Emerson EZH, EZHSO Instruction Manual

Africa

Instruction Manual NTAEZH0811

November 2008 - Rev. 06

Types EZH and EZHSO

Types EZH and EZHSO Pressure Reducing Regulators

Contents

Introduction ........................................................................ 2

Characteristics ................................................................... 3

Labelling ............................................................................ 5

Dimensions and Weights ................................................... 6

Description ......................................................................... 8

Principle of Operation ......................................................... 8

Monitoring Systems ............................................................ 11

Installation ......................................................................... 13

Startup and Adjustment ..................................................... 15

Shutdown ........................................................................... 16

Maintenance ...................................................................... 17

Troubleshooting ................................................................. 24

Spare Parts ........................................................................ 25

Parts List ............................................................................ 26

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 operated, and maintained in accordance with federal, state, and local codes, rules and regulations, and Emerson Process Management Regulator Technologies, Inc. (Regulator Technologies) instructions.

If the regulator vents gas or a leak develops in the system, service to the unit may be required. Failure to correct trouble could result in a hazardous condition.

Call a gas service person to service the

unit. Only a qualied person must install or

service the regulator.

regulators must be installed,

R94

Figure 1. Type EZH Pressure Reducing Regulator

TYPE PRX-120/APTYPE PRX-120

Figure 2. PRX Series Pressure Reducing Pilots

Types EZH, EZHSO, EZH OS2, and EZHSO OS2

regulators are in conformity with the

Pressure Equipment Directive

PED 97/23/EC and are classied in Category IV.

www.fisherregulators.com

Africa

Types EZH and EZHSO

INTRODUCTION

Scope of Manual

This manual provides installation, startup, maintenance, and parts ordering information for the Types EZH and EZHSO pressure-reducing regulators and Type PRX pilot

with Type SA/2 pilot supply lter regulator.

Information on other equipment used with this regulator is found in separate manuals.

Product Description

Types EZH and EZHSO regulators are accurate pilotoperated pressure balanced, soft-seated regulators. They are designed for use in high pressure natural gas transmission/city gate stations, large capacity distribution systems, and power plant feeds. They provide smooth, reliable operation, tight shutoff, and long life.

Type EZHSO "Spring-to-Open" version could be used when other overpressure protection options are foreseen,

for example in a monitor conguration. In this case, in

event of failure, the main regulator will stay completely open, allowing the monitor to take control. The monitor could be "Spring-to-Close" to ensure a double protection to downstream pipe.

Available Congurations:

• Type PRX/120:

Outlet pressure range of 1 to 40 bar. The T ype PRX/120 can be used as the pilot on single stage pressure reducing regulators, as the monitor pilot, or as the working pilot in wide-open monitor systems.

• Type PRX/120-AP: Outlet pressure range of 30 to 80 bar . The Type PRX/120-AP

can be used as the pilot on single stage pressure reducing regulators, as the monitor pilot, or as the working pilot in wide-open monitor systems.

• Type PRX/125: Identical to the Type PRX/120, except the restriction screw

is removed. The Type PRX/125 can only be used as the monitor override pilot on working monitor applications.

• Type PRX/125-AP: Identical to the Type PRX/120-AP, except the restriction

screw is removed. The Type PRX/125-AP can only be used as the monitor override pilot on working monitor applications.

• Type SA/2 Pilot Supply Filter Regulator:

The Type SA/2 pilot supply lter regulator provides a

constant pressure supply to the PRX Series pilot of 3 bar over the set pressure. The Type SA/2 has an integral

5-micron lter. For easy maintenance a block valve can

be installed to separate the regulator from the pilot.

• Types EZH and EZHSO ("E Body")

Single regulator without slam shut

• Types EZH and EZHSO ("X Body")

Single regulator in a X Body

In case of modication made on a pressure equipment

like cap replacement by a slam shut it's mandatory to comply to the local codes, rules and regulations. Contact us imperatively.

• Types EZH OS2 and EZHSO OS2 ("X Body")

Single regulator with integrated slam shut

Pilot Description

Type PRX Pilot

The Types EZH and EZHSO pressure-reducing regulators can be equipped with a PRX Series pilot mounted on the main valve for pressure reducing or wide-open monitoring applications. The PRX Series pressure reducing pilots have the ability to handle a wide range of setpoints from 1 to 80 bar:

Regulator Options

• Silencer (Figure 22)

The Type EZH silencer (Whisper III) is integrated in the regulator and is composed of a drilled cage. The Whisper III silencer is available for DN 25, 50, 80, and 100 and allows a noise attenuation up to 8dB.

