helical screw Positive Displacement meters

There are many different types of positive displacement meter, gear, oval gear, sliding vane, nutating disc, oscillating piston, helical screw and many more. All have the same basic mode of operation in that they take a discrete volume of liquid and pass it from the inlet to the outlet without loss or slippage. The better types are capable of ±0.1% linearity over a wide flow range. By nature these devices How to specify liquid flowmeters, particularly for OEM projects 4 The range of Pelton wheel based low flow metering sensors from Titan measure flows from 0.05 to 30 LPM. Units with built in battery powered LCD totalisers have been adapted for use in vending and drinks dispensing machines, and also to monitor beer flow totals in busy bars and clubs. perform better at higher viscosities as the increasing fluid thickness reduces the leakage rate even further and extends the useful operating range to lower flow rates. Globally the most common form of this device are likely to be domestic water meters and the meters found in petrol dispensing equipment. Because of the way these meters operate they often have a highpressure drop, particularly with more viscous fluids, but some types including the oval gear design operate with a very low differential pressure, only millimetres of head in some cases.