Emerson Spence Type N6 User manual

www.SpenceValve.comwww.SpenceValve.com

Spence Type N6 Differential Pressure Valves

▲ WARNING

Failure to follow these instructions or

to properly install and maintain this

equipment could result property damage

and personal injury or death.

Type N6 differential pressure valves

must be installed, operated and

maintained in accordance with federal,

state and local codes, rules and

regulations and Emerson Process

Management Regulator Technologies,

Inc. (Emerson) instructions.

If the valve vents gas or a leak develops

in the system, service to the unit may be

required. Failure to correct issue could

result in a hazardous condition.

Installation, operation and maintenance

procedures performed by unqualified

personnel may result in improper

adjustment and unsafe operation. Either

condition may result in equipment

damage or personal injury. Only a

qualified person shall install or service

the Type N6 differential pressure valves.

Introduction

Scope of the Manual

This manual provides instructions for the installation,

troubleshooting, maintenance, valve setting and parts

ordering for Type N6 differential pressure valves.

Product Description

Type N6 differential pressure valves are designed

to maintain pump discharge pressures at a constant

differential above a separate source of pressure.

When installed in a boiler feed pump discharge line

Figure 1. Type N6 Dierential Pressure Valves

November 2021

Instruction Manual

VCIMD-16088

as a by-pass valve, a connection from the stream

drum is made to the top chamber of the Type N6.

The desired differential is made by adjusting the

spring. The boiler feed-water pressure will then be

maintained by Type N6 at a constant pressure above

steam drum pressure by modulating the quantity of

water by-passed to pump section. When installed in

a by-pass line across a pumped system, Type N6

will maintain a constant differential of supply main

pressure over return main pressure by modulating the

quantity of by-passed water.

Type N6

Specifications

This section lists the specifications for the Type N6 differential pressure valves. Factory specifications are

stamped on the nameplate fastened on the valve at the factory.

Rated Flow Coe󰀩cient

See Table 1

Materials of Construction

Body: Cast iron

Stem, Disk, Seat Ring, Piston and Spring:

Stainless steel

Sealing Ring: Fluorocarbon (FKM)

Gasket: Graphite

Approximate Weight

See Table 2

Valve Sizes

NPS 3/4, 1, 1-1/4, 1-1/2, 2 and 2-1/2 /

DN 20, 25, 32, 40, 50 and 65

End Connection Styles

NPT and CL250

Pressure Rating(1)

250 psig / 17.2 bar

Temperature Rating(1)

350°F / 177°C

Spring Ranges

5 to 50 psid / 0.34 to 3.4 bar d

40 to 125 psid / 2.76 to 8.62 bar d

100 to 200 psid / 6.89 to 13.8 bar d

1. The pressure/temperature limits in this Instruction Manual and any applicable standard or code limitation should not be exceeded.

Table 1. Type N6 Dierential Pressure Valve Rated Flow Coecients

BODY SIZE FLOW COEFFICIENTS (CV)

NPS DN

3/4 20 7.1

1 25 13.3

1-1/4 32 22.0

1-1/2 40 32.5

2 50 51.0

2-1/2 65 88.0

Table 2. Type N6 Dierential Pressure Valve Approximate Weight

BODY SIZE APPROXIMATE WEIGHT

NPS DN lbs kg

3/4 20 10 4.5

1 25 12 5.5

1-1/4 32 19 8.6

1-1/2 40 26 12

2 50 39 18

2-1/2 65 74 34

Type N6

BOILER DRUM PRESSURE BOILER LEVEL CONTROL VALVE

BOILER WATER FEED LINE

TYPE N6 VALVE

1/4 IN. PIPE

BY-PASS LINE

FEED TANK

FEED PUMP

BOILER

Figure 2. Type N6 Installation Drawing

Principle of Operation

Flow enters the valve such that the initial pressure acts

against the working face of the disk and tends to move

it open. Opposing the opening are the forces of the

differential adjusting spring and the loading pressure

acting on the piston. The differential adjusting spring

force creates the differential between the retained

pressure (supply main or boiler feed water) under the

disk and the loading pressure (return main or boiler

drum) on top of the piston.

