While there are so many flow measurement technologies, not all of them are suitable for custody transfer flow measurement. Preferred custody transfer flowmeters use the Positive Displacement, Coriolis Mass, Turbine and Ultrasonic measurement techniques.

Positive Displacement has long been the de facto method of measurement in large custody transfer applications such as aviation refueling, railcar loading, tanker loading on gantry and ship unloading applications. This is because Positive Displacement is the only measurement principle that directly computes volume by dividing the flow stream into packets as opposed to inferential measurement which is subject to assumption and error due to varying flow.

Positive displacement flowmeters do not require straight runs, are virtually unaffected by pulsating flow and do not degrade in repeatability as long as clean, filtered service is available. Fluidyne also provides its own air separator and filters for maximum repeatability.