Definition While many control valves throttle in mid-travel positions throughout their operating lives, some applications include a requirement for the control valve to stop, or…

Sliding-Stem – For sliding-stem valves, the ratio of the maximum to the minimum usable Cv is highly variable, but is generally between 20:1 and 100:1.…

Control valve rangeability is a specification that is closely associated with the concept of flow characterization. Unfortunately, the term rangeability is often misused. Definitions Classical…

While a thorough dynamic analysis of the system can be performed to guide the selection of a particular valve characteristic, the use of established rules…

Selecting A Characteristic – To provide linear system gain over the entire operating range of the system, an equal percentage valve characteristic is selected. This…

Typical Pump And Piping System – The objective of flow characterization is to select a valve gain curve that will match with, or compensate for,…

Cage-Guided Valves – In a cage-guided valve, the flow characteristic is determined by the shape of the cage windows, or openings. Figure 41 illustrates the…

The flow characteristic of a control valve is defined as the relationship between the flow coefficient and valve travel as the valve travels from 0…

The rated Cv of a particular style can be included in the basic liquid flow equation to calculate flow (Q). When the flow rate and…

The relative flow capacity of a control valve is indicated by its flow coefficient. The flow coefficient Cv refers to the number of U.S. gallons…