Fisher N551, N851-10, N851, N851K-10, N551-16 Instruction Manual

Instruction Manual

September 2015

Types N551 and N851

Types N551 and N851 Snappy Joe™ Emergency
Shutoff Valves

WARNING

!

Failure to follow these instructions or to
properly install and maintain this equipment

could result in an explosion and/or re

causing property damage and personal injury
or death.

Fisher® equipment must be installed,
operated and maintained in accordance
with federal, state and local codes
and Emerson Process Management
Regulator Technologies, Inc. (Emerson™)
instructions. The installation in most
states must also comply with NFPA No. 58
or ANSI K61.1 standards.

Only personnel trained in the proper
procedures, codes, standards and
regulations of the LPG or anhydrous
ammonia (NH3) industries should install and
service this equipment.

Figure 1. Type N551 in Closed Position

Introduction

Scope of the Manual

This manual provides installation and maintenance
instruction for the Types N551 and N851 Emergency Shutoff
Valves and Accessories.

Description

Type N551 Snappy Joe (Figure 1) emergency shutoff valve is

UL® Listed for service in Propane or Anhydrous Ammonia (NH3).

Type N851 emergency shutoff valve is intended for all other
compressed gas service. Reference to Type N551 also refers to

Type N851 unless otherwise specied.

UL® is a mark owned by Underwriters Laboratories.

www.fisherregulators.com

The valves may be installed on both ends of transfer hoses
where the hose connects the bulk plant piping to the bobtail,
transport or tank car. They provide a quick way of shutting

off gas ow in the event of a hose rupture and meet the

requirements for such service when correctly installed with
a remote release and proper piping support. The Type N551
valve is lever operated, latch-open and quick closing valve. A
fusible element in the latch melts if the temperature reaches
212°F / 100°C, allowing the valve to close.

The following accessories are also covered:
Type P164B – Cable Release Assembly

Type P327D – Remote Pneumatic Release Assembly

D450343T012

Types N551 and N851

Specifications

The Specifications table lists specifications for the Types N551 and N851 valve which is designed for butane, propane
or NH

service at ambient temperatures. Contact your local Sales Office if the valve is to be used on any other service,

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fluid, compressed gas or temperature condition.

TYPE BODY SIZES, NPS*

N551-10, N851-10, N851K-10

N551-16, N851-16, N851K-16

N551-24, N851-24, N851K-24

Maximum Inlet Pressure: 400 psig / 27.6 bar

1. FFKM (Kalrez®) gasket and seals.

2. The pressure limits in this Instruction Manual and any applicable standard or code limitation should not be exceeded.
* Nominal Pipe Size.

Operation

(1)

(1)

(1)

CAUTION

1-1/4 FNPT 150 / 568

2 FNPT 295 / 1117

3 FNPT 850 / 3127

(2)

Temperature Capabilities: -20 to 160°F / -29 to 71°C

Installation

Shutoff Direction

The valves shall be installed in the fixed piping between a

The Type N551 handle and shaft may break if

the valve is forced open against the gas ow

and before pressure is equalized on each
side of the main valve disc.

storage tank and the transfer hose connection at the truck or
tank car loading/unloading area. They can be placed in a line
used either for filling or withdrawing from the storage tank
(or both). The valve shall be installed to shutoff flow from the
tank towards the hose, enabling the valve to control product

To Open a Closed Valve:

loss in case of a hose break.

Close a shutoff valve downstream of the Type N551. Pull
the Type N551 handle counterclockwise. There will be an
opening as inlet pressure helps hold the valve disc closed
against the seat. The initial opening force on the handle
opens a pilot valve in the main valve disc, permitting
pressure to build-up downstream. When differential pressure
across the main disc has been reduced, the Type N551 can
be opened without further difficulty by continuing to lift the
handle to the open position. When the handle is fully open
(handle perpendicular to the pipe) the latch engages to hold
the valve open.

The Type N551 valve is a spring closed (aided

by pressure) and shutoff ow in one direction

only. THE NAMEPLATE FLOW ARROW SHOWS
FLOW DIRECTION FOR VALVE SHUTOFF (see
Figure 6). The arrow shall point to the hose

connection. Improper ow direction will not
shutoff ow through the line.

When installed in horizontal piping, install with the nameplate
up. The valve can be installed in vertical piping with the flow

CAUTION

arrow pointing to the desired flow direction for valve shutoff.
In some cases the normal flow through the valve may be

Because the valve is spring closed (aided by

opposite the shutoff direction (like a back check valve).

pressure), the handle can snap down with
considerable force when closing. Keep hands

and ngers away from the handle as it closes.