• Flow Coefcient Reduction (Figure 16)

The ow reduction is realised by replacement of the

regulator standard seat by a reduction seat ( key 2).

• Type RPE Electrical Pilot Heater (Figure 25)

The Type RPE is used for reheating the gas supplying pressure reducing regulator pilots. The Type RPE avoids the inconveniences caused by freezing which can occur during high pressure drops.

Actuator

The actuator is an integral pressure type. All pressure parts are designed to resist up to 100 bar. The diaphragm is strong and can resist to a differential of 100 bar.

Africa

CHARACTERISTICS

Table 1. General Characteristics for Types EZH and EZHSO Regulator

OPERATING PRESSURE

A352LCC Body, Actuator, Valve, Pilot Body, Slam shut

Associated BMS Type IS Integral strength

OPERATING TEMPERATURE

Sizes available DN 25, 50, 80, and 100 Noise level reduction Up to 8 dB

REGULATOR

European EN Standard EN 334 Inlet Pressure Pu 2 to 100 bar Outlet Pressure Pd 1 to 80 bar

Minimum Differential DP min

Maximum Differential DP max Accuracy (optimal) AC See Table 2

Lock-Up Pressure Class SG Up to 5% Lock-Up Pressure Zone Class SZ Up to 5%

(1) BMS - Safety Manometric Box (2) Standard version

(1)

, according to size PSD 10 to 100 bar

(2)

PS 100 bar max

TS -20 / 60°C Class 2

1 bar (Type EZH)

3.8 bar (Type EZHSO) 99 bar (Type EZH)

96.2 bar (Type EZHSO)

(3)

(3) Contact us with your operating conditions

(4) Depending on BMS conguration for Type EZH OS2

Types EZH and EZHSO

SLAM SHUT

European EN Standard EN 14382 Operation Class

(4)

Maximum Operating Differential DP max 100 bar Response Time ta <1 s

Diaphragm,

Accuracy

Set Pressure Range

Flow Coefcient Q

Internal Automatic Bypass C Rearming Manual after rectication of fault Position Indicator On mechanism box

Groups 1 and 2 according to PED 97/23/EC, Gas 1

Bellows Piston Up to ±5%

Wdu-Wdo

Fluid

EN 437, or other gases (compressed air, nitrogen).

The gas must be non corrosive, clean

(ltration on inlet side necessary) and dry.

A or B (see Figure 3)

Up to ±2.5%

0.010 / 100 bar 13

and 2nd family according to

Table 2. Outlet Pressure Ranges, Accuracy Class, and Pilot Spring Information

TYPE

PRX/120 and

PRX/125

PRX/120-AP and

PRX/125-AP

OUTLET PRESSURE

ADJUSTMENT RANGES (bar)

1.0 to 1.8

1.8 to 3.0

3.0 to 5.5

5.5 to 8.5

8.5 to 14.5

14.5 to 23.0

23.0 to 30.0

30.0 to 40.0

30.0 to 80.0 1% 2.5% Clear

AC (ACCURACY CLASS) PILOT CONTROL SPRING INFORMATION

TYPE EZH TYPE EZHSO Spring Colour

2.5%

2.5% 1%

1% 1% 1%

2.5%

Yellow Green

Blue

Black Silver

Gold

Aluminium

Red

Table 3a. 2:1 Line Flow Coefcients, Regulator, and Slam-Shut Travel

TYPES EZH (DN 25 - 100) AND EZHSO (DN 25 - 100)

REDUCTION

1 2 3 0

1 2 3

284 1078 2247 3567 280 1088 2266 3696 210 908 1684 2969 218 829 1698 2902 126 671 1058 1763 128 607 1066 1784

79 385 685 1062 81 370 690 1072 550 2092 4359 6920 544 2110 4396 7170 408 1762 3266 5760 423 1609 3294 5630 245 1301 2052 3420 249 1177 2069 3460 154 746 1328 2060 157 718 1339 2080

31.3 38.3 30.8 32.5 35.5 33.5 30.8 31.4

34.3 35.3 33.9 35.3 38.7 31.9 33.9 34.2

33.6 38.8 37.8 37.3 39.7 35.6 37.8 36.3

32.1 40.8 33.6 37.1 39.1 38.2 33.6 37.3 Regulator travel (mm) 9 17 25 30 9 17 25 30 Slam-shut travel (mm) 15 30 50

