Glossary

Term	Other Versions Sort descending	Abbreviation / Acronym	Classification	Definition
Universal Mag Drive		UMD	Viking Pump Model Series	A series of sealless Mag Drive Viking internal gear pumps named such due to their shared dimensions with comparable sized Viking Universal models.
Composite Mag Drive		CMD	Viking Pump Model Series	A series of sealless Mag Drive Viking external gear pumps named such due to their non-metallic, composite construction.
eXtreme Positive Displacement		XPD	Viking Pump Model Series	A series of Viking internal gear pumps constructed to full compliance with API 676 requirements, documentation, and testing.
Maximum Differential Pressure			Pressure Term	The maximum allowable difference between the Discharge Pressure and the Inlet Pressure for a given set of operating conditions. Calculating: Provided by the Pump Selector program or Catalog Performance Curves, but may be increased or decreased depending on the application specifics, pump size, and construction. This may be less than or equal to the Full Bypass Pressure of the relief valve.
Brake Horsepower		BHP	Units of Measure
Hydrostatic Test Pressure			Pressure Term	Pressure to which the pump will be subjected to for a short duration to insure casting, seal, and gasket integrity. Calculating: Hydrostatic test pressures can be to as much as 1.5 times MAWP, but may be limited by other factors such as the seal.
Kilopascal		kPa	Units of Measure	A unit of pressure measurement
Pounds per Square Inch		PSI	Units of Measure	A unit of pressure measurement
Cracking Pressure			Pressure Term	The pressure at which the relief valve begins to open and bypass liquid. Calculating: This value can be given by the customer or established at 10-15% above the maximum differential pressure for pumps with internal relief valves or the maximum discharge pressure for pumps with return-to-tank valves or in-line system valves.
Atmospheres		atm	Units of Measure	A unit of pressure measurement
Rotor			Pump Part	The rotating assembly in a positive displacement pump, typically driven directly by the motor or other driver.
bar		bar	Units of Measure	A unit of pressure measurement equivalent to 100 kilopascals
Idler			Pump Part	A free-rotating part of a rotary positive displacement pump driven by the rotor
Newton Meters		Nm	Units of Measure	A unit of torque measurement
Internal Gear Pump			Pumping Principle	A type of gear pump a drive gear featuring inward facing teeth called a rotor. This rotor turns an offset gear with fewer outward facing teeth called an idler. A crescent shape protruding from the head of the pump creates this offset and seals the pumping cavities formed between the gear teeth.
Millipascal Seconds		mPas	Units of Measure	A unit of viscosity measurement equivalent to 1 centipoise
External Gear Pump			Pumping Principle	A type of gear pump featuring two identical external gears where one gear is the drive gear and one is the driven. The liquid is transferred from between the gear teeth by the rotation of the pump.
Gear Pump			Pumping Principle	Any type of rotary positive displacement pump consisting of gears where the pumping results from the unmeshing and remeshing of gears. The liquid is carried between the gear teeth by the rotation of the pump. Common types of gear pumps include internal gear, external gear, and gerotor.
Gerotor Pump			Pumping Principle	A type of internal gear pump that is driven by the idler gear and does not include a crescent.
Centistokes		cSt	Units of Measure	A unit of viscosity measurement equivalent to 1 millimeter squared per second
Lobe Pump			Pumping Principle	A type of rotary positive displacement pump consisting of a pair of externally timed rotors such that each is driven independently and the rotors are non-contacting. Rotor designs vary but some of the more common types include bi-wing (or scimitar), tri-lobe, and various multilobe designs. Similar in operation to a circumferential piston pump.
Krebs Units		KU	Units of Measure	A unit of viscosity measurement
Gallons per Minute		GPM	Units of Measure	A unit of flow measurement (NOTE: slightly different in US and UK units)
Centrifugal Pump			Pumping Principle	A type of kinetic pump consisting of a rotating impeller in a casing volute. This type of pump transfers rotational energy from the spinning impeller to the liquid.
Gallons per Hour		GPH	Units of Measure	A unit of flow measurement (NOTE: slightly different in US and UK units)
Vane Pump			Pumping Principle	A type of rotary positive displacement pump consisting of a slotted rotor offset in a cam shaped housing. Sliding vanes in the slots of the rotor extend to create pumping cavities, sweep the liquid through the casing, and expel the liquid at the discharge side of the pump as the cam reduces in area and forces the each vane back into its slot.
Liters per Minute		LPM	Units of Measure	A unit of flow measurement
Net Positive Suction Head		NPSH	Units of Measure	The absolute head required at the inlet of the pump to prevent cavitation, noted with suffix "A" for available from the system or "R" for required by the pump. Similar to NPIP.
