Emerson Fisher N551 User manual

Type N551/N851
Instruction Manual
October 2015
D450355T012
www.fisherregulators.com
Type N551/N851 Packing Removal/Replacement
!
WARNING





󰀨

 
󰀨 

Verify that the Emergency Shutoff Valve is Type N551,
and not the previous version Type N550, by conrming
that it is marked with “1” as shown in Figure 2 below.
Please refer to D450042T012 for Type N550/N850
packing removal/replacement Instruction Manual.
If the Type N551(1)’s operating handle closes slowly
or binds in a “no ow” condition, it could be from
binding in the packing gland area or from external
binding, such as a bent operating handle catching on
the latch block, etc. Check for some type of external
binding rst.
If the binding appears to be internal, it could be from
uneven or over-tightened gland bolts (key 33). Try
loosening these two bolts 1/2 turn each and tap the
shaft (key 15) lightly side to side to align the gland
and follower bearing. Snug the bolts down evenly,
only tight enough to prevent leakage. If this does not
free the handle, the packing must be removed and be
either cleaned or replaced.
Removal of Packing
Refer to Figure 25.
Note









 






 
Figure 1. Type N551 in a Closed Position.
Table 1. Replacement Parts to Order
 DESCRIPTION KEY
RCN551T0012
2 washers 29
Packing stack* 30
O-ring 65
T12851T0012 Spring 28
T12841T0012 Follower 31
* Packing stack includes a black graphite female adaptor, a white Tetrauoroethylene
(TFE) packing ring and a white TFE male adaptor.
Magnalube®-G is a mark owned by Trademark of Saunders Enterprises, Inc.
1. Reference to Type N551 also refers to Type N851.

Type N551/N851
2
1. Remove the operating handle (key 18), fuse
link assembly (key 22) and retainer (key 24) by
unscrewing the bolt (key 23).
2. Take out the two gland bolts (key 33).
3. Turn the gland retainer (key 32) 1/2 turn
counterclockwise, refer to Figure 3.
4. Remove the gland retainer from the gland
(key 27).
5. Holding the valve’s shaft rmly in place, pry out the
gland with a screwdriver, Figure 4.
6. Still holding the shaft in place, work the gland over
the end of shaft to remove the gland, Figure 5.
7. The O-ring (key 65) is on the gland groove.
Remove O-ring as shown in Figure 6. The
O-ring should be discarded and a new one used
when reassembling.
8. Carefully remove the packing stack (key 30) from
the rear of the gland. Use a screwdriver, Figure 7,
to push between the coils of the spring (key 28) to
avoid cutting the packing or scratching the gland.
Figure 3. Turn gland retainer (step 3)
Figure 2. Type N551 marked with “1”
Figure 5. Remove gland (step 6)
Figure 4. Pry out gland (step 5)
Figure 6. Remove O-ring (step 7)

Type N551/N851
3
9. The part shown in Figure 8 will be removed
from the gland: a follower bearing (key 31), a
packing stack (key 30 that includes a graphite
female adaptor, a TFE packing ring and a TFE
male adaptor), 2 washers (key 29) and a packing
spring (key 28).
10. Clean the packing (if it is to be reused), the gland
and the shaft of dirt, grease and paint.



Figure 7. Remove packing carefully (step 8)
Figure 8. Remove packing carefully (step 8)
Figure 9. Replacement parts for gland
   
Magnalube®-G is a mark owned by of Saunders Enterprises, Inc.

Refer to Figure 26.
Note







1. Lubricate a new O-ring (key 65) with Magnalube®-G
grease and install it on the gland (key 27) root,
Figure 10. Note the 2 grooves on the back of the
gland, Figure 11. These 2 grooves must engage the
end of the closing spring (key 25) when the gland is
installed in the body.
2. Insert the gland into the body and slowly turn the
gland while pushing it into place. When the closing
spring snaps in one of the gland’s groove, the gland
ts in the body as deeply as it had originally.
3. Install the packing spring and the two washers into
the gland, Figure 12.
Figure 10. Install O-ring on gland root (step 1)
Figure 11. Grooves at the back of gland (step 1)
Figure 12. Spring and two washers (step 3)