WITH SLAM SHUT (X BODY) WITHOUT SLAM SHUT (E BODY)

25 DN 50 DN 80 DN 100 DN 25 DN 50 DN 80 DN 100

R95

R96

Africa

Types EZH and EZHSO

Table 3b. 2:1 Line Flow Coefcients, Regulator with Integrated Whisper III Silencer

TYPES EZH (DN 25 - 100) WITH WHISPER III AND EZHSO (DN 25 - 100) WITH WHISPER III

REDUCTION

1 2 3 0 1 2 3 0 1 2 3

SLAM SHUT INTEGRATED (X BODY) WITHOUT SLAM SHUT (E BODY)

25 DN 50 DN 80 DN 100 DN 25 DN 50 DN 80 DN 100

223 781 1693 2742 255 793 1708 2789 215 764 1418 2479 209 716 1172 2438 140 603 975 1644 127 566 984 1711

87 370 685 1041 81 358 690 1057 433 1516 3285 5320 495 1539 3313 5410 417 1482 2751 4810 406 1389 2774 4730 273 1169 1892 3190 247 1099 1908 3320 168 718 1328 2020 158 695 1339 2050

35.5 37 30.8 31.7 33.8 33.5 30.8 30.4

35.4 37.5 33.6 34.1 39.4 34.1 33.6 32.4

32.3 39.5 37.1 36.4 39.9 35.7 37.1 35.7

32.9 39.4 38.3 37.6 39.9 37.7 38.3 37.3

PART NAME

Filter

Pilot Disk Pilot cannot be closed

Pilot Lower Diaphragm

Pilot Upper Diaphragm

Regulator

Diaphragm

Pilot

FAILURE

(WORST CASE)

Filter blocked/

clogged

Pilot cannot control

Pilot cannot feed

the regulator

Not proper

performance of

the motorization

pressure chamber

Frozen Pilot,

Type SA/2 working

Table 4. Failure Mode Analysis

CAUSE OF

FAILURE

Debris or aromatics

present in the gas

Debris or aromatics

present in the gas

Debris or aromatics

present in the gas

Debris or aromatics

present in the gas

Debris or aromatics

present in the gas

Moisture in the gas,

high pressure drop

EFFECT REGULATOR TYPE REGULATOR REACTION MODE

Decrease of feeding

pressure gives

decrease of

motorization pressure

Increase

motorization

pressure

Decrease

motorization

pressure

Decrease

motorization

pressure

Balancing of

pressures and charge

or discharge of

the motorization

pressure chamber

Type SA/2 loading

upper casing of

regulator, Pilot

not supplying

loading pressure

to lower casing

EZHSO Open ---

EZH --- Close

EZHSO Open ---

EZH Open ---

EZHSO Open ---

EZH --- Close

EZHSO Open ---

EZH --- Close

EZHSO Open ---

EZH --- Close

EZHSO --- Close

EZH --- Close

R96B

Africa

Types EZH and EZHSO

Connections

Inlet/Outlet : CL150 RF - CL300 RF - CL600 RF PN 16B - PN 25B - PN 40B Other congurations available

(contact factory)

Pilot feed: 1/4’’ NPT female Pilot Reject: 1/4’’ NPT female Pilot impulse: 1/4’’ NPT female Slam-shut impulse: 1/4’’ NPT female BM* vent: 1/4’’ NPT female Impulse tube diameter: Interior Ø 8/10 mm Contact switch: See NTAOS2

* BM - Mechanism Box

LABELLING

OS2 -

EZH EZHSO

REGULATEUR/REGULATOR

SECURITE/SLAM SHUT

GROUPE

série

N°

serial

(Gaz Naturel)

CatPS

Date Fab/Test Mfg/Testdate

Standard EN14382 -

norme standard norme standard

bar

DD MM YEAR

Figure 3. Types EZH OS2 and EZHSO OS2 Label (X Body)

matériau shell

Material

Body: Steel Connecting parts and bottom: Steel Actuator: Steel

Regulator/Slam-shut orice: Stainless steel

Regulator valve plug: Stainless steel Slam-shut valve plug: Stainless steel Regulator plug disc/

Slam-shut O-rings: Nitrile (NBR) or

Fluorocarbon (FKM)

