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The control of fluid dynamics is essential to
ensure efficient and safe use of pumping systems. Uncontrolled fluid in motion
can physically destroy a pumping system including the pump, piping, valves,
meters, back pressure valves, rupture disks and other in-line instrumentation
and equipment.
A pump puts fluid in motion by adding energy to it. This kinetic energy,
observed as pressure, is carried in the fluid and slowly lost into the
piping system through friction. When the fluid in motion is quickly stopped or
started, the kinetic energy is released in the form of a pressure spike.
This occurs because fluids are not compressible and, therefore, transfer rather
than absorb the shock of the sudden pressure change. This "water hammer" effect
is similar to a hammer hitting a concrete wall - some energy goes into the wall
and a little is lost to friction but, most goes back into the arm vibrating the
hammer out of the hand.
Positive displacement pumps and quick closing valves both start and stop fluids
that are in motion. Positive displacement pumps derive their pumping action by
capturing a given amount of fluid in a chamber and pushing it out the pump's
discharge. Each pump cycle includes a suction stroke during which fluid flow is
stopped. The stroke rate of a pump can reach into the hundreds and even the
thousands per minute. This pumping action produces an acceleration/deceleration
of the fluid creating units of uncontrolled energy, resulting in "pulsation"
observed as pressure spikes.
Quick closing valves start and stop large volumes of fluid in motion. The velocity, volume and
density of the fluid all add to the pressure spike created when the valve is
shut and kinetic energy is released. Without any type of cushion to absorb the
energy a high pressure surge is created, traveling up to the speed of
sound. This hydraulic shock travels as a compression wave back and forth
through the entire pipe system until it is finally dissipated by friction or a
system component fails.
The solution to the problems associated with fluid dynamics in process systems
is BLACOH's line of SENTRY
Pulsation Dampeners & Surge
Suppressors, which may also be referred to as suction stabilizers,
thermal expansion chambers, or auxiliary energy storage chambers.
SENTRY products control fluid energy by minimizing
pressure spikes to produce a smooth, even flow that significantly
increases the efficiency and safety of pumping systems. |
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