Your Manifold Gauges, To Calibrate or Not?

In the HVAC industry (as in many others) we have a wide range of actors that on occasion clash with different points of view on certain topics.

When questioning with respect to Calibrating Manifold Gauges, some of the responses we received evidenced little to no attention to the act of Calibration. Most of these responses came from experienced field techs that overlook this procedure.

The most prominent brands in the market however, recommend the Calibration of the Manifold, with some suggesting it should be done before every use.

Many factors play a role in the Calibration of the Manifolds. Such activities like purging out refrigerant, flushing out with Nitrogen after each use, avoiding hits and bangs when carrying, safely placing the tool in a bag and some other actions can prevent your manifold from losing its calibration.

If you are curious, or need to calibrate your Manifold Gauges, here are some steps to follow:

1) You will need:

a) Manifold Gauge Set

b) Refrigerant Tank at room temperature

c) Thermometer

d) Pressure/Temperature Chart (we like to use the Danfoss Ref Slider, available in App versions

e) Optional: Second Manifold Gauge set for verification

2) Take the temperature of the Refrigerant with which you are calibrating

3) Go to the Pressure/Temperature Chart and locate the pressure reading for the temperature measured for that specific Refrigerant

4) Connect your Low Pressure gauge to the Refrigerant tank and verify. Adjust the manifold gauge if necessary. For this you will need a pocket screwdriver and slowly make the needed correction, clockwise to increase and counter clockwise to decrease the reading on your manifold.

5) If you have a second Manifold Gauge Set, you can place it in series to verify that the readings are the same.

6) Repeat the process for the High Pressure Manifold Gauge.

How often you do this will depend on the usage of your Manifold.

Most recommendations are to calibrate every 3 months.

To understand the importance of Calibrations, take for example a reading on your pressure/temperature chart for R410A. In a low pressure reading, a 5 PSI differential equals a temperature difference of approximately 3-4 degrees F.

We strongly recommend you purchase a good quality Manifold and take the necessary precautions to avoid bumps and bangs when not in use. This will help to keep it from giving you the wrong readings.

So, do you Calibrate your Manifolds?

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