BMS Setting

BMS 027/017 BMS162

Max only

BMS 236/315 BMS071 Min onlyAll Max-Min types of BMS

Failure mode FC

EN 334

bar

A352LCC+A350LF2

SecurityClass

mode défaillance failure mode classe sécurité slam shut class

Temp TS

-20/+60°C

Pumax 18.9

PT PS

DN 25 50 80 100

CL150 RF CL300 RF CL600 RF

DN Pumax bar

Class Type Cg

Reduction 0123

IS DS

CLASS

150 300 600

16B 25B

5050100

32 79 158

18.9 100

PN16B PN25B PN40B

Otherconfigurations available (contactfactory)

28320 Gallardon-France

FISHER

FRANCEL

0062

Cg See Table3

Depending on BMS configuration

40B

25 26 40 16

40 63

Failure mode FC FO

DN 25 50 80 100

N°

GROUPE

(Gaz Naturel)

CL150 RF CL300 RF CL600 RF

PN16B PN25B PN40B

mode défaillance failure mode

série serial

REGULATEUR/ REGULATOR

Temp TS

matériau shell

Cat

Type

Date Fab/Test Mfg/Testdate

bar

-20/+60°C A352LCC+A350LF2

FISHER

Other configurations available (contact factory)

norme

EN 334

standard

bar

Pumax bar

Class

FRANCEL

28320 Gallardon-France

EZH

0062

Figure 4. Types EZH and EZHSO Label (E Body)

EZHSO

Reduction0123

Cg See table3

DD MM YEAR

Date

CLASS

150 300 600

Pumax 18.9

PT PS

5050100

32 79 158

18.9 100

16B 25B

16 26 40 16

40B

40 63

R97

Africa

Types EZH and EZHSO

HIE

25 mm Mechanism box removal clearance

DIMENSIONS AND WEIGHTS

DN 25, 50, and 80 DN 100

Indicator cover

removal clearance

Indicator cover

removal clearance

25 mm Mechanism box removal clearance

R112a

Figure 5. Dimensions — Types EZH OS2 and EZHSO OS2

DN 25, 50, 80, and 100

I HE

25 mm Mechanism box removal clearance

Figure 6. Dimensions — Types EZH OS2 and EZHSO OS2

(Vertical Position)

(Horizontal Position)

For Type EZHSO OS2 version add 1 kg

Table 6a. Dimensions — Types EZH OS2 and EZHSO OS2

25 50 80

100

Table 5. Approximate Regulator Weights

Types EZH OS2 and EZHSO OS2

CL150/PN 16B CL300/PN 25B/PN 40B CL600

25 49 50 51 50 81 83 85 80 168 175 177

100 237 250 265

OVERALL DIMENSIONS (mm)

F G

Diaphragm Piston Bellows Diaphragm Piston Bellows

181 204 223 162 71 74

WEIGHTS (kg)

R113a

Table 6b. Dimensions — Types EZH OS2 and EZHSO OS2

MAXIMUM OVERALL DIMENSIONS (mm)

CL150 CL300 CL600 PN 16B PN 25B PN 40B

Type PRX

Horizontal

25 184 197 210 193.5 250 290 310 315 320 260 250 113 280 190 50 254 267 286 254 267 265 320 320 330 380 310 310 144 270 190 80 298 317 337 310 317 301 400 400 366 500 390 390 200 270 270

100 352 368 394 350 368 345 442 427 410 580 394 394 240 140

Type PRX

Vertical

D E

Type PRX

Horizontal

Type PRX

Vertical

Type PRX

Horizontal

Type PRX

Vertical

R114a

Africa

Indicator cover removal clearance

Indicator cover

Indicator cover removal clearance

JIH

Indicator cover removal clearance

removal clearance

DN 25, 50, and 80

JIH

Types EZH and EZHSO

(1)

DN 100

Indicator cover

removal clearance

R115a

Figure 7. Dimensions — Types EZH and EZHSO

(Horizontal Position)

DN 25, 50, 80, and 100

25 38 39 40 50 71 74 75 80 145 151 153

100 211 224 239

(1) For Type EZHSO version add 1 kg

Table 7. Approximate Regulator Weights

Types EZH and EZHSO

(1)

WEIGHTS (kg)

CL150/PN 16B CL300/PN 25B/PN 40B CL600

R116a

Figure 8. Dimensions — Types EZH and EZHSO

(Vertical Position)

Table 8. Dimensions — Types EZH and EZHSO

CL150 CL300 CL600 PN 16B PN 25B PN 40B

25 184 197 210 193.5 62 290 310 320 260 250 113 280 190 50 254 267 286 254 267 83 320 320 380 310 310 144 270 190 80 298 317 337 310 317 105 400 400 500 390 390 200 270 270

