Retrotec Commercial 441 and 451 DucTester - Manual (Page 40)

Page 40 of 56
©Retrotec Inc. 2015
Appendix B:
U.S. Measurement Procedure for Leakage Factor
The Model 400 blower will create a variable flow over a
wide range of pressures. Systems include all the
accessories needed to connect to ducts under a positive
test pressure: the Model 441 and 442. Models 451 and
452 include additional accessories to test under negative
pressure also.
Many U.S. Standards require the test apparatus to have an
accuracy of +/- 7.5% for flow rate and test pressure and
must have a certificate signifying conformance with the
ASME. The Model 40 has a standard accuracy of 3% for
flow and less than 1% for pressure and complies with
ASME, ASTM and ISO standards. Accuracies of 1.5% for
flow and 0.5% for pressure that are NIST traceable are
available with special calibrations but the standard
accuracy is much greater than necessary for normal
testing.
Picture of DM32 display showing Leakage Factor of 12.10
CFM/100 sq ft @ 4.0000 in WC on Channel B.
Notice the duct surface area of 690 square feet is displayed
in lower left of the screen. The actual test pressure is 3.235
in WC but the gauge displays in flow at the specified Test
Pressure of 4.000 in WC
.