Accessories : Low Flow Fan Field Calibration Plate

Retrotec’s Field Calibration Plate for duct testing systems gives you an easy, five minute test to verify the accuracy of your duct testing system. Performing this test monthly will allow you to detect calibration problems early and fix them before they become serious.

The field calibration plate is compatible with Retrotec’s Q32 and R31 duct testing systems. The field calibration plate is cmpletely compatible with the Minneapolis Duct Blaster.

Detailed Duc-Tester Pressurization Field Calibration Check Procedure

1. Tape the Field Calibration Plate to the flex duct flange &
   attach the red tube.
2. Attach the flex-duct to the outlet side to pressurize the
   duct. Install the Mid flow ring.
3. Connect up as if you were testing a duct.
4. Set to “Flow @ 25 Pa”, time averaging to 8 seconds. Adjust
   the speed until PrA reads close to 25 Pa. Allow the flex
   duct to straighten out to its full length.
5. Wait for 30 seconds after fan speed stabilizes.

The depressurization test is the same as the pressurization test, except the flex-duct is mounted on the duc-tester inlet.

If the measured flow of your duc-tester is less than 97 cfm or greater than 106 cfm, our problems checklist will help you to determine a resolution.

Common Problems

The field calibration manual provides a detailed checklist for each of these common problems.

Problem	Problem Frequency	Typical Error	Details
Wrong Range Configuration or Device	Constant	-80% to +400%	Setting the Digital Gauge to the wrong Range Config or Device is the most common error. Often occurs just after a change of Range or Device.
Tubing Connections incorrect	Sometimes	20%	Especially for pressurizing houses and depressurizing ducts, tubes are hooked up incorrectly most of the time.
Plugged tubes	Seldom	20% to 200%	Wide range of errors but not that common.
Leaking tubes	Less Seldom	10% to 50%	Wide range of errors but not that common. Usually the pressure source will restore some leaked away air but if excessive, pressure indications will fall.
Flex duct leaking	Slow degradation	1% to 25%	Very common but small. Always there to some degree. This procedure will identify a leaking duct so it may be patched with duct tape.
Gauge channels read differently	Rare	1% to 20%	One of 2 channels reading differently. Uncommon but could be a big error. If both channels have an identical error, the effect on the result is negligible.
Gauge won’t zero	Rare	1% to 5%	One of 2 channels reading differently. Uncommon but could be a big error. If both channels have an identical error, the effect on the result is negligible. It is the difference between the channels that causes the errors.

Low Flow Fan Field Calibration Plate Photographs