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  1. #1

    calibrating pneumatic temp gauge???

    Today, I was going through calibration of the pneumatics on an AHU, I started at the stat, and MA temp transmitter, then the DAT temp transmitter, that's where it beat me up, the DAT was 72, but the gauge read about 120, there was 15 psi at the transmitter, and was bleeding off pressure. I'm afraid the last 15 years of DDC has wrecked my pneumatic skills. I had to take a step back, how do I check the temp gauge calibration, I was shown years ago, but normally the only components needing annual calibration have been stats, transmitters, and receiver controllers. what do you think

  2. #2
    Join Date
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    On the outside of most pneumatic temperature/pressure/humidity gauges are hash marks that represent 3 to 15 pounds of pressure that corresponds with the indicated range of that specific dial.

    Once you have the correct gauge for that particular sensor and the gauge is calibrated, all you have to do is match the two.

    I hope this makes sense but there is a tremendous range of gauges to fit each application and if you are calibrating sensors then you must have the matching gauges for that particular range.

    Note the four different ranges indicated on the gauges. You can purchase one gauge that shows all the ranges possible but once you figure out your range vs output you can use just about any good calibrated gauge.
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    "The American Republic will endure until the day Congress discovers it can bribe the public with the public's own money.
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  3. #3
    Join Date
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    Baton Rouge, Louisiana
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    Depends who makes the gauge. Most pnuematic gauges are throw away and cant be calibrated that I've used. If they can be calibrated look for a screw like on a gauge manifold set or a screw on the back. If you can adjust it, pull the gauge, and set the zero, hook it back up and see if the reading matches what you have. If it does rinse and repeat 3 times, if its not repeatable chunk it and get a new one.

    Nice pics Delta
    Last edited by joey791; 09-23-2010 at 07:42 PM. Reason: posted same time as Delta
    Quote Originally Posted by MatrixTransform View Post
    very soon it is you that will be pwned

  4. #4
    It is a 30+ year old Johnson control system I have an identical Trane Climate Changer with identical controls in the same mechanical room, I changed out the temp transmitter, thinking the orifice was plugged, not allowing the transmitter to bleed off, but no dice. I'll swap the gauge from the transmitter in the other AHU that is spot on, and see what i get for a reading

  5. #5
    Join Date
    Nov 2001
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    Why don' you tell us exactly what the problem is and we can all take it on?
    "The American Republic will endure until the day Congress discovers it can bribe the public with the public's own money.
    - Alexis de Toqueville, 1835

  6. #6
    the discharge air temp is 72 degrees, the temp gauge on the temp transmitter is reading 120, and the transmitter is bleeding off pressure, but i cant get the transmitter dialed in
    Last edited by 1maintguy; 09-23-2010 at 09:37 PM.

  7. #7
    Join Date
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    Canada
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    Is it the 5210 Temp Transmitter ? , needs 20 PSI main supply and have you checked the restrictor , found over the years a bit of dirt in it will mess up the readings.

    Usually they are -40 to 160 F range , output should be around 9.5 PSI at 72F

  8. #8
    Join Date
    Nov 2001
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    Quote Originally Posted by Control Man View Post
    Is it the 5210 Temp Transmitter ? , needs 20 PSI main supply and have you checked the restrictor , found over the years a bit of dirt in it will mess up the readings.

    Usually they are -40 to 160 F range , output should be around 9.5 PSI at 72F
    What Contro Man said.

    But you need to get back to basics first. Exactly what one pipe temp transmitter are you looking at? And what exactly is it's range?

    What exactly do you mean by transmitter? Or dialing the transmitter in? What exactly is the transmitter and what is it's make and model?
    "The American Republic will endure until the day Congress discovers it can bribe the public with the public's own money.
    - Alexis de Toqueville, 1835

  9. #9
    you got it, control man nailed it. it's a johnson control t 5210-7 50-150 degree, 20 psi main, the device is bleeding off, but showing 120 degrees at the temp gauge. actual air temp is 72 .

  10. #10
    Join Date
    Mar 2003
    Posts
    7,326
    check the signal to the gage to see if the pressure corresponds to the temp. make sure the range of the gage matches your control. if all that is ok, there may or not be a calibration screw, probably not.

  11. #11
    Join Date
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    Canada
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    For the T-5210 transmitter in the 50 - 150 range at 72F output to gauge is just a little under 6 PSI.

    Transmitter has a calibration screw , do not touch the sensetivity slider


    I was surprised this INFO is still available on JOHNSONS literature site. Go to page 8
    http://cgproducts.johnsoncontrols.co...84&req=T-5210*

  12. #12
    Join Date
    Aug 2000
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    USA
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    4,992
    Is it missing the restrictor in the line?
    Your poor planning does not constitute an emergency on my part!!!!

  13. #13
    Join Date
    Feb 2009
    Location
    Northeast
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    There should be a test port for the hypodermic needle probe at the 5210. Or tee in a small gauge 0-30# to verify if the gauge or the sensor is out of calibration. There should be some small marks at each pound on the big gauge starting at 3# at the 50F position, 9# straight up, and 15# at the 150F position.

    There is a calibration screw on the T-5210, lookup the T-5210 Product Bulletin on the JCI quick lit site. Replace the restrictor first. There may be calibration screw on the gauge. Sometimes they are on the face. Sometimes there is a slot on the center pin of the gauge and you use a screw driver to turn the pin and hold the indicating needle to adjust. I have seen some fancy process gauges with adjustment screws in the back, but these were very old. (They don't build quality like that anymore).

    You need a "good" gauge to check the actual signal in the tube to know where to start. I used to carry about a dozen cheep 1.5" new gauges in the truck. Add them to any branch line in question with gauge tees. Leave them there for the next visit. Calibration is part of the pneumatic trade. Electronics do not need as much calibration, but need just as much inspection to remain at peak performance.

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