100 352 368 394 350 368 137 442 427 580 394 394 240 140

MAXIMUM OVERALL DIMENSIONS (mm)

Type PRX

Horizontal

Type PRX

Vertical

Type PRX

Horizontal

Type PRX

Vertical

Type PRX

Horizontal

Type PRX

Vertical

R117a

Africa

Types EZH and EZHSO

TYPE

FILTER

SA/2

TYPE PRX/120

UPPER DIAPHRAGM

PILOT DISK

Inlet pressure (Pu) Motorization pressure (Pm) Pilot feeding pressure (Pup) Outlet pressure (Pd) Atmospheric pressure (Pb)

DESCRIPTION

REGULATOR DIAPHRAGM

TYPE EZH

TYPE PRX:

S - BLEED PORT TYPE SA/2 B - SUPPLY PORT V - SENSING L - MOTORIZATION PORT R - PILOT A - SENSING PORT M - INLET

Figure 9. Type EZH DN 25/50/80 (Spring-to-Close Version) Operational Schematic

PRINCIPLE OF OPERATION

LOWER DIAPHRAGM

R98

The Types EZH and EZHSO regulators consist of:

• Version without Integral Slam-Shut Valve:

- An "E Body" or an "X Body plus a cap"

- A compensation valve, an interchangeable orice

- An actuator with position indicator

- A pilot system adapted to the required pressure setpoint

• Version with Integral Slam-Shut Valve:

- Same parts and sub-assemblies as in the version without slam shut

- An "X Body"

- A valve with tight shut-off O-ring

- An automatic slam-shut bypass

- A release relay Type OS2 (see instruction manual NTAOS2) consisting of:

· A mechanism box (BM)

· A safety manometric box (BMS) connected to the outlet side of the regulator

Type EZH — Spring-to-Close Version

Type EZH Single-Pilot Regulator (Figures 9 and 10)

The pilot-operated Type EZH uses inlet pressure as the operating medium, which is reduced through pilot operation to load the actuator diaphragm. Outlet pressure (Pd) opposes the motorization pressure (Pm) in the actuator and also opposes the pilot control spring.

When the outlet pressure (Pd) drops below the setting of the pilot control spring, pilot control spring force on the pilot diaphragm thus opens the pilot valve plug, providing additional motorization pressure (Pm) to the actuator diaphragm. This diaphragm motorization pressure opens

the main valve plug, supplying the required ow to the

downstream system. Any excess motorization pressure on the actuator diaphragm

escapes downstream through the bleed restriction in the pilot.

Africa

Types EZH and EZHSO

RP IP

Inlet pressure (Pu) Motorization pressure (Pm) Pilot feeding pressure (Pup) Outlet pressure (Pd) Atmospheric pressure (Pb)

TYPE PRX:

S - BLEED PORT TYPE SA/2 B - SUPPLY PORT V - SENSING L - MOTORIZATION PORT R - PILOT A - SENSING PORT M - INLET

Figure 10. Type EZH-OS2 DN 100 (Spring-to-Close Version) Operational Schematic

When the gas demand in the downstream system has

been satised, the outlet pressure (Pd) increases. The

increased pressure is transmitted through the downstream control line and acts on the pilot diaphragm. This pressure exceeds the pilot spring setting and moves the Type PRX

diaphragm, closing the Type PRX orice and interrupting

the motorization pressure supply to main valve actuator. The excess of motorization pressure (Pm) acting on both

the main diaphragm and Type PRX pilot bleeds to the downstream system through a bleed restriction in the pilot.

For Type EZH DN 100 a check valve (Figure 26) is installed

between outlet pressure and motorization pressure impulse lines; this valve will protect the diaphragm assembly from wrong procedures during startup, avoiding a too high pressure differential between outlet and motorization pressure.

Type EZHSO — Spring-to-Open Version

Type EZHSO Single-Pilot Regulator (Figures 11 and 12)

CAUTION

The pilot-operated Type EZHSO (Spring-toOpen version) will fail in open position in case of main valve diaphragm failure or lack of pressure supply to the pilot (see Table 4 for Failure Mode Analysis).

