offers a 4-20mA output signal.  

 

Read More: Pressure Sensor vs Transducer vs Transmitter

 

Q: What does long term stability mean? How does it affect measurements?

A: Long-term stability is normally associated with the change in zero offset due to aging of component and relaxation of the metallic diaphragm over a period of time. It normally causes the zero reading to go high or low over time. Independent tests carried out have shown this number to be <.25% under the influence of temperature and pressure cycling for 1500hrs.

 

Q: What is the difference between gauge, absolute, and differential pressure?

A: Gauge pressure is referenced to the barometric pressure conditions.  Changes in barometric pressure do not change the output signal of the sensor.  Absolute pressure sensors and transducers are referenced to a full vacuum; the output signal of the sensor will change with changes in elevation and with changes in barometric pressure.  Differential pressure is the difference in pressure between two points; this is commonly used in filtration applications.

 

Read More: Differential Pressure Transducers for Filtration

 

Q: What is a compound pressure transducer?  

A: A compound pressure transducer is a gauge or sealed gauge sensor that is calibrated to emulate an absolute range.  The pressure transducer will measure a vacuum within its calibrated range.  

 

Read More: Compound Pressure Transducers

Mechanical Interfaces

Q: What types of process connections are available for pressure transducers?

A: TE Connectivity (TE) offers various standard connections, typically threaded.  While our standard configurations are available, custom configurations are also possible for OEM applications.  Threaded connections are available in male and female connections and can be designed with tapered seal, O-ring, or metal to metal seals. Higher pressure ranges require the connection to be rated for the pressure as well.  Contact factory for availability.    

 

Common Thread Types: NPT, SAE / UNF, BSP, Metric, DIN standard

Material Compatibility

Q: What is the material compatibility of TE pressure transducers?
A: TE Connectiviy (TE) manufactures pressure transducers from various materials including 17-4 PH stainless steel, 316L, Alloy 718, Alloy C276, and Titanium. Here are some general guidelines on material compatibility. For more specific information, contact us.

  • 17-4 PH Stainless Steel - hydraulic fluid, air (nitrogen, oxygen, etc), natural gas, freon, paint, steam, plastic molding, diesel fuel, CO2
  • 316 L Stainless Steel - hydrogen*, chlorinated water, ammonia refrigerants, petroleum products (crude or processed)
    *Krystal Bond Technology
  • Alloy 718 / C276 - High H2S content gas, salt water / sea water, high temperature liquids and gases
  • Titanium - Medical devices in contact with bodily fluids

 

Read More: Pressure Transducer Materials

 

Electrical Interfaces

Q: What types of electrical interfaces are available on pressure transducers?

A: The electrical interface is dependent on the product selected.  Certain products, due to hazardous location services or IP ratings, require specific electrical connections.  TE Connectivity (TE) manufactures pressure transducers with integral connectors, in-line connectors, and cable options.  Standard and custom designs are available. 

 

 

Common Electrical Connection Types: Cable, wire leads, M12x1, DEUTSCH DT04 (3 and 4 pin), PT06A 6 pin, DIN 43650 A/B/C, and Packard Metripack 150

Output Signal Selection

Q: How do I choose the best output signal?

Piezo resistive elements are connected in a Wheatstone Bridge configuration.  As the applied pressure varies, the bridge provides a varying differential voltage output to an electronic amplifier.  

 

Selecting an output signal requires an understanding of the application, environment, supply voltage and its regulation, and system capabilities to read and process the signal.  TE Connectivity (TE) offers various analog and digital output signals for its pressure transducers, including our wireless sensing capabilities.  

 

Common Output Signals: 4-20mA, 0.5-4.5V, 1-5V, RS-485 with SDI12, Protocol, 10mV/V, 20mV/V, 0.5-2.5V, 0-10V

 

Read more: Voltage Output Pressure Transducers

Hazardous Area Approvals

Q: Does TE Connectivity offer pressure transducers with hazardous location approvals?

A: Yes. TE has a full portfolio of international approvals for products between 0-1 to 20,000 PSI.  

 

Common Approvals and Ratings: Explosion-proof (flame-proof), intrinsically safe (ex proof), non-incendive, CSA Single Seal, ATEX, IECEx, AMSE B31.3 (CRN), IEC 61508 (SIL2), ABS, DNV/GL, CE