Problem with FX manometers

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eodman

eodman

Member
Dec 29, 2017
182
11
Cal, United States
I would fill my bottles on the air rifles and always the gauge on the gun didn't match the gauge on the air tank. I replace the gauges on the my Impacts with Huma gauges. I also tried the gauges made by Wikai but they are larger and the plastic lens cover tends to pop off if banged against something. I used the electronics gauge and set all the regulators to 140 bar. I then filled all guns to factory fill points. The first Impact with both gauges by Huma and the pressure gauge read 250 bar the same as fill tank. The regulator read 140 right on the money as set. 

The second Impact pressure gauge is Huma and it reads the same as fill tank gauge 250 bar. The regulator gauge is FX and it reads 150 bar 10 bar higher than what the regulator is set at.

The Wildcat MKll Comp has FX gauge and was filled to 230 bar as per factory spec. The gauge read 235 bar 5 bar higher.

The crown has FX gauges The regulator gauge has been replaced because it was way off, it was replaced with a factory FX gauge. I filled gun to 250 bar as per factory specs and the pressure gauge read 255 bar 5 bar higher. The replaced FX regulator read 140 bar.

I will be replacing all the gauges with Huma when I get a chance. I would recommend you find a way to check the pressure readings on your tank it will more than likely be on the money. Once you know what the fill tank gauge reads you will know for sure what your fill pressure is.



I took an electronic high end test gauge and hooked it up to the fill tanks after I filled them up and let them cool down.
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All of the tanks read as accurate. 
 
High or low end, if used as a standard, calibration is VERY important. For absolute assurance of the readings gauges must be calibrated and certified by measurement against the National Bureau of Standards sources for a significant cost and this certification MUST be repeated within a certain time frame or the calibration and certifications are void. All small gauges built to a minimum price point and most consumer available gauges will be in error by a small to a larger amount. Anytime a gauge only sweeps a small portion of the dial rather than a 270 degree sweep the errors are multiplied by the low resolution of the gauge.
 
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That's why I just use the fill tank guage. I also use a certified electronic pressure gauge to set the regulator and then make a note as to what the gauge reads at said pressure. So I know what difference is between the guage and regulator.

I have noticed that most FX manometers read higher than actual pressure. That may be a built in safety feature. But I think that the guages are just not accurate because as Thurmond said they are on the low cost point.

WE had a saying in the USMC when I was in the poop "Always remember that your equipment was supplied by the lowest bidder."
 
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