Glossary W

Water Horse Power (W.H.P.)

  • The calculated horse power coming out of the pump using the formula WHP = head x gpm/3960


  • A measure of power. 746 watts equals one horsepower.

Wave spring

  • A disc washer used when axial space is at a premium. Does not allow very much axial travel of the seal.

Wear ring

  • Used with closed impeller pumps to restrict leakage from the high pressure side of the pump to the low pressure side. Should be replaced when the recommended clearance is doubled.

Welded metal bellows

  • A seal design used to eliminate the use of elastomers. Excellent for cryogenic and hot applications. Not as effective for hot petroleum applications because of “coking” problems

Wet end

  • The part of the pump that gets wet from the pumping fluid. Includes the volute, stuffing box, impeller wear rings, and shaft or sleeve