SMV Variable Area Flowmeter/Switch

The proven KOBOLD flowmeters and switches model SMV-... are based on the principle of the well-known float-type flowmeters except for the conventional tapering measuring tube. These patented instruments are provided instead with a cylindrical flow tube with conical slots around the periphery. 

This eliminates the usual problems of guiding the cylindrical float within a tapering measuring glass.

The novel design including the provision of an appropriately dimensioned annular gap of constant width between the float and the flow tube has enabled the sensitivity to dirt to be considerably reduced. 

The float comprises permanent magnets actuating a bistable reed contact external to the flow circuit, that is, the flowing medium is  hermetically separated from the electrical contact.

In addition it is embedded in a height-adjustable switch housing, thus ensuring that the contact cannot be damaged even by an aggressive atmosphere. As the medium enters the instrument the float rises. Once its magnetic field reaches the contact tips of the reed switch the contact closes. 

As the flow increases the float rises further until it reaches its stop. This prevents the float from going beyond the contact range of the magnetic operating tube, that is, the contact remains closed, thus ensuring bistable switching.

With the models SMV-2... and SMV-3... the magnetic field also activates an external, that is, hermetically separated indicator, as a result of which flows are measured accurately even at high operating pressures. 

The magnetic field and the indicator are designed so as to ensure that the pointer follows even abrupt changes in flow rate.