399
Dixon Sanitary 2014
800.789.1718
Technical
Static Head
The pressure at any point in a liquid can be thought of as being caused by a vertical column of the liquid which,
due to its weight, exerts a pressure equal to the pressure at the point in question. The height of this column is called the "static
head" and is expressed in terms of feet of liquid.
Stem Torque
The force required at the valve stem to open or close the valve against system pressure and service
conditions.
Suction Head
Exists when the source of supply is above the center line of the pump. Thus the static suction
head is the vertical distance in feet from the center line of the pump to the free level of the liquid to be pumped.
Suction Lift
Exists when the source of supply is below the center line of the pump. Thus the static 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.
Supply Pressure
The plant air supply pressure available to operate a pneumatic actuator. (plant air)
Surface Finish
all surfaced as defined by Part SF of the current ASME BPE Standard and/or the owner/user or
manufacturer and referred in R
a
µin. or µm.
Surge
Also known as water hammer. A rapid rise or decrease of internal pressure. Surge conditions occur for various reasons,
typically, but not limited to: start and stop sequences.
System Curve
A description of what the pump is required to perform. The pump will pump where the system curve
intersects the pump curve.
System Head
The head caused by friction in the piping valves and fittings.
TDH
Total dynamic head. A combination of the suction head and the head being produced by the pump. Discharge reservoir
pressure head + static discharge head + velocity head at pump discharge + total friction head in discharge line.
TEFC
Totally Enclosed Fan Cooled motor enclosure.
TENV
Totally Enclosed Non Ventilated motor enclosure.
Thixotropic Fluid
Viscosity thins with shear.
Torque
A twisting or turning force. Usually measured in inch pounds (in-lbs) or foot pounds (ft-lbs). (Force through
a distance.)
Total Dynamic Discharge Head
(
hd) The static discharge head plus the velocity head at the pump discharge flange
plus the total friction head in the discharge line. The total dynamic discharge head, as determined on pump test, is the reading
of a gauge at the discharge flange, converted to feet of liquid and corrected to the pump center line, plus the velocity head at the
point of gauge attachment.
Total Dynamic Suction Head
(
hs) The static suction head plus the velocity head at the pump suction flange minus the
total friction head in the suction line. The total dynamic suction head, as determined on pump test, is the reading of the gauge on
the suction flange, converted to feet of liquid and corrected to the pump centerline, plus the velocity head at the point of gauge
attachment.
Glossary of Terms
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