On principle, it is possible to utilize our thermal mass flow meters and controllers in the low pressure range. The sensor allows for an accurate flow measurement down to 100 mbar abs (we never verified lower pressures).
In the case of the flow regulators, a the low pressure is most of the time downstream of the control valve. The valves are vacuum-tight. The following must nonetheless be taken into consideration:
- The devices have a larger pressure loss in vacuum operation. The tubing should thus be designed to be as large as possible.
- In vacuum systems there is a higher risk for the forming of condensation which is a problem for the measurement. (The gas must be clean and dry)