Africa

Types EZH and EZHSO

UPPER DIAPHRAGM

FILTER

Inlet pressure (Pu) Motorization pressure (Pm) Pilot feeding pressure (Pup) Outlet pressure (Pd) Atmospheric pressure (Pb)

TYPE SA/2

TYPE PRX:

S - BLEED PORT TYPE SA/2 B - SUPPLY PORT V - SENSING L - MOTORIZATION PORT R - PILOT A - SENSING PORT M - INLET

LOWER DIAPHRAGM

TYPE PRX/120

PILOT DISK

TYPE EZHSO

REGULATOR DIAPHRAGM

Figure 11. Type EZHSO DN 25/50/80 (Spring-to-Open Version) Operational Schematic

Type EZHSO uses inlet pressure as the operating medium, which is reduced through pilot operation to load the actuator diaphragm (lower chamber). The upper case of

Type EZHSO actuator is lled with pressure coming from

pre-regulator Type SA/2, which reduces inlet pressure (Pu) to the constant value of outlet pressure plus approximately 3 bar. This pressure opposes the main spring force that tends to open the regulator. Outlet or downstream pressure (Pd) opposes the pilot control spring. When outlet pressure drops below the setting of the pilot control spring, pilot control spring force on the pilot diaphragm opens the pilot valve plug, providing additional motorization pressure (Pm) to the actuator diaphragm.

This diaphragm motorization pressure opens the main valve

plug, supplying the required ow to the downstream system.

Any excess motorization pressure on the actuator diaphragm escapes downstream through the bleed restriction in the pilot.

When outlet pressure increases over the setting of the pilot spring, the pilot valve plug will be closed reducing motorization pressure to the actuator diaphragm; the pressure in the upper case will force the regulator to close.

For Type EZHSO DN 100 a check valve (Figure 26) is

installed between outlet pressure and loading pressure

impulse lines; this valve will protect the diaphragm assembly from wrong procedures during startup, avoiding a too high pressure differential between outlet and motorization pressure.

EZH and EZHSO Series Adjustment

The adjustment of the regulator is performed by means of the pilot adjusting screw, which causes variation of the compression of the control spring.

Adjustment is performed while the regulator is in operation with the aid of a pressure gauge to monitor downstream pressure.

The shut-off valve downstream of the regulator must not be completely closed, it is necessary that a small quantity of

gas ows downstream to allow the outlet side to vent when it

is necessary to lower the pressure. Loosen the Type PRX pilot locknut and turn the adjusting

screw slowly clockwise to increase outlet pressure and counterclockwise to decrease outlet pressure. Use a pressure gauge to monitor the outlet pressure until the desired pressure is reached. No adjustment is needed to

the Type SA/2 stabilizer lter.

Africa

Types EZH and EZHSO

Inlet pressure (Pu) Motorization pressure (Pm) Pilot feeding pressure (Pup) Outlet pressure (Pd) Atmospheric pressure (Pb)

TYPE PRX:

S - BLEED PORT TYPE SA/2 B - SUPPLY PORT V - SENSING L - MOTORIZATION PORT R - PILOT A - SENSING PORT M - INLET

RP IP

Figure 12. Type EZHSO DN 100 (Spring-to-Open Version) Operational Schematic

MONITORING SYSTEMS

Monitoring regulation is overpressure protection by containment, therefore, there is no relief valve to vent to the atmosphere. When the working regulator fails to control the pressure, a monitor regulator installed in series, which has been sensing the downstream and control pressure, goes into operation to maintain the downstream pressure at a slightly higher level than normal pressure. During an overpressure situation, the monitoring system keeps the customer on line.

Also testing is relatively easy and safe. To perform a periodic test on a monitoring regulator, increase the outlet set pressure of the working regulator and watch the outlet pressure to determine if the monitoring regulator takes over at the appropriate outlet pressure.

Wide-Open Monitoring Systems

In normal operation of a wide-open conguration, the

working regulator controls the system’s outlet pressure. With a higher outlet pressure setting, the monitor regulator senses a pressure lower than its setpoint and tries to increase outlet pressure by going wide open. If the working regulator fails, the monitoring regulator assumes control and holds the outlet pressure at its outlet pressure setting.

Figure 13 shows an upstream wide-open monitor Type EZH

(Spring-to-Close) and a downstream active regulator

Type EZHSO (Spring-to-Open). With this conguration,

in case of regulator main diaphragm failure, it will fail in open position letting the monitor work properly; in case of monitor main diaphragm failure, it will fail in close position guaranteeing a protection against overpressure to downstream system.

+ 25 hidden pages

Emerson EZH, EZHSO Instruction Manual

Specifications and Main Features

Frequently Asked Questions

User Manual