Emerson MR98L, MR98H Instruction Manual

Instruction Manual
D103588X012

January 2021

MR98 Series

MR98 Series Backpressure Regulators, Relief

and Di󰀨erential Relief Valves

P1757_1

TYPE MR98L

P1753_1

TYPE MR98H

Figure 1. Typical MR98 Series Backpressure Regulators, Relief and Differential Relief Valves

MR98 Series

Specications

This section lists the specications for the MR98 Series regulators. Factory specication such as type, maximum
inlet pressure, maximum temperature, maximum outlet pressure, spring range, orice size and seat material are
stamped on the nameplate fastened on the regulator at the factory.

Available Constructions

Type MR98L: Backpressure regulator/relief
valve for spring settings range from 2 to 38 psig /

0.14 to 2.6 bar, available for 1/4 NPT to NPS 1 /
DN 25 body sizes only.
Type MR98H: Backpressure regulator/relief valve
for spring settings range from 5 to 200 psig /

0.34 to 13.8 bar.
Type MR98HH: Backpressure regulator/relief
valve for spring settings range from 150 to
375 psig /10.3 to 25.9 bar.
Type MR98LD: Di󰀨erential pressure relief valve
for di󰀨erential set pressures range from 2 to
38 psi / 0.14 to 2.6 bar with maximum inlet/outlet
pressure up to 150 psi / 10.3 bar, available for
1/4 NPT to NPS 1 / DN 25 body sizes only.
Type MR98HD: Di󰀨erential pressure relief valve
for di󰀨erential set pressures from 5 to 200 psi /

0.34 to 13.8 bar with maximum inlet / outlet
pressure up to 300 psi / 20.7 bar.
Type MR98HDP: Di󰀨erential pressure relief valve
for di󰀨erential set pressures range from 5 to
200 psi / 0.34 to 13.8 bar with maximum inlet/
outlet pressure up to 600 psi / 41.4 bar.
Type MR98HHD: Di󰀨erential pressure relief valve
for di󰀨erential set pressures range from 150 to
375 psi / 10.3 to 25.9 bar with maximum inlet/
outlet pressure up to 400 psi / 27.6 bar.

Body and Orice Sizes

1/4 NPT: 0.284 in. / 7.22 mm
NPS 1/2 / DN 15: 0.416 in. / 10.56 mm
NPS 3/4 and 1 / DN 20 and 25:

0.631 in. / 16.02 mm

NPS 1-1/2 and 2 / DN 40 and 50:

1.142 in. / 29 mm

Body End Connections

See Tables 1 and 2

Set Pressure Ranges

(1)

See Table 3

Maximum Cold Working Pressures of Body Size

and Materials

(1)

See Table 4

Maximum Temperature Ranges of Diaphragm, Seat,
Trim and Body Materials

(1)(2)(3)

See Table 5

Flow Coe󰀩cients

BODY SIZE

NPS DN

1/4 NPT - - - - 1.4 48 34.3

1/2 15 3.4 120 35.3

3/4 and 1 20 and 25 6.5 250 38.5

1-1/2 and 2 40 and 50 20.0 780 39.0

C

v

C

g

C

1

IEC Sizing Coe󰀩cients

BODY SIZE

NPS DN

1/4 NPT - - - - 0.743 0.74 0.95 0.90

1/2 15 0.787 0.78 0.94 0.88

3/4 and 1 20 and 25 0.935 0.70 0.91 0.83

1-1/2 and 2 40 and 50 0.961 0.69 0.94 0.88

X

T

F

d

F

L

K

m

Pressure Registration

Internal or External

Shuto󰀨 Classication Per ANSI/FCI 70-3-2004

Metal Seats: Class IV

Polytetrauoroethylene (PTFE): Class IV

Elastomer Seats: Class VI or better

Sour Gas Service Capability

Optional materials are available for applications
handling sour gases. These constructions comply
with the recommendations of NACE International
Standards MR0175-2002, NACE MR0103 and/or
NACE MR0175/ISO 15156.

API 614 Compliant

Steel or Stainless steel constructions with
Stainless steel trim meet API 614 Requirements.

Approximate Weights

MR98H Series:

1/4 NPT: 5 lbs / 2.3 kg
NPS 1/2 / DN 15: 10 lbs / 4.5 kg
NPS 3/4 and 1 / DN 20 and 25: 22 lbs / 10 kg
NPS 1-1/2 and 2 / DN 40 and 50: 55 lbs / 25 kg

MR98L Series:

1/4 NPT: 7 lbs / 3.2 kg
NPS 1/2 / DN 15: 15 lbs / 6.8 kg
NPS 3/4 and 1 / DN 20 and 25: 35 lbs / 16 kg

Maximum Inlet, Outlet and Spring Case

Pressure Ratings

(1)

See Table 4

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

2. Pressure and/or the body end connection may decrease the maximum temperatures.

3. Special low temperature constructions for process temperatures between -76 to 104°F / -60 to 40°C are available by request. The low temperature construction passed Emerson Process
Management Regulator Technologies, Inc. (Emerson) laboratory testing for lockup and external leakage down to -76°F / -60°C.