Type N6

Startup and Adjustment

1. Type N6 valves are shipped with the adjusting

spring precompressed. This precompression

may result in a differential pressure higher than

desired. Remove adjusting screw cover and

loosen adjusting screw locknut. It is recommended

that the precompression be removed by turning

the adjusting screw counter-clockwise until the

screw turns easily indicating the spring load has

been removed.

2. Open the inlet stop valve gradually until the

Type N6 differential valve takes control as

indicated by the differential pressure gauge.

3. Turn adjusting screw clockwise to increase the

differential pressure and counter-clockwise to

decrease it.

4. With no compression on the adjusting spring the

pump discharge pressure and the boiler pressure

applied to the spring chamber will be the same,

due to the fact that the piston and the disk have

the same area and are balanced. To increase

differential pressure, compress adjusting spring

until desired differential is obtained.

Maintenance

▲ WARNING

To avoid personal injury, property

damage or equipment damage caused by

sudden release of pressure or explosion

of accumulated gas, do not attempt any

maintenance or disassembly without first

isolating the valve from system pressure

and relieving all internal pressure from

the valve.

Installation

▲ WARNING

Personal injury or system damage may

result if this valve is installed, without

appropriate overpressure protection,

where service conditions could exceed

the limits given in the Specifications

section and/or valve nameplate.

Additionally, physical damage to the

valve may result in personal injury or

property damage due to escaping of

accumulated gas. To avoid such injury

and damage, install the valve in a

safe location.

Under enclosed conditions or indoors,

escaping gas may accumulate and be an

explosion hazard. In this case, the vent

should be piped outdoors.

For valve constructions with a spring

case vent, the vent should be kept

open to permit free flow of gas to the

atmosphere. Protect openings against

entrance of rain, snow, insects or any

other foreign material that may plug the

spring case vent or vent line.

All pressure equipment should be

installed in a non-seismic area;

should not be exposed to fire; and

should be protected from thunderbolt

(lightning) strikes.

△ CAUTION

After the valve is in service at operating

pressure and temperature, check all

gasketed joints and re-tighten. Failure to

follow these instructions may result in

damage to gaskets and mating surfaces.

• Carefully clear inlet piping system of foreign

matter such as: welding beads, scale, sand, pipe

compound, etc.

• Allow head room above the valve for maintenance.

• Provide a three-valve by-pass to facilitate

inspection of the regulator without

interrupting service.

• Preferred position for Type N6 valve is in a

horizontal line with spring chamber up and arrow on

body pointing in direction of flow.

• The loading line should be 1/4-in. pipe connected to

the spring chamber tap.

• Avoid damaging effects of foreign matter in the flow

by using Emerson strainer ahead of the valve.

Type N6

Valve Grinding

1. Use fine (grit 400 to 800) compound on the seat,

using light pressure.

2. Check seating by blueing the valve disk bevel face

before reassembling.

3. Clean all parts with kerosene or carbon

tetrachloride before reassembling.

4. Lubricate sealing ring (key 13) with a silicone

lubricant or soap solution to facilitate insertion into

guide area of body. Do not use petroleum base

lubricants on rubber sealing rings.

Dismantling Type N6 Valve

for Cleaning

1. Shut off supply and discharge valves and line from

steam headers.

2. Remove top cap (key 1).

3. Loosen lock nut (key 3) and unscrew adjusting

screw (key 2) until spring tension is released. (This

step can be omitted if setting adjustments cannot

be made after cleaning).

4. Disconnect pressure sensing line from boiler

steam header.

5. Remove the four spring chamber hex head

nuts (key 9).

6. Separate spring chamber (key 6) from the valve

body (key 20). Spring (key 7) and buttons (key 5)

will drop out.

Troubleshooting

1. Failure to Open—differential too high.

a. Differential adjusting spring setting may have

been tampered with.

b. Valve piston (key 14) and sealing ring (key 13)

may be binding.

c. Valve stem (key 18) and bushing (key 19) may

be binding.

