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. Within the range of flowmeters that we distribute are the Sierra, Hoffer and Ritter flow meters. Sierra are the only flowmeter company in the world who manufacture capillary mass flow meters as well as industrial insertion meters based on thermal flowmetering principles. Hoffer manufacture turbine meters for gas. Ritter only manufacture gas meters including the laboratory grade TG series and Bellows Gas meters. Listed below are all the flow meters within our range that are suitable for laboratory gases and liquids:
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.
The Capillary Thermal principal of operation is based on heat transfer and the first law of thermodynamics. During operation, process gas enters the instrument's flow body and it divides into two flow paths. The vast majority of the gas flow passes through the Laminar Flow Element (LFE) bypass. A very small portion of the total flow is diverted through a small "Capillary" sensor tube with an ID between .007 to .028 inches. This technology is ideal for gas flow measurement and gas flow control. Flowmeter accuracy: ±1% of full scale. From 0.1 to 4 sccm up to 1000 slpm.
The immersible thermal sensor is completely immersed into the flow stream. As a result, immersible thermal mass flow meters measure much higher gas mass flow rates in harsher environments than capillary thermal mass flow meters. There is very little pressure drop across an immersible sensor, and the flow does not have to pass through the LFE as it does with a capillary thermal mass flow sensor. Available from Sierra in either inline flow bodied or insertion flowmeter styles. In-line mass flow meters from 0 to 0.7 nm3/h to 0-20000 nm3/h, +/-1% of reading; insertion flowmeters up to 72", +/- 2% of reading.
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.
Ritter manufacture a range of volumetric gas meters including the TG series drum-type, BG series bellow type and the unique MGC Milli Gas Counter.
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 batch resolution; +/-0.1 to +/-0.3% accuracy, +/-0.01% repeatability. 0.1 to 7500 l/min. 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.