A pumping system typically requires three valves: an inlet (suction) shut-off valve, an outlet (discharge) shut-off valve, and a check valve between the pump discharge nozzle and the discharge shut-off valve to avoid reverse flow and protect the pump from backpressure. Occasionally, a foot valve can be installed on the inlet pipe to maintain pump prime or to protect it from reverse rotation.
While there are many variations of flexible couplings, they are all intended to function by connecting two shafts, transmitting rotary power and compensating for some shaft misalignment. The secondary features of these couplings can vary, leading to different benefits paired with each type. Some of these secondary features include cushioning shock loads, vibration damping, maintenance accessibility, electrical insulation or conductivity, limited end float capabilities, fail-safe properties and more. Jaw, wrap, sleeve, tire, grid, gear and disc are all different types of flexible couplings used in pump systems.
Application considerations when selecting a coupling include:
transmit required torque at given speed(s)
fit to pump and driver shaft
providing shaft end separation to permit removal of mechanical seal, permit removal of pump bearings and permit lateral offset of pump and driver shaft
accommodating misalignment
providing end float limitation
maintaining the required degree of unbalance at given speed(s)
dampening torsional vibrations
preventing the dispersion of stray eddy currents
resisting corrosive environments
preventing the occurrence of sparks
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