Air pressure gauge vs. hydraulic pressure gauge

Discussion in 'Off-Topic' started by strantor, Jun 30, 2011.

  1. strantor

    Thread Starter AAC Fanatic!

    Oct 3, 2010
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    Air pressure gauges and hydraulic pressure gauges operate on the same principle, correct? bourdon tube expands proportional to pressure, turns a little gear attached to a needle? The question arose when I couldn't find a hydraulic gauge to troubleshoot a hydraulic system so I got the idea to use an air gauge. My boss said it wouldn't work. I tried it anyway. It did work. Afterwards, I went and looked at all the gauges we have in stock. I couldn't find on any of them where it specified air or hydraulic. I think they might be one in the same. We refer to the liquid filled ones as hydraulic gauges and the non liquid filled ones as air gauges; but I seem to remember seeing a liquid filled gauge on an air system before... somewhere....
     
  2. loosewire

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    Apr 25, 2008
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    Were you using air or hydraulic fliud with gauge,where was the gauge located
    in the system. If you have a hydraulic fluid tank full of oil,where Is the gauge
    located In the system.Is your pump electric or Transmission pump.You don't
    need a gauge to lower a truck bed or boom.
     
  3. #12

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    Nov 30, 2010
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    I used my Freon gauges to measure the pressure in an automatic transmission because transmission fluid is "really good oil with some red dye and a lot of detergent" (according to my teacher). Well...oil is used in Freon systems and so it won't hurt Freon gauges. I brazed an adapter, screwed it in, and measured the pressure!

    On the other hand, cheap tire pressure gauges for cars contain a spring, not a Bourdon tube.
     
  4. loosewire

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    Transmission fuild is not good for seals is it. It may work,but what about the seals.
     
  5. shortbus

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    Sep 30, 2009
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    Air, oil and water pressure gages are interchangeable, as long as the pressure you are checking doesn't exceed the gage limit. The oil filled gages are mainly used in "severe" locations. Severe meaning high vibration or fast/pulsing circuits. The oil is mineral oil to dampen the movements of the gage.
     
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  6. strantor

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    I don't have a gauge in front of me to back this up, but if I remember correctly, there are no seals in the gauge. it's just a brass block, with the bourdon tube coming out of it. a dead end.
     
  7. strantor

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    I was measuring the pressure of hydraulic fluid with an "air" gauge
    pump>flow control valve(branch off to directional control valve)>GAUGE>pressure control valve>tank


    electric
    It's for a heated injection mold press, gauge displaying pressure to injection ram. I wanted to install this "air" gauge temporarily to verify that the existing "hydraulic" gauge was reading correctly.
     
  8. someonesdad

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    Jul 7, 2009
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    If there's any trick to using a pressure gauge, it's finding out what the "wetted" parts are made of -- these are the parts that contact the fluid (here, fluid means a gas or liquid). You want to make sure the wetted parts are chemically compatible with the fluid. Otherwise, the typical Bourdon-type gauge doesn't care whether you're measuring a gas or liquid.
     
  9. #12

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    Nov 30, 2010
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    True. All the gauges I have peeked into have Bourdon tubes which are made of brass and solder. Only an acid would bother that kind of machine.
     
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