Maintenance - Fisher N551 Instruction Manual

Types N551 and N851
BULKHEAD
TO TRUCK
T20995
3. Leave enough slack in the cable to allow the Type N551
lever to move freely but not close during normal hose
movement or hook-up.
4. Run the cable along the hose. Tape or secure it to
the hose. Fasten the cable securely to the "truck" end
hose connection.
When the hose stretches more than the amount of slack left
in the cable, the tightening cable will pull the lever down and
close the Type N551 valve.

Maintenance

!
Only qualified service personnel should
attempt to repair these valves. Before starting
any type of repair, close off the upstream
valves and remove all pressure from both the
inlet and outlet of the Type N551 Emergency
Shutoff Valve.
At least once a month, inspect and check the
following things:
1. See that the remote release is properly connected,
works freely and is not worn. Operate the release to
make certain it closes the valve. If the valve closes
6
HOSE CONNECTION
12 / 305
OR MORE
Figure 5. Motion Release Cable Installation (Optional)
WARNING
FIXED PIPING
NAMEPLATE UP
EMERGENCY SHUTOFF
VALVE TYPE N551
1 / 25
CABLE "S" HOOK
slowly, packing replacement (refer to Type N551
Packing Removal/Replacement Instruction Manual,
D450355T012) may be required.
2. Make sure that the lever, latch and release are
working smoothly. The latch parts and lever are easily
accessible for replacement or repair by removing the
securing bolts.
3. Check for packing and joint leakage.
Replacing Internal Parts
Verify that the Emergency Shutoff Valve is Type N551 and
not the previous version Type N550 by confirming that it is
marked with "1" as shown in Figure 7.
Type N551 can be repaired in the field. However, due to the
special fire resistant seals and assembly techniques, repairs
should be done only by trained personnel. If repair should
become necessary, contact your local LPG Equipment
Distributor for information and assistance.
Only parts manufactured by Emerson™ should be used for the
repair of Fisher Type N551 Valve. Be sure to give the complete
®
type number of the Type N551 when corresponding with your
local distributor.
Type N551 valve that have been disassembled for repair
must be tested for proper operation before being returned
to service.
REMOTE ACTIVATION METHOD,
CABLE OR PNEUMATIC,
ATTACHMENT LOCATION
IN. / mm