Posted March 1, 201411 yr I have no problem understanding how a mechanical pressure gauge works, but how does a mechanical temperature gauge work? Seems like you'd never get the accurate temperature to the gauge through a little tube that's not insulated.
March 1, 201411 yr capillary tube. Kinda like a miniature hydraulic line... and your dial is actually a pressure gauge The probe has a small reservoir of (older units had a low flash point type fluid similar to ether) and when it warms up, the fluid expands, and then moves the dial. you can't cut the line to shorten, or even bending it too sharp. Ok, according to the post below, there are apparently more than one way to measure 'heat' mechanically. I've been around enough older crap to know that the capillary tube has pretty nasty smelling stuff in it when it's broke. Especially when trying to remove the sensor from a 'well rusted' port! Mechanical pressure gauges are connected directly to the process fluid being measured (i.e. oil). As the process fluid pressure changes the pressure on the bourdon tube also changes which in turn moves the pointer on the gauge. Mechanical temperature gauges also utilize a bourdon tube. They have a sealed capillary tube and bulb assembly that is filled with temperature sensitive liquid that produces a proportional vapor pressure on the bourdon tube. As the temperature changes, the pressure inside the bourdon tube changes, which in turn moves the pointer on the gauge. Edited March 2, 201411 yr by rancherman
March 2, 201411 yr The thermocouple reacts to the differences in temperature by sending electrical signals to the gauge. The gauge then deciphers those signals and turns it into something you can understand. If you're totally stumpted then simply google how a thermocouple works and I'm sure there's ample website which can explain it in simple form.
March 2, 201411 yr Author capillary tube. Kinda like a miniature hydraulic line... and your dial is actually a pressure gauge The probe has a small reservoir of (older units had a low flash point type fluid similar to ether) and when it warms up, the fluid expands, and then moves the dial. you can't cut the line to shorten, or even bending it too sharp. Ok, that makes sense. Thank you!
I have no problem understanding how a mechanical pressure gauge works, but how does a mechanical temperature gauge work? Seems like you'd never get the accurate temperature to the gauge through a little tube that's not insulated.