Liters per Hour		LPH	Units of Measure	A unit of flow measurement
Net Positive Inlet Pressure		NPIP	Units of Measure	The absolute pressure required at the inlet of the pump to prevent cavitation, noted with suffix "A" for available from the system or "R" for required by the pump. Similar to NPSH.
Barrels per Day		BPD	Units of Measure	A unit of flow measurement
Barrels per Hour		BPH	Units of Measure	A unit of flow measurement
Low Viscosity Pump		LVP	Viking Pump Model Series	A series of Viking vane pumps named such due to their ability to handle low viscosity liquids even at high pressures.
Spur Gear		SG	Viking Pump Model Series	A series of Viking external gear pumps named such due to the cut of the external gears.
Gear Pump		GP	Viking Pump Model Series	An older series of Viking external gear pumps which has been largely replaced by the SG Series™
Air Operated Double Diaphragm	AOD, AODD, AODDP		Pumping Principle	A type of pump featuring a pair of opposing diaphragms alternatively expanded by compressed air to expel liquid on the opposite side of the diaphragm. An air valve in the pump shifts the flow of air from one diaphragm to the other resulting in an intake stroke on one side and a discharge stroke on the other. Check valves in the pump prevent the backflow of pumped liquid.
Full Bypass Pressure	Complete Bypass Pressure		Pressure Term	The pressure at which the entire capacity of the pump is bypassing through the relief valve. In other words, this is the maximum differential pressure rating for pumps with internal relief valves or the maximum discharge pressure rating for pumps with return-to-tank valves or in-line system valves. Calculating: Dependent on the valve used, spring used, and capacity of the pump.
Circumferential Piston Pump, External Circumferential Piston Pump	CPP, ECCP		Pumping Principle	A type of rotary positive displacement pump consisting of a pair of externally timed rotors such that each is driven independently and the rotors are non-contacting. Rotor designs vary but the most common type is bi-wing. Similar in operation to a lobe pump.
Centipoise	cPs	cP	Units of Measure	A unit of viscosity measurement equivalent to 1 millipascal second
Foot Pounds, Pound Feet	lb.ft.	ft.lbs.	Units of Measure	A unit of torque measurement
Maximum Allowable Casing Pressure	MACP		Pressure Term	Maximum rated pressure of the pressure containing components of the pump, not including the shaft seal, but including the canister in the case of Mag Drive pumps. Calculating: MACP can be established as the pressure limit of the port connections for most pump models. In the case of Mag Drive pumps, it can be considered as the hydrostatic limit of the canister divided by 1.5.
Maximum Allowable Working Pressure	MAWP		Pressure Term	The maximum continuous pressure for which the pump is designed. Calculating: MAWP can be established as the lowest pressure limit of the following 3 components: 1) Shaft Seal 2) Joint Seals 3) Port Connections
Maximum Allowable Inlet Pressure	Maximum Allowable Suction Pressure; MASP		Pressure Term	The maximum allowable difference between the absolute pressure of the fluid at the inlet port and the absolute ambient pressure. Calculating: Limited by the same factors as Maximum Allowable Working Pressure (MAWP).
Millimeter Squared per Second	mm^2/s	mm²/s	Units of Measure	A unit of viscosity measurement equivalent to 1 centistoke
Cubic Meters per Hour	m^3/hr	m³/hr	Units of Measure	A unit of flow measurement
Discharge Pressure	Outlet Pressure; Discharge Head		Pressure Term	Pressure at the outlet port of the pump. Calculating: Discharge pressure is a function of the system and must be calculated or measured. Measurements can be made at the gauge port on the outlet side of the pump or at a point on the outlet pipe as close as possible to the pump.
Relief Valve, Pressure Relief Valve	PRV	RV	Pump Part	A mechanical device designed to bypass flow in the result of an overpressure condition at the outlet port of the pump.
Inlet Pressure	Suction Pressure; Suction Head		Pressure Term	Pressure at the inlet port of the pump. May be positive or negative. Calculating: Inlet pressure is a function of the system and must be calculated or measured. Measurements can be made at the gauge port on the inlet side of the pump or at a point on the inlet pipe as close as possible to the pump.
Sabolt Seconds Universal (or Saybolt Universal Seconds)	SUS	SSU	Units of Measure	A unit of viscosity measurement
Differential Pressure	Total Dynamic Head; TDH; ΔP)		Pressure Term	The difference between the Discharge Pressure and the Inlet Pressure. Calculating: Differential pressure is a function of the system and must be calculated or measured. Measurements can be made at the gauge ports near the inlet and outlet ports of the pump.