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 www.SpenceValve.com

 www.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 Differential 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

Summary of Contents for Spence Type N6

Page 1: ... 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 pressur...

Page 2: ...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 Differential Pressure Valve Rated Flow Coefficients BODY SIZE FL...

Page 3: ...he 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 dru...

Page 4: ...re 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 ...

Page 5: ...ign 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...

Page 6: ...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...

Page 7: ...1 2 3 4 23 24 25 5 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 1 4 NPT Figure 3 Type N6 Assembly Drawing SERIAL NUMBER PLATE 7 Type N6 ...

Page 8: ...re property of their prospective owners The contents of this publication are presented for informational purposes only and while every effort 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 ...

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