Retrotec Commercial 441 and 451 DucTester - Manual (Page 46)

Page 46 of 56
©Retrotec Inc. 2015
Appendix C:
U.S. Measurement Procedure for CFM at Test Pressure
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 of 83.21
CFM @ 4.0000 in WC on Channel B.
Notice that NO square footage is displayed in lower
left of screen