Rotary gas meters are deployed over a large measurement range in a wide variety of applications because of their reliability and exactness. Unlike other gas meters such as turbine gas meters and ultrasonic gas meters, a rotary gas meter always measures with superior exactness, as long as the pistons are not blocked.
In case of a piston blockade, there is no gas thruflow as long as no precutionary measures have been made!
The easiest and safest precautionary measure is an automatic bypass valve which is integrated directly into the meter.
An integrated bypass guarantees the necessary security of supply because the bypass automatically opens as soon as the differential pressure in the meter has reached a previously defined value.
All FMR rotary gas meters can be fitted with an automatic bypass.
The mechanism in the bypass operates at a high force level (large membrane and strong springs), and as a result, the bypass is highy reliable over the expected period of service life. Assisted by 2 reed contacts (one closed one opened) the status of the valve can among others, be monitored via volume conversion.
The bypass itself consists of a housing made from anodised aluminium which is attached to the rear side of the meter by means of an interface connection made of stainless steel.
From time to time in isolated cases, the owner/operator opens the inlet or outlet valve too quickly, so that the bypass is sometimes triggered. If this does happen, then the bypass can be reset on location. A removable plug enables access to the reset mechanism.
In the case of a triggered bypass, this can be reset manually after releasing pressure in the meter. To reset the valve, firstly the officially sealed plug for the reset mechanism has to be removed (see illustration).
Now the bypass can be closed again.
FMG offers a range of springs for different set values for the individual differential pressure settings (see technical data).
