TYPICAL UNLOADER INSTALLATION
1 Pressure Gauge
2 Pop-off Valve
(secondary safety relief valve)
3 Pressure Sensitive Regulating Unloader
4 Triplex Plunger Pump
SELECTION
These pressure sensitive regulating unloaders are designed for systems
with single or multiple pumps, solenoid (gate) valves, nozzles, standard or
“weep” guns.
These pressure sensitive regulating unloaders should meet both the
desired system flow (combined nozzle flow rate requirement) and the
designed system pressure.
Notice: Operation below the minimum flow of the unloader causes the
unloader to cycle. Operation above the maximum flows of the unloader
causes premature unloader wear, cycling and prevents attaining desired
system pressure.
INSTALLATION
These unloaders operate properly when mounted in any direction,
however, it is preferred to keep the plumbing to a minimum and the
adjusting handle easily accessible. The best mounting location is directly
on the pump discharge manifold head.
The inlet connections on this unloader are 3/8” NPTF ports and are
located on the left side and bottom. Arrows and the word “IN” are cast
into the body indicating the direction of flow. A new unloader will have
a plug in the bottom port, but this plug can be switched to the left side
port if needed. Liquid from the discharge of the manifold goes through
these connections.
The discharge connection on this unloader is a 3/8” NPTF port and is
located on the front side (hex end). An arrow and the word “OUT” is cast
into the body indicating the direction of flow. Plumbing to the spray
guns, solenoid (gate) valves or nozzles are connected here.
The by-pass connections on this unloader are 3/8” NPTF ports and are located
on the back side and front face. The word “BY PASS” is cast into the body
indicating the direction of flow. By-pass liquid is directed out of this port
and can be routed to a reservoir (preferred method), or to a drain or to
the pump inlet.
OPERATION
These pressure sensitive regulating unloaders hold established system
pressure in the discharge line when the trigger gun is closed or solenoid
(gate) valve is closed or the nozzle is clogged, thus by-passing all
unrequired flow. Squeezing the trigger gun or opening the solenoid
(gate) valve will close the by-pass and return to established system
pressure.
PRESSURE ADJUSTMENT
1. Setting and adjusting the unloader pressure must be done with the
system “on”.
2. Start the system with unloader backed off to the lowest pressure
setting (counterclockwise direction).
3. Squeeze the trigger and read the pressure on the gauge at the pump.
Note: Do not read the pressure at the gun or nozzle.
4. If more pressure is desired, release the trigger, turn adjusting handle
one quarter turn in clockwise direction.
5. Squeeze the trigger and read the pressure.
6. Repeat this process until desired system pressure is attained.
7. Once the desired system pressure is reached, stop turning the
adjusting handle.
Note: Pressure is not set at the factory.
Notice: A minimum by-pass flow of 5% of the unloader rated flow
capacity is required for proper unloader performance. If the entire output
is directed through the nozzle (zero by-pass) the “cushioning” feature of
the by-pass liquid is eliminated and the unloader can wear or malfunction
prematurely.
8. If desired system pressure cannot be reached, review
TROUBLESHOOTING chart.
9. When servicing existing systems, follow adjustment procedures as
stated above.
Note: Do not adjust unloader pressure setting to compensate for a worn
nozzle. Check the nozzle as part of the regular maintenance and
replace if worn.
Note: A secondary pressure safety relief device (i.e. pop-off valve, safety
valve) should be used along with this pressure sensitive regulating
unloader. Final adjustment for the relief valve should relieve at 200 psi
above the system operating pressure.
Note: By removing the check valve and spring, these unloaders can
function as a secondary relief valve.
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Read all CAUTIONS and WARNINGS before commencing
service or operation of any high-pressure system
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