Differential pressure flow switches are used for monitoring flow rates of water, oil, and neutral liquids. The differential pressure flow meter covers a wide range of pipe diameters.

The device operates on the differential pressure principle, where the pressure drop is proportional to the square of the volumetric flow rate in the pipeline. The DDM series flow meters consist of an orifice plate with an opening integrated into a fitting with flange or threaded connection. A robust orifice-based measuring mechanism is integrated into the flow meter (DS31). The differential pressure generates a force acting on a diaphragm against springs that define the measuring range. A switching piston attached to the diaphragm actuates a contact.

The user sets the switching point, which can be adjusted between 30% and 100% of the flow range.

Measurement accuracy depends on stable flow conditions at the measurement point. Straight pipe runs are required: 6× DN upstream and 4× DN downstream (DN = nominal pipe diameter).

Several versions in steel, stainless steel, or brass are available: