Litre Meter specialise in the design, manufacture and supply of flowmeters. The unique Pelton wheel based meter design ensures an inherent reliability which has been proven in more than three decades of operation. The VFF rotary piston flowmeter is used throughout the world for chemical flow measurement. Listed below are all the flow meters within our range that are suitable for liquids and gasses found in aerospace:
Also known as a radial turbine the highly efficient Pelton Wheel meter has some major advantages. The very large blade area compared with the flow inlet port size produces an exceptionally wide range flowmeter which can measure very low flows. The flow through the inlet of the meter is accurately directed onto the rotor which rotates at a speed in linear proportion to the flow rate. A small sensing coil detects the ferrites mounted in the flow meter rotor blade tips as they pass. No drag is imposed on the rotor which assists in the measurement of extremely low flows. Sapphire bearings provide a very low friction mechanically-robust bearing with long life characteristics. Turndown can be as high as 280:1. Ideally suited for low viscosity process liquids measurement up to 2" pipe sizes and larger and up to 10cSt. 0.003 to 500 l/min; ±2.0% of reading (also 1.0%); some models suitable for flow measurement at higher pressure.
Vortex and other types of "oscillatory" flow meters utilize the behaviour fluid oscillations in order to derive flow rate. This technology works by inducing fluctuations in the fluid properties such as pressure, density or viscosity which can be converted into a flow rate. These flowmeters are normally calibrated on water. No moving parts and relatively tolerant to particulate flow these find many applications where temperatures are high or where other more traditional flowmeter technologies are out of spec. +/- 1.5% rate, 1/2" to 8" and insertion.
Inline 'axial' turbine flowmeters are velocity measuring devices - they measure the average velocity of a fluid flowing through the body of the meter. Mounted within the body of a gas turbine flowmeter is a vaned rotor. The rotor is centred on a shaft and allowed to rotate on bearings. The shaft is supported in the housing by tube bundles that also provide a measure of flow conditioning for the fluid stream. Good for gas flow metering particularly at higher pressures. Wide size range and excellent accuracy. 0.15 to 3.5 up to 200 to 12,000 ACFM. ±1% reading - typical. ±0.25% repeatability. Good for water flow metering. Wide size range and excellent accuracy. 0.24-17 up to 3028-56775 litres/min. Overrange 150% intermittent. ±0.25% reading - typical. ±0.1% repeatability.
Positive displacement flowmeters, also known as PD meters, measure volumes of fluid flowing through by counting repeatedly the filling and discharging of known fixed volumes. A typical positive displacement flowmeter comprises a chamber that obstructs the flow. Inside the chamber, a rotating/reciprocating mechanical unit is placed to create fixed-volume discrete parcels from the passing fluid. The helical screw principle uses 2 counter rotating gears to form a continuous constant volume cavity. Versions OMG and OME in steel and aluminium have the best characteristics for batching and optional pole-wheels enable increased pulse output for finer resolution; +/-0.1 to +/-0.3% accuracy, +/-0.01% repeatability. 0.1 to 7500 l/min. Used extensively in aerospace for testing critical component flows (Skydrol etc). The OMK is a stainless steel version suitable for water flow metering; 0.2 to 100 litres per minute, +/-0.5 to +/-2% accuracy, +/-0.1% repeatability.