2. Failure to Close—differential too low.

a. Foreign material may be between the seat and

disk of the main valve.

b. Line from steam header may be plugged,

restricted or broken.

c. Differential adjusting spring setting may have

been tampered with.

d. Chamber "C" may be dirt plugged or port in

bushing (key 19) may be plugged.

e. O-ring or piston may be damaged and leaking.

To avoid possible personal injury from

spring or pressure-loaded actuator,

make sure that the adjusting screw is

completely backed off or the spring case

pressure is vented prior to disassembly.

Otherwise, the spring load or loading

pressure could forcefully eject the

spring case.

Valves that have been disassembled

for repair must be tested for proper

operation before being returned to

service. Only parts manufactured by

Emerson should be used for repairing

this valve.

Under normal conditions, complete dismantling

at regular intervals is not recommended. A valve

kept relatively free of dirt will function for years with

minimum attention.

After the first few days of operation and twice a year:

1. Inspect for dirt collected in chamber "C". Remove

plug (key 22) to "blow down".

2. Inspect for dirt collected in cylinder (key 12).

3. Inspect all joints for leakage. Keep all joints tight,

never allow a leak to persist.

7. Remove valve disk assembly which consists of

keys 11, 12, 13, 14, 15 and 18.

8. Assemble in reverse order. Use silicone lubricant

on piston (key 14) so that it will move freely

through sealing ring (key 13).

Type N6

Viton®is a mark owned by E.I. du Pont de Nemours and Co.

*Recommended Spare Parts

1. Top Cap for 1-1/2, 2 and 2-1/2 in. / 38.1, 50.8 and 63.5 mm is Cast iron.

2. Included in Item 23:

Sizes 3/4 to 2 in. / 19.05 to 50.8 mm inclusive are screwed ends

Sizes 2-1/2 in. is 250 lbs / 113 kg

KEY DESCRIPTION MATERIAL VALVE SIZE, IN. / mm

3/4 / 19.05 1 / 25.4 1-1/4 / 31.75 1-1/2 / 38.1 2 / 50.8 2-1/2 / 63.5

1Top Cap(1) Steel WAL4-01303-0 WAL4-01303-0 WAL4-01303-0 WAL4-01331-0 WAL4-01331-0 WAL4-01331-0

2 Adjusting Screw Steel WAL5-04860-0 WAL5-04860-0 WAL5-04860-0 WAL5-04863-0 WAL5-04864-0 WAL5-04864-0

3 Adjusting Screw Locknut Steel WAL5-02942-0 WAL5-02942-0 WAL5-02942-0 WAL5-02943-0 WAL5-02943-0 WAL5-02943-0

4* Top Cap Gasket Copper

Asbestos WAL5-02356-0 WAL5-02356-0 WAL5-02356-0 WAL5-02357-0 WAL5-02357-0 WAL5-02357-0

5 Spring Buttons Steel WAL0-01040-0 WAL0-01040-0 WAL0-01040-0 WAL5-01060-0 WAL5-01050-0 WAL5-01062-0

6 Spring Chamber Cast iron WAL4-01398-0 WAL4-01399-0 WAL4-01400-0 WAL4-01401-0 WAL4-01402-0 WAL4-01403-0

7 Adjusting Spring

5 to 50 psi / 0.35 to 3.45 bar Aluminum

Steel WAL5-04957-0 WAL5-04958-0 WAL5-04959-0 WAL5-04960-0 WAL5-04961-0 WAL5-04962-0

40 to 125 psi / 2.75 to 8.62 bar 17-7 PH WAL5-04972-1 WAL5-04973-1 WAL5-04974-1 WAL5-04975-1 WAL5-04976-1 WAL5-04977-1

100 to 200 psi / 6.89 to 13.79 bar Aluminum

Steel WAL5-10327-0 WAL5-10328-0 WAL5-10329-0 WAL5-10330-0 WAL5-10331-0 WAL5-10332-0

8 Spring Chamber Studs Steel WAL4-05516-0 WAL4-10118-0 WAL4-05442-0 WAL4-05443-0 WAL4-10119-0 WAL4-05447-0

9 Spring Chamber Nuts Steel WAL5-02847-0 WAL5-02851-0 WAL5-02854-0 WAL5-02856-0 WAL5-02860-0 WAL5-02862-0

10* Spring Chamber Gasket Asbestos WAL5-02381-0 WAL5-02362-0 WAL5-02382-0 WAL5-02365-0 WAL5-02366-0 WAL5-02367-0

