PRINCIPAL OF OPERATION:-
Rota meters are the most widely used type of variable-area flow meter. In these devices, the falling and rising action of a float in a tapered tube provides a measure of flow rate Rota meters are known as gravity-type flow meters because they are based on the opposition between the downward force of gravity and the upward force of the flowing fluid. When the flow is constant, the float stays in one position that can be related to the volumetric flow rate. That position is indicated on a graduated scale. Note that to keep the full force of gravity in effect, this dynamic balancing act requires a vertical measuring tube.
Purge meters offer the basic benefits of Rota meters. For purging applications, considerations of special note include:
- A constant-flow DP regulator is used to maintain purge flow rate at a desired level. The regulator may optionally be specified as part of an integral assembly with the meter.
- An optional inclusion of a needle valve in the purge meter makes it convenient to set the desired purge flow rate.
- A simple indicating purge meter requires no external power source.
- The meter is inexpensive and compact enough for OEM mounting on either a panel or the equipment itself.
- Purge meters come in both glass and metal tube variations and can be equipped with high- and/or low-limit alarms.