Germany-based technol- ogy company Kobold Instrumentation has manufactured a polysulfone paddle switch (PPS) that can monitor flow for nominal pipe sizes greater than NW 32.

Kobold develops, manufac-tures and sells instruments for monitoring, measuring and regulating the physical quanti-ties of flow, pressure, level and temperature, which are distrib- uted by process control instru- mentation and specialised systems manufacturer and distributor Instrotech.

Applications of the paddle switch include the monitoring of cooling circuits, dry running protection for pumps, prevention of low water levels, monitoring pipe fractures and the monitoring of lubricant circuits.

The switch units are instal-lable without the use of dia-phragms, sealing bellows, or O-rings, and as they are made from polysulfone, a type of thermoplastic polymer known for toughness and stability at high temperatures, are almost maintenance free. Operation of the unit is clearly visible through the polysulfone housing.
Fluid flow, regardless of direction, deflects the paddle and, over an eccentric, moves a magnet holder fitted to a permanent magnet. The magnet actuates noncontacting, with a dry-reed switch embedded in the switching tube, the company states.

The paddle switch is available with N/O contact or N/C contact. The inlet and outlet pipe section should be about three times the nominal size of the piping. The flow monitor can be fitted in a standard T piece or reducing pipe. Ideally the flow monitor should be fitted in horizontal piping, the company states.

Features of the Kobold PPS include a switching range of 18 ∙/min to 36 ∙/min to 72 ∙/min to 108 ∙/min, an accuracy of ±20% of reading, and a reproducibility of ±3% of reading. Meanwhile, maximum pressure is 10 bar, with a maxi-mum temperature of 105 °C, while the connection is G1, 1" NPT male for nominal pipe sizes larger than NW 32. Other key product features include easy installation, minimal pressure loss and bidirectional features.