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Old 10-01-2018, 09:19 PM   #1
SteveR.
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Default Is it possible to calibrate a Rex-A-Co Gauge?

My gauge indicates 140F when the radiator is at ambient temperature (80F, etc.). Does anyone know if these can be adjusted/calibrated?
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Old 10-02-2018, 09:19 AM   #2
MikeK
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Default Re: Is it possible to calibrate a Rex-A-Co Gauge?

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Yes. The procedure is the same as adjusting any bourdon tube gauge. Disassemble the gauge, being careful not to kink or overly bend/stress the capillary tube.

Simple one-point adjustment entails some combination of changing the needle/sector gear engagement tooth point (or moving the needle on the shaft), bending/shortening/lengthening the linkage between the end of the bourdon tube and the gear frame, and changing the reverse spring bias pre-load, if one is present. Do this with the sensor bulb suspended in a pot of boiling water and check the barometer for an accurate boiling point compensation.

Actual range accuracy adjustment (accurate at two points on the sweep, like boiling and 140) requires a second accurately measured water bath. If you cannot get the gauge to read fairly close (5% ?) at both points the spring rate of the bourdon tube itself vs. the gauge face plate scale comes into play. Here a bit more skill is required. The first go-to in this situation is the reverse-bias spring plate, if the gauge has one.
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