Pd pump Systems neslab p/N 000878 Rev. 08/15/96 Service Manual

Figure 26
Figure 25
External Relief Valve
Internal Relief Valve

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37
Internal Relief Valve Adjustment
4. Remove the acorn nut on the side of the pump. Adjust the
pump pressure adjustment screw (under the acorn nut) until
the gauge indicates the value stamped on the pump. If no
value is shown, adjust to 90 PSI (620 kPa) . Turning the
screw CW will increase the pressure setting. Replace the
acorn nut.
External Relief Valve Adjustment
5. Back out the threaded stem on the external relief valve
(CCW). As the setting drops below the internal valve setting,
the gauge will now indicate the external valve setting.
Continue until the gauge indicates 80 PSI ( 550 kPa ) or
desired setting. Tighten the lock nut.
6. The external relief valve is intended for coarse pressure
limiting, not regulation. For precise pressure regulation, an
external bypass type regulator is recommended.
NOTE: The minimum pressure achievable
using the provided external relief valve is
about 35 - 45 PSI ( 240 - 310 kPa). If lower
operating pressures are required, the addi-
tion of an external bypass-type regulator is
recommended. NESLAB sells various EPR
(External Pressure Regulator) kits for this
purpose. Contact a NESLAB sales represen-
tative for information.
Figure 27
Internal Relief Valve

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 Coupling Lubrication
NESLAB has found that providing lubrication to the bronze cou-
pling will extend its useful life. NESLAB installs a heat shrink
sleeve on the motor shaft as a cup to contain the lubricant. If this
cup is still intact, it should be reused. If the cup is frayed or other-
wise damaged, it should either be replaced or removed com-
pletely.
Obtain a piece of ¾" ( 2 cm ) heat shrink tubing. Cut the piece to
1.5" ( 4 cm ) long. Fully seat the tubing on the motor shaft. Heat
evenly with a heat gun. Insert a small glob (pea-sized) of lubricant.
NESLAB uses a molybdenum-based lubricant with the trade name
NEV-R-SEEZ®. This lubricant is intended primarily for use in
automotive exhaust systems to allow future disassembly, and is
commonly available at automotive supply stores. The grease base
will eventually dry up and leave the molybdenum behind as a
lubricant.
The intent is to provide lubricant between the coupling and the
motor shaft. Do not lubricate between the coupling and the pump
slot.
The nylon coupling does not require lubrication.

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