Virtual Labs

When a control valve is installed in a process with where the differential pressure (drop) across the valve decreases with increasing flow, the best trim characteristic to choose for the valve would be:

a: Equal percentage b: Anti-cavitation c: Ported d: Quick-opening

Calculate the necessary Cv rating for a liquid service control valve, given a pressure drop of 24 PSID, a specific gravity of 1.3, and a maximum flow rate of 140 GPM. Assume there will be no flashing or choked flow through the valve.

a: 0.1319 b: 601.5 c: 32.58 d: 7.583

The main purpose of a control valve positioner is to:

a: Improve the precision of the valve b: Alter the characterization of the valve c: Alter the fail-safe status of the valve d: Increase transmitter accuracy

The purpose of valve packing is to:

a: Cushion the valve against harm during shipment b: Seal process fluid from escaping past the stem c: Lubricate the valve trim d: Help reduce cavitation in the valve trim

The definition of split range control valves implies that they are . . .

a: easily re-ranged for different characteristics. b: equipped with quick-acting positioners. c: only used in sets of three. d: calibrated with complementary ranges.

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