ADM Flow Meter
About Flow Measurements
Agilent CrossLab CS ADM Flow Meter Operation Manual
25
About Flow Measurements
When compared with readings from the ADM flow meter,
measurements taken with bubble-type flow meters may show a
difference. This does not indicate a problem with your flow
meter. As a consequence of the ideal gas law, measurements
made with both soap bubble meters and the flow meter are
temperature sensitive. However, bubble-type flow meters add
water vapor to the gas being measured, which introduces error
into the flow rate measurement.
Even when accurately calibrated, soap bubble meters typically
read slightly higher than the flow meter. The higher readings
arise from relatively high concentrations of water vapor present
in the soap bubble apparatus. At room temperature, water
vapor can raise readings by nearly 4%. This unfortunate
property is amplified by the effect of temperature. As the
measured gas or the flow meter itself is warmed, the amount of
water vapor increases, and the readings can be much higher
than the true flow rate.