11 Cylinder Bronze WAL4-01569-1 WAL4-01570-1 WAL4-01571-1 WAL4-01572-1 WAL4-01573-1 WAL4-01574-1

12* Sealing Ring Viton®WAL5-04021-0 WAL5-04026-0 WAL5-10463-0 WAL5-04034-0 WAL5-04044-0 WAL5-04048-0

13 Stem Locknut Steel WAL5-03015-0 WAL5-03016-0 WAL5-03016-0 WAL5-03017-0 WAL5-03017-0 WAL5-03018-0

14 Piston Stainless

steel WAL4-03336-0 WAL4-03337-0 WAL4-03338-0 WAL4-03339-0 WAL4-03340-0 WAL4-03341-0

15 Disk Stainless

steel WAL4-02007-0 WAL4-01832-2 WAL4-01850-2 WAL4-01870-2 WAL4-01888-2 WAL4-01906-1

16 Seat Ring Stainless

steel WAL4-04075-1 WAL4-04084-1 WAL4-04092-1 WAL4-04496-1 WAL4-11544-0 WAL4-11539-0

17 Body(2) Cast iron - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

18 Stem Stainless

steel WAL4-05311-1 WAL4-05312-1 WAL4-05313-1 WAL4-05314-1 WAL4-05315-1 WAL4-05316-2

19 Bushing(2) 17-7 PH WAL4-01094-1 WAL4-01099-2 WAL4-01095-1 WAL4-10630-0 WAL4-10630-0 WAL4-10522-0

20 Body Cap Cast iron WAL4-01300-0 WAL4-01300-0 WAL4-01301-0 WAL4-01301-0 WAL4-01302-0 WAL4-01325-0

21 Pipe Plug, 1/8 NPT Steel WAL4-03769-0 WAL4-03769-0 WAL4-03769-0 WAL4-03769-0 WAL4-03769-0 WAL4-03769-0

22 Piple Plug, 1/4 NPT Steel WAL4-03772-0 WAL4-03772-0 WAL4-03772-0 WAL4-03772-0 WAL4-03772-0 WAL4-03772-0

23 Body and Bushing Cast iron WAL7-42862-1 WAL7-42863-1 WAL7-42864-1 WAL7-42865-1 WAL7-42866-1 WAL7-42867-1

Repair Kit

(4, 10, 11, 12, 13, 14, 15, 16

and 18)

- - - - - - - WAL7-08362-1 WAL7-08363-1 WAL7-08364-1 WAL7-08365-1 WAL7-08366-1 WAL7-08367-1

Parts Ordering

When corresponding with your local Sales Office about this

equipment, always reference the equipment serial number

that can be found on the nameplate.

When ordering replacement parts, reference the key number

of each needed part as found in the following parts list.

Table 3. Type N6 Parts List

Parts List

Type N6

See Table 3

Type N6

1/4 NPT

Figure 3. Type N6 Assembly Drawing

SERIAL NUMBER PLATE

Type N6

Emerson Automation Solutions

SpenceValve.com

Americas

McKinney, Texas 75070 USA

T +1 800 558 5853

+1 972 548 3574

Europe

Bologna 40013, Italy

T +39 051 419 0611

Asia Pacic

Singapore 128461, Singapore

T +65 6777 8211

Middle East and Africa

Dubai, United Arab Emirates

T +971 4 811 8100

SIOI97

Spence is a mark owned by one of the companies in the Emerson Automation

Solutions business unit of Emerson Electric Co. The Emerson logo is a

trademark and service mark of Emerson Electric Co. All other marks are

property of their prospective owners.

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. All sales are

governed by our terms and conditions, which are available upon request. We

reserve the right to modify or improve the designs or specications of such

products at any time without notice.

Emerson Electric Co. does not assume responsibility for the selection, use

or maintenance of any product. Responsibility for proper selection, use

and maintenance of any Emerson Electric Co. product remains solely with

the purchaser.

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