400
Dixon Sanitary 2014
800.789.1718
Technical
Total Dynamic Suction Lift
(
hs) The static suction lift minus the velocity head at the pump suction flange plus the
total friction head in the suction line. The total dynamic suction lift, as determined on pump tests, is the reading of a gauge on
the suction flange, converted to feet of liquid and corrected to the pump centerline, minus the velocity head at the point of gauge
attachment.
Total Head
(
H) or
Total Dynamic Head
The total dynamic discharge head minus the total dynamic suction head or
plus the total dynamic suction lift.
TDH = hd + hs (with suction lift)
TDH = hd - hs (with a suction head)
Total Static Head
The vertical distance in feet between the free level of the source of supply and the point of free
discharge or the free surface of the discharge liquid.
Tube
A hollow cylinder especially one that conveys a fluid. For sanitary applications a thin wall is implied.
Tube Fitting
A length of tubing formed into a usable shape either welded to an apparatus or welded to ferrules
for use in an apparatus.
Tubing
A piece or length of tube.
Tumble Polish Surface
A uniform finish applied by vibratory equipment to stainless steel, varying from matte grey to
bright, depending on media used. This process may cause work hardening on the surfaces.
Tungsten Carbide
A common hard face seal material available in several grades depending upon hardness and corrosion
resistance. Cobalt and nickel are the two most common binders.
Turbulent Flow
Irregular flow that is characterized by tiny whirlpool regions. The velocity of this fluid is definitely not
constant at every point.
VFD
Variable Frequency Drive. Used to vary the frequency going into a motor, thus varying the speed at which the motor runs.
Vapor Pressure
Below this pressure the liquid being pumped will vaporize.
Vaporize
The fluid passes from a liquid to a gaseous state.
Velocity
A measurement of the speed of the liquid in the system; Velocity = distance/time.
Velocity Head
(
hv) The energy of a liquid as a result of its motion at some velocity V. It is the equivalent head in feet
through which the water would have to fall to acquire the same velocity, or in other words, the head necessary to accelerate the
water. Velocity head can be calculated from the following formula:
H =
V
2
2
g
where g = 32.2 ft/second
-2
V = liquid velocity in feet per second
The velocity head is usually insignificant and can be ignored in most high head systems. However, it can be a large factor and
must be considered in low head systems
Glossary of Terms
Y