To Close an Open Valve:

Pushing the handle down (handle parallel to the pipe) will
close the valve.

From a remote location, pulling on the remote cable or
exhausting pneumatic pressure from the Type P327D will retract
the plunger allowing the Type N551 to close. If emergency
conditions cause the fusible element to reach a temperature
of 212°F / 100°C, the element, which attaches the handle to
the shaft, pulls apart and allows the valve to close.

Bulkhead Protection

The valve should be installed near the hose connection, but
shall be positioned so that any undue strain resulting from a
hose pull cannot shear the valve or its inlet piping from the
storage area piping. The piping shall always be firmly supported
and anchored to be sure of meeting the requirement.

One preferred method of installation is shown in Figure 2
where the pipe connection to the valve and to the hose
coupling is securely anchored in a solid bulkhead.

A bobtail truck can provide enough pull on the hose
connection to cause a break in the system. That break must
not occur between the Type N551 and the storage tank.

PROPANE FLOW AT 2 psi / 0.14 bar

DIFFERENTIAL, GPM / l/min

WARNING

!

®

Kalrez

is a mark owned by E.I. Du Pont de Nemours and Co..

2

HOSE CONNECTION

Types N551 and N851

12 / 305

OR MORE

HOSE CONNECTION

T20874

Figure 2. Typical Installation of Type N551 Using Remote Cable Release

Fusible Element Location

A fusible element that will close the Type N551 shall be located
within five feet of the hose connection. If the Type N551 is placed
within five feet of the hose connection, this requirement is met.
If not, an additional fusible element must be provided near the
hose coupling which will activate a remote release.

Remote Release Installation

In all installations a remote release shall be connected to the
latch on all emergency valves at the bulkhead. The remote
release has to extend to a place where it can be easily reached
to close the Type N551 valve(s) in the event that an emergency
makes the valve(s) inaccessible. The remote release shall
shutdown all emergency valves when activated. Remote
release activation may be by cable or pneumatic hook-up.

Cable Hook-Ups

WARNING

!

Remote release cables shall be installed so
that they will close the Type N551 valve(s)
when pulled from the farthest remote location.
Cable shall operate smoothly, over pulleys
and/or through conduit. Do not kink cable or
run cable around sharp corners. If installed
in conduit, keep water out of conduit. Frozen
water, dirt or dried mud in the conduit will
render the remote release inoperable.

Remote releases used on Type N551 valve
shall not:

(a) be made from plastic or ber rope;

(b) have any kind of fusible link which could

melt and prevent the cable from pulling
the Type N551 latch.

NAMEPLATE UP

EMERGENCY SHUTOFF
VALVE TYPE N551

REMOTE CABLE TO
SAFE LOCATION

FIXED PIPING

In. / mm

To provide a remote release, aircraft cable can be connected
to the short looped cable on the valve and run to the remote
release point over pulleys or through conduit. Adjust the cable
so that minimal pull is required to close the emergency valves.

Type P164B Cable Installation

To connect a Type P164B remote release assembly, which is
supplied with 50 ft. / 15 m of cable:

1. Run the inner cable and housing assembly to the
remote release point. Leave enough slack on each end
for a smooth, flowing path, without sharp bends in the
cable, between the Type N551 latch block and remote
release handle.

2. If it is necessary to cut the cable to a shorter length,
pull about one foot of inner cable from the Type N551
latch block cable end (end with the 3/16 x 1/2 in. / 4.8
x 13 mm long cylindrical cast fitting, see Figure 3) from
the housing.

At the remote release end (other end of inner

cablehousing assembly), cut the housing and inner
cable at desired length. Push the excess inner cable
back through the housing so that the bare cable extends
from the remote release end.

3. Close the Type N551 valve. Handle parallel to pipe.

4. If necessary for additional working space, remove the long
end of the external spring from under the latch block. DO
NOT REMOVE SPRING FROM HANDLE.

5. Loosen the slotted screw, Figure 3, on the Type N551
valve’s latch block until the plunger can be pulled from
the latch block.

6. Disconnect the short looped cable and remove it.

7. Insert the Type P164B inner cable end cylindrical cast
fitting through the latch block rear conical hole and connect
the cylindrical cast fitting into the side slot in the plunger.

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