SECTION 6
LOW PRESSURE WATER
May 2003
6-6
05148390
6.2.3 Booster Pump
The LP cutting water circuit (refer to Figure 6.2) incorporates several
features relating to the booster pump:
a) Booster pump overpressure protection—relief valve (3) is built into
the booster pump body and is intended to prevent excessive pump
outlet pressure. This relief valve typically operates when the
intensifier is dead-headed.
b) If either check valve (13) leaks, the circuit and booster pump could
be subjected to HP water from the intensifier. Inline relief valve
(10)—provides circuit and booster pump protection in the event of
a leaking check valve (13) at the intensifier.
c) High cutting water supply pressure could result if circulation were
blocked as with dead headed HP water flow. Orifice (7) and check
valve (9) allow a minimal amount of LP water to circulate through
the filter back to the pump inlet, thereby reducing the likelihood of
overheating the cutting water.
d) If temperature of cutting water at the booster pump outlet is too
high, then temperature switch (2) activates an automatic
shutdown circuit in the PLC that stops the main electric motor
(pumps stop rotating). Note that temperature switch (2) is located
on manifold (18) for Q and later T series KMT Waterjet pumps, but
is located on the booster pump for earlier series pumps (see Detail
A, Figure 6.2)
e) If water pressure to the booster pump inlet is too low, then the
pump might be starved, resulting in pump damage. Pressure
switch (17) activates an automatic shutdown circuit in the PLC
when pressure drops below the switch setting. Logic in the PLC
ignors momentary low pressure signals that might result in
erroneous shutdown commands. Typical conditions likely to cause
low booster pump inlet pressure are clogged LP filter or problems
with the customer-supplied cutting water pressure.
6.2.4 Low Pressure System Protection
The booster pump pressure relief valve (3) is adjusted by turning with a
flat blade screwdriver. Turn clockwise to increase pressure or
counterclockwise to decrease pressure. Some booster pumps have and
exposed adjustment screw, while on others the adjustment screw is
accessed by removing an acorn nut.
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