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

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

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

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

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

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

Figure 25. Type N551 Replacement Packing Assembly for 1-1/4 to 2 NPT Bodies

AB1

2928

L1 L1 L1

2928

L1 L1 L1

(1)





1. Lubricant and sealant must be selected such that they meet the temperature requirements.

Type N551/N851

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: +1 800 558 5853

Outside U.S. +1 972 548 3574



 

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

2827

25 18 15

23 S1

(1)

®



1. Lubricant and sealant must be selected such that they meet the temperature requirements.

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