PUMPING TERMS AND DEFINITIONS

PUMPING TERMS AND DEFINITIONS 

PUMPING is the addition of energy to a liquid to move it from one point to another. 

 

RECIPROCATING PUMPS use pistons, plungers, diaphragms or other devices to displace a given volume of liquid during each stroke of the unit. 

 

LIQUID PISTON OR PLUNGER of a reciprocating pump is the moving member that contacts the liquid and imparts energy to it. 

 

SIMPLEX reciprocating pumps are those, which are equipped with only one liquid piston or plunger. 

 

DUPLEX OR TRIPLEX reciprocating pumps are equipped, respectively, with two or three liquid pistons or plungers. 

 

SINGLE-ACTING reciprocating pumps produce on1y one suction and one discharge stroke per cycle. 

 

DOUBLE-ACTING reciprocating pumps produce two suction and two discharge strokes per cycle. 

 

DOUBLE-ACTING are containers built into a reciprocating pump or attached to its adjacent piping to cushion the shock 0£ the reciprocating action and therefore smoothing the liquid flow. 

 

CENTRIFUGAL PUMPS employ centrifugal force to develop a pressure rise for moving a fluid. 

 

IMPELLER is the rotating element in a centrifugal pump through which liquid passes and by means of which energy is imparted to the liquid. 

 

CASING of a centrifugal pump is the housing surrounding the impeller. It contains the bearings for supporting the shaft on which the impeller mounts. 

 

SINGLE-STAGE centrifugal pump is one in which total head is developed by one impeller. 

 

MULTISTAGE centrifugal pump is one having two or more impellers acting in series in one casing  

 

CRITICAL SPEED of a centrifugal pump is that speed at which the rotating shaft corresponds to its natural frequency .At this speed any minor unbalance of the shaft is magnified, and excessive vibration will occur. 

 

ROTARY PUMPS use gears, vanes, pistons, screws, cams, etc., in a fixed casing to produce positive displacement of a liquid. 

 

PACKING is any material used to control leakage between a moving and stationary part in the 

 VISCOSITY is that property 0£ a liquid that resists any £force tending to produce flow. 

 

SPECIFIC GRAVITY of a liquid is that number which denotes the ratio of the weight of the liquid to the weight of an equal volume of water. 

 

SUCTION LIFT EXISTS when the source of supply is below the centerline 0£ the pump. 

 

STATIC SUCTION LIFT is the vertical distance in feet from the centerline 0£ the pump to the free level of the liquid to be pumped. 

 

TOTAL DYNAMIC SUCTION LIFT is the vertical distance in feet from the "center line of the pump to the free level of the liquid to be pumped plus all friction losses in the suction pipe and fittings. 

 

SUCTION HEAD exists when the source of supply is above the centerline of the pump. 

 

STATIC SUCTION HEAD is the vertical distance in feet from the centerline of the pump to the free level of the liquid to be pumped. 

 

TOTAL DYNAMIC SUCTION HEAD is the vertical distance in feet from the centerline of the pump to the free level of the liquid to be pumped minus all friction losses in suction pipe and fittings. 

 

NET POSI11VE SUCTION HEAD required is the energy needed on the suction side 0£ a pump to fill the pump to the discharge valves during operation. 

 

NET POSITIVE SUC11ON HEAD available is the energy in the liquid on the suction side of a pump over and above that energy in the liquid due to vapor pressure. 

 

TOTAL STAT1C HEAD is the vertical distance in feet between the free level of the source of supply and the point of free discharge or to the level of the free surface of the discharge fluid. 

 

TOTAL DYNAMIC HEAD is the vertical distance in feet between the free level of the source of supply and the point of free discharge or to the level of the free surface of the discharge fluid plus all friction losses. 

 

VAPOR PRESSURE Vapor pressure of a liquid at a given temperature is that pressure which is exerted by the vapor released from the liquid when closed in a vapor-tight container