The design of a Custody Transfer Flow Metering needs to consider a lot of requirements coming from all kinds of different parties such as the oil/gas producer, a contractor, the government, notified bodies and the buyer. International and national standards and regulations might have an effect on the design of a metering system also known as the cash machine. Such flow metering systems are complex consisting of flowmeters, valves, instrumentation, analysers and pipework. However due to technology developments the design is changing to more simple, more controlable and maintainable metering systems.