The HFC-Series, HI-Volume Air Flow Calibrators, have eliminated the need for cumbersome orifice plates and water manometers. The HFC-XXC series units utilize a precision machined Venturi tube coupled with a pressure differential gauge giving a direct reading in the volumetric units of your choice (i.e. SCFM @ stp) . The unit is calibrated against an in-line N.I.S.T. traceable laminar flow element. The primary calibrator meets the requirements of MIL Std. 45662A. HFC-XX series units are intended to be used open to air.
The direct meter read-out will indicate the flow in standard CFM, LPM, or CMM at standard conditions (29.92” of Hg and 70º F). Given actual sampling temperature & barometric pressure during calibration, a technician can convert actual flow readings (i.e. ACFM) to standard units (i.e. SCFM) by making a simple calculation using look-up correction factors from tables given in the operating manual.
Depending on orientation at calibration (vertical vs. horizontal), HI-Q offers two HFC models: The HFC-XX is intended for high flow calibrations in the vertical plane, such as seen with the “HVP” style high volume air samplers. Whereas HI-Q’s HFC-SIDE-XX is intended for the calibration of low to high flow rates in the horizontal plane, such as seen with HI-Q’s line of portable continuous duty and grab air samplers.
The HFC-XX series units have a standard 1½” male straight pipe thread (MSPT) which can be screw into most low to medium volume air sampling pumps (ie: HI-Q’s, CF-1001 or CF-901 ). On higher volumetric flow samplers, a user must incorporate an adapter plate. With the use of HI-Q’s FHA-4CF 4” diameter adapter disc, an operator is able to calibrate a unit with a 4” diameter filter holder assembly. The FHA-810CF adapter plate is used to calibrate units with an 8” x 10” paper holder.