Pressure Relief Valve - Pentair Pool Products SHURflo GMBN2VA Operating Instructions, Performance, Specifications And Parts Manual

SHURflo Operating Instructions, Performance,
Specifications and Parts Manual
SHURflo Heavy-Duty Cast Iron and Bronze
Rotary Close-Coupled External Gear Pumps
Operation (continued)
installed by manufacturer (See
Figure 1).
5. On all standard models, pressure
relief valve is always on discharge
side (See Figure 1).

PRESSURE RELIEF VALVE

6. Standard model rotary gear pumps
are supplied with a built-in internal
pressure relief valve (can be exter-
nally ported). The valve may be
adjusted and used to set system
operating pressure, or used as a
system pressure relief valve to
prevent pump and motor damage
that can occur when discharge line
is closed off. This relief valve is not
factory set. Extended operation
(over one minute) under shut-off
conditions could cause pump to
overheat, leak, and damage itself
or overload motor.
7. To increase the pressure relief valve
pressure setting, loosen lock nut
(See Figure 12, Ref. No. 37), then
turn the set screw (See Figure 12,
Ref. No. 36) in (clockwise). Turning
the set screw out (counterclockwise)
will reduce the pressure setting.
When desired pressure is achieved,
tighten lock nut and reinstall pro-
tective cap (See Figure 6).
Loosen valve lock nut and adjust
pressure with adjustment screw
and tighten lock nut again.
Figure 6 - Pressure Relief Valve Adjustment
8. The pressure relief valve can be
converted to an external relief. This
will allow the relief to dump back
to tank and allow longer periods of
relief without pump damage.
Form L-4087 (12/09)
Bronze Models GMBN2VA, GMBN2VA3, GMBN2VA33, GMBN3VA, GMBN3VA4, GMBN3VA43, GMBN4VA,
GMBN4VA5, GMBN4VA53, GMBN5VB, GMBN5VB6, GMBN5VB63, GMBN6VC, GMBN6VC7, GMBN6VC73
Cast Iron Models GMCV2VA, GMCV2VA3, GMCV2VA33, GMCV3VA, GMCV3VA4, GMCN3VA43, GMCV4VA,
GMCV4VA5, GMCV4VA53, GMCN5VB, GMCV5VB6, GMCV5VB63, GMCV6VC, GMCV6VC7, GMCV6VC73
Remove external bypass
plug cover and discard.
then insert external bypass
relief plug as shown.
Figure 7 - External Pressure
Relief Valve Installation
However, this is not a full-line relief
valve, and in cases where frequent
extended relief valve operation is
anticipated, a full-line external relief
valve should be piped in the dis-
charge line and connected either
back to the tank or well down-
stream of the pump suction inlet
(See Figure 7).
9. To convert the relief valve to exter-
nal relief, remove the NPT pipe plug
from the pump cover (See Figure 12,
Ref. No. 36) and discard. This plug is
next to the relief valve. In the bot-
tom of the NPT hole, there is a sec-
ond drilled and tapped hole. An
optional external bypass plug (See
Figure 12, Ref. No. 39 included)
should be inserted in this hole and
bottomed out. The open NPT port
must now be piped back to the tank
or well downstream of the pump
suction (See Figure 7).
10. Standard models are equipped with
pressure relief valves, and the pump
can be run in reverse, however,
the pressure relief valve will not
function. For continuous reverse
rotation, the cover plate must be
rotated 180˚. This is accomplished
by removing the eight cover plate
screws, rotating the cover plate,
and reattaching the screws. The
pressure relief valve should now
be on the opposite side. This will
allow operation of the pump with
a functioning pressure relief valve
in reverse rotation.
8
GEAR PUMP GASKET ADJUSTMENT
FOR TEMPERATURE (See Appendix 1)
11. For operation in fluid temperatures
above 120° F, bronze pump models
must have the gasket thickness
adjusted (not necessary for cast iron
models). Use Appendix 1 to identify
pump, temperature and gasket
recommendations for adjusting the
cover clearance prior to operation in
elevated temperatures or viscosities
above 500 SSU.
Failure to adjust pump
cover clearances for
operating temperatures above 120° F will
result in severe pump and/or motor damage.
NOTE: When pumping fluids of high
viscosity (>500 ssu), the required torque
and HP can be reduced by adding a
gasket for increased gear clearance.
MECHANICAL SEAL FLUSH
INSTALLATION OPTIONS
12. These bronze and cast iron pumps
are equipped with mechanical seals
and have been designed with flush
ports because mechanical seals
require cooling lubrication for
long life.
a. For fluids with viscosities less than
2000 SSU, a flush is not necessary,
but the seal cavity must be pre-
filled with either the operating
fluid or a neutral fluid. This is to
ensure seal cooling and lubrication
during start-up (See Figure 5).
Failure to provide
initial seal prime can
result in the mechanical seal overheating
with resulting repair costs.
b. For high viscosity fluids, a flush
will be necessary. The seal must
be cooled and lubricated by a
fluid. In the case of high viscosity
fluids, due to the precision clear-
ances between the gear teeth and
the bronze or cast iron body,
highly viscous fluids will not be
able to adequately relieve the air