Piston Flowmeters of either single or multiple design find widespread use in fuel dispensing and the low flow measurement of light hydrocarbons. Though complex in design, they are sold in large quantities. In the multiple piston design shown below, the pistons are arranged in opposing pairs and connected through a series if cranks to the register mechanism. This arrangement ensures that when one cylinder is ported to the inlet, the opposing cylinder is ported to the outlet so that fluid has to flow through the measuring chambers with minimum leakage. This design introduces significant pulsations into the flow, which are generally not suitable for flow rates above 100 l/min.

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