Retrotec Blower Door - Manual (Page 51)

Page 51 of 87
©Retrotec Inc. 2015
calibration which would test the calibrated fan at the top, middle and bottom of each range and determine the error
at each test point. This Complete Calibration is an expensive test to perform because to do it properly requires over
$100,000 in test equipment, (which is why it’s expensive). For many applications testing on one range regularly is
the best option. If the equipment is out more than 10 to 15%, the equipment should be sent back to the
manufacturer for a complete calibration test.
A field verification check on the gauge described in the DM-2 and DM32 manual should be done prior to performing
this check.
To perform a field calibration using a doorway
1. Install cardboard with a 20 x 20 inch hole in the upper part of a doorway in a room with all exhaust and
supply registers sealed. A square hole is easier to cut accurately compared to a round hole but the round is
supposed to work better although we have never noticed much difference.
2. Set Time Averaging to 10s and Press the [@] key
until “@50.0 Pa” appears.
3. Perform a Door Fan test on the room and record
the EqLA at 50 Pa with the hole open and again
with it sealed.
4. Subtract the first result from the second result
and the value should be 400 sq in (at least +/-10%
and sometimes within 5%). This is about 3100
CFM50 and even though EqLA is used the gauge is
merely doing the math to display CFM at area.
The same check can be performed with the field
Verification Plate, which can be purchased for the
Modular Door Panel system.
A field calibration can also be performed by using the optional Flex Duct
and a field Verification Plate, or a piece of cardboard with a 400 in
2 hole cut
into it.
To perform a field calibration using a Flex Duct
1. Secure the Flex Duct to the outlet side of the fan.
2. Attach a panel to the open end of the Flex Duct with a 400in 2 (20 in
X 20 in) hole cut into it.
3. Run a blue tube from the gauge (blue port) to the panel, and insert
it into the Flex Duct.
4. Perform a Door Fan test on the flex duct and record the EqLA at 50
Pa with the hole open and again with it sealed.
Figure 33: Flex Duct attached for calibration check.
Figure 32: Homemade verification plate.