Best Pressure Sensor for 125°C, 3 bar Environment: Options and Considerations

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Discussion Overview

The discussion revolves around selecting a suitable pressure sensor for an environment with specific conditions: operating between 1 and 3 bar absolute, at temperatures ranging from 10 to 125°C, and 100% humidity. Participants explore options for small sensors, ideally with a digital interface, while considering budget constraints and the need for temperature compensation.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant seeks a small pressure sensor with a port size no larger than 1/4" and expresses a preference for a digital interface, although it is not critical.
  • Another participant questions whether the 125°C temperature refers to the ambient environment or the fluid being sensed.
  • A participant clarifies that the sensor will be mounted on the exterior of a metal vessel containing hot vapor, indicating that the vessel will be close to the same temperature as the fluid.
  • There is a discussion about the meaning of a digital interface, with one participant suggesting it could refer to either a pressure switch or an analog pressure transducer with a digital output.
  • One participant mentions that 125°C is barely achievable with affordable analog pressure sensors and references the ProSense series as an example.
  • Another participant suggests that if fast dynamic pressure changes are not a concern, the sensor could be mounted away from the pressure vessel and connected via a suitable tube, describing common practices from historical steam technology.
  • Concerns are raised about using a pigtail isolation method, as one participant worries it might perturb the system significantly due to the small chamber size.
  • A participant inquires about the required frequency response of the sensor.
  • It is noted that the pressure will vary relatively slowly, with a response time of 100ms deemed adequate by one participant.

Areas of Agreement / Disagreement

Participants express various viewpoints regarding the specifications and requirements for the pressure sensor, with no consensus reached on a specific model or approach. The discussion includes both technical considerations and differing opinions on sensor placement and design.

Contextual Notes

Participants discuss the limitations of sensor capabilities at high temperatures and humidity, as well as the potential impact of sensor placement on system performance. There are unresolved questions regarding the best approach to meet the specified requirements.

JT Smith
I'm trying to find a small pressure sensor for an environment that will be between 1 and 3 bar absolute, 10 to 125°C, and 100% humidity.

By small I mean a port that's no larger than about 1/4" (sorry for mixing unit systems). Ideally I'd like to have a digital interface but it's not critical. And full temperature compensation would be wonderful, but if I have to I can calibrate across temperature and pressure.

What's my best option? I'd love to get away for no more than about $50, but I can probably spend around $150 if I have to. Is this possible?

Thanks in advance.
 
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Is the ambient operating environment temperature reach as high as 125°C or is that the temperature of a fluid or gas being sensed.
 
Both. The sensor will be mounted on the exterior of a metal vessel which will contain the hot vapor. So the vessel itself will be close to the same temperature. But the environment outside the vessel will be room temperature and normal humidity.
 
JT Smith said:
Ideally I'd like to have a digital interface but it's not critical.
How do you mean? Digital as in on/off (above/below a setpoint) - that is, a pressure switch, or an analog pressure transducer with the output coded into some manner of digital format?

125°C wetted is just barely do-able in an affordable analog pressure sensor. Specs for ProSense series pressure sensors as an example.
 
Asymptotic said:
How do you mean? Digital as in on/off (above/below a setpoint) - that is, a pressure switch, or an analog pressure transducer with the output coded into some manner of digital format?

125°C wetted is just barely do-able in an affordable analog pressure sensor. Specs for ProSense series pressure sensors as an example.

I meant a digital interface for reading the sensor would be the simplest but it is by no means a requirement.

Thanks for the link. I was hoping something less expensive might be available but I kind of suspected that would not be the case.
 
If you are not reading fast dynamic changes of pressure then the actual sensor can be mounted away from the pressure vessel and connected by a suitable shaped tube .

Most commonly a U tube with the outer leg longer than the vessel connection leg is used so that gauge is above the level of the actual port . There are several alternative configurations though .

Common practice . First devised in the early days of steam technology for connecting mechanical pressure gauges to boilers .
 
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Nidum said:
If you are not reading fast dynamic changes of pressure then the actual sensor can be mounted away from the pressure vessel and connected by a suitable shaped tube .

Most commonly a U tube with the outer leg longer than the vessel connection leg is used so that gauge is above the level of the actual port . There are several alternative configurations though .

Common practice . First devised in the early days of steam technology for connecting mechanical pressure gauges to boilers .

That was my first thought, to use a pigtail kind of isolation. But I worry this will perturb the system significantly. It's a fairly small chamber.
 
What sort of frequency response do you need from your sensor?
 
The pressure will be relatively slowly varying. A response time of 100ms would be adequate.
 

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