The SwemaFlow 125D measures both supply and exhaust air volumes from 2 to 125 l/s (7 to 450 m3/h), together with temperature and barometric pressure. The instrument measurement principle is based on a net of hot wires, which gives a good and accurate mean value of the air flow in the capture opening. The value on the instruments display is the average over 2 seconds, with an update of two times per second. Barometric pressure and ambient air temperatures are also measured to compensate the instrument to standard conditions.
Pressure drop compensation
The instrument has a built in facility to compensate for the restriction the hood and measurement grid puts on the fan system. The "back pressure method" takes two measurements, one with a restriction ring in-place and one without, to compensate for the restriction. This is the ideal tool for low pressure ventilation systems.
Air flow scaling
Apart from the "back pressure method" it is possible to show the flow multiplied with a Flow Factor. This can be useful when balancing systems and this factor has been determined via an alternative measurement method such as a series of pitot traverses in a supply duct from a fan.
Range 2 to 125 l/s, 7 to 450 m3h
Temperature 0 to 50 oC
Airflow accuracy 3.5 % indicated value or 0.4 l/s whichever is the greater
Weight 1.975 kg with 300 x 300 mm hood