Type N551/N851
4
Figure 14. Install adaptor (step 5)
Figure 15. Lubricate (step 5) Figure 16. Install packing ring (step 6)
Figure 18. Install follower bearing (step 8)Figure 17. Install graphite adaptor (step 7)
Figure 13. Lubricate parts (step 4)

Type N551/N851
5
Figure 19. Follower bearing (step 8)
4. Lubricate the shaft, gland, packing and follower
bearing with a liberal amount of Magnalube®-G
grease, Figure 13.
5. Replace the male TFE packing adaptor with the at
side in, Figure 14, working it over the shaft and into
the gland. Be careful not to damage this adaptor.
Apply a liberal amount of Magnalube®-G grease
on the face of this adaptor, Figure 15, that it will be
trapped under the next ring.
6. Install one TFE packing ring with the female side in,
Figure 16, using the same procedure as in step 5.
Again apply a liberal layer of Magnalube®-G grease.
7. Install the graphite adaptor at side out, Figure 17.
8. Install the follower bearing and press it in place
with the gland retainer, Figure 18. The bearing
will extend about 1/8-in. / 3.2 mm from the gland,
Figure 19.
9. Install the gland retainer over the gland. Turn the
retainer about 1/4 turn clockwise, Figure 20, then let
the spring turn the gland back until it stops.
Figure 20. Turn retainer (step 9)
Magnalube®-G is a mark owned by of Saunders Enterprises, Inc.

Type N551/N851
6
Figure 21. Line up holes (step 10)
Figure 23. Install handle (step 12)
Figure 22. Wind retainer, install bolts (step 11)
Figure 24. Align parts (step 13)
10. Remove the retainer and t it back on the gland so
that the bolt holes line up as closely as possible
with bolt holes in the body, Figure 21.
11. Wind the gland retainer 1/2 turn clockwise and
install the bolts (key 33), Figure 22.
Note






12. Install the handle assembly (key numbers 18,
22, 23 and 24), Figure 23 and carefully open the
valve. If there is binding before the handle goes
fully open, the closing spring has been wound too
tightly. Repeat steps 9 to 11 to get the proper spring
winding before proceeding.
13. If the handle moves freely to the open position, tap
the shaft lightly side to side, Figure 24, to align the
follower bearing. The valve should now be ready
for service.
14. Carefully repressure the line and check for leaks.

Type N551/N851
7
Figure 25. Type N551 Replacement Packing Assembly for 1-1/4 to 2 NPT Bodies
B
B
AB1
B
B
AB1
23
23
33
32
22
24
15
18
31
65
30
2928
27
25
L1 L1 L1
S1
33
32
22
24
15
18
31
65
30
2928
27
25
L1 L1 L1
S1
(1)


1. Lubricant and sealant must be selected such that they meet the temperature requirements.

Type N551/N851
© Emerson Process Management Regulator Technologies, Inc., 2014, 2015; All Rights Reserved
The Emerson logo is a trademark and service mark of Emerson Electric Co. All other marks are the property of their prospective owners. Fisher is a mark owned by Fisher Controls International LLC,
a business of Emerson Process Management.
The contents of this publication are presented for informational purposes only, and while every eort has been made to ensure their accuracy, they are not to be construed as warranties or
guarantees, express or implied, regarding the products or services described herein or their use or applicability. We reserve the right to modify or improve the designs or specications of such
products at any time without notice.
Emerson Process Management Regulator Technologies, Inc. does not assume responsibility for the selection, use or maintenance of any product. Responsibility for proper selection, use and
maintenance of any Emerson Process Management Regulator Technologies, Inc. product remains solely with the purchaser.
For further information visit www.fisherregulators.com
LPG Equipment
Emerson Process Management
Regulator Technologies, Inc.
USA - Headquarters
McKinney, Texas 75070 USA
Tel: [phone]
Outside U.S. [phone]

 
15 Shaft
18 Handle Assembly
22 Fuse Link assembly
23 Bolt
24 Retainer
25 Closing Spring
27 Gland
 
28 Packing Spring
29 Washer
30 Packing Stack
31 Follower Bearing
32 Gland Retainer
33 Bolt (2 required)
65 O-ring
Figure 26. Type N551 Replacement Packing Assembly for 3 NPT Body
AB1
A
A
31
L1
65
L1
30
L1
29
2827
25 18 15
24
22
23 S1
32
33
(1)
®

1. Lubricant and sealant must be selected such that they meet the temperature requirements.