Litre Meter supplies a variety of flow meters for oil and gas applications. It specialises in customising a range of flow meters to meet specific customer requirements. A good example of this is flow meters for subsea use, with the ability to work subsea and provide a direct readout or transmission of the signal to the surface. In one example (pictured), there were five of the six degrees of customisation:
The pressure-balanced chamber (PBC) is used to separate the VFF into the measuring element and the pressure vessel. This allows optimised materials for the rotor and chamber to give better flow range and simultaneously enables the use of more exotic materials for the pressure vessel. More units have been constructed in duplex and super duplex that would have proved almost impossible to use for measurement surfaces (due to the tolerances of manufacture).
When Litre Meter separated the meter into two functions - measurement and pressure containment - the use of coatings could be exploited. After careful selection and testing, most of the VFF range is supplied with PVD coating. This remarkable addition enables higher and lower flow rates. For example, the HF66 size is rated at 66L/min maximum. Typically, without coating, the stainless steel rotor could measure down to 5L/min on water. With a coating, the coefficient of friction is reduced and the minimum reduces to 12L/hr, and the added hardness enables over-range up to 130L/min - subject to factory approval.