Measurement of air flow at vacuum conditions using small Venturis

Small Venturis were used to measure air flow rates through cigarette-making machines to a vacuum header.

A programmable calculator was used to develop charts for each Venturi. showing flow versus differential pressure at inlet vacuums from 8 in. (203 mm) to 20 in. (508 mm) of mercury. Use of the charts eliminates the need to calculate the flow each time a test is run.

An error analysis indicated that large variations in temperature do not affect the result. The accuracy of the charts is not affected as long as the tests are run at room temperature.

The Venturis, ranging in size from ½ in. (13 mm) to l ½ in. (38 mm) will continue to be used to measure and monitor vacuum requirements of the machines.