2

Table 1. Types MR98L and MR98LD Regulators Body Constructions

BODY SIZE BODY CONSTRUCTION END CONNECTION STYLE

1/4 NPT Without Control Line and Gauge Port NPT

NPS 1/2 / DN 15

NPS 3/4 / DN 20

NPS 1 / DN 25

- Shaded areas indicate that the construction is available.

- Blank areas indicate that you need to contact your local Sales O󰀩ce for the availability of the constructions.

1. Meets the chemical and physical requirements of NACE MR0175-2002, NACE MR0103 and NACE MR0175/ISO 15156.

Without Control Line and Gauge Port

Welded PN 16/25/40 RF

With Control Line but Without Gauge Port NPT

Without Control Line and Gauge Port

Welded PN 16/25/40 RF

With Control Line but Without Gauge Port NPT

With Gauge Port but Without Control Line

Welded PN 16/25/40 RF

Without Control Line and Gauge Port

Welded PN 16/25/40 RF

With Control Line but Without Gauge Port NPT

With Gauge Port but Without Control Line

Welded PN 16/25/40 RF

NPT

SWE

Welded CL150 RF

Welded CL300 RF

NPT

SWE

Welded CL150 RF

Welded CL300 RF

NPT

Welded CL150 RF

Welded CL300 RF

NPT

SWE

Welded CL150 RF

Welded CL300 RF

NPT

Welded CL150 RF

Welded CL300 RF

MR98 Series

BODY MATERIAL

(1)

(1)

(1)

Gray Cast Iron

WCC or LCC Steel

CF8M Stainless steel

CF3M Stainless steel

(1)

C

®

Hastelloy
or

®

Monel

Monel® is a mark owned by Special Metals Corporation.
Hastelloy® C is a mark owned by Haynes International, Inc.

3

MR98 Series

Table 2. Types MR98H, MR98HD, MR98HH, MR98HDP and MR98HHD Regulators Body Constructions

BODY SIZE BODY CONSTRUCTION END CONNECTION STYLE

1/4 NPT Without Control Line and Gauge Port NPT

Without Control Line and Gauge Port

NPS 1/2 / DN 15

With Control Line but Without Gauge Port

Without Control Line and Gauge Port

NPS 3/4 / DN 20

With Control Line but Without Gauge Port

With Gauge Port but Without Control Line

Without Control Line and Gauge Port

NPS 1 / DN 25

With Control Line but Without Gauge Port

With Gauge Port but Without Control Line

- Shaded areas indicate that the construction is available.

- Blank areas indicate that you need to contact your local Sales O󰀩ce for the availability of the constructions.

1. Meets the chemical and physical requirements of NACE MR0175-2002, NACE MR0103 and NACE MR0175/ISO 15156.

2. Available for Types MR98H and MR98HD only.

Welded PN 16/25/40 RF

Integral PN 16/25/40 RF

Welded PN 16/25/40 RF

Welded PN 16/25/40 RF

Welded PN 16/25/40 RF

Integral PN 16/25/40 RF

Welded PN 16/25/40 RF

NPT

SWE

Welded CL150 RF

Welded CL300 RF

Integral CL150 RF

Integral CL300 RF

NPT

Welded CL150RF

Welded CL300RF

NPT

SWE

Welded CL150 RF

Welded CL300 RF

NPT

Welded CL150 RF

Welded CL300 RF

NPT

Welded CL150 RF

Welded CL300 RF

NPT

SWE

Welded CL150 RF

Welded CL300 RF

Integral CL150 RF

Integral CL300 RF

NPT

Welded CL150 RF

Welded CL300 RF

NPT

Welded CL150 RF

Welded CL300 RF

BODY MATERIAL

(1)

(1)

(1)

(2)

Gray Cast Iron

WCC or LCC Steel

CF8M Stainless steel

(1)

C

®

or Hastelloy

®

CF3MStainless steel

Aluminum-Bronze

Monel

Monel® is a mark owned by Special Metals Corporation.
Hastelloy® C is a mark owned by Haynes International, Inc.

4

- continued -

MR98 Series

Table 2. Types MR98H, MR98HD, MR98HH, MR98HDP and MR98HHD Regulators Body Constructions (continued)

BODY SIZE BODY CONSTRUCTION END CONNECTION STYLE

NPT

SWE

Without Control Line and Gauge Port

NPS 1-1/2 / DN 40

Types MR98H and MR98HD only

With Control Line but Without Gauge Port

With Gauge Port but Without Control Line

Without Control Line and Gauge Port

NPS 2 / DN 50

Types MR98H and MR98HD only

With Control Line but Without Gauge Port

With Gauge Port but Without Control Line

- Shaded areas indicate that the construction is available.

- Blank areas indicate that you need to contact your local Sales O󰀩ce for the availability of the constructions.

1. Meets the chemical and physical requirements of NACE MR0175-2002, NACE MR0103 and NACE MR0175/ISO 15156.

Welded CL150 RF

Welded CL300 RF

Welded PN 16/25/40 RF

NPT

Welded CL150 RF

Welded CL300 RF

NPT

Welded CL150 RF

Welded CL300 RF

Welded PN 16/25/40 RF

NPT

SWE

Welded CL150RF

Welded CL300RF

Welded PN 16/25/40 RF

Integral CL150 RF

Integral CL300 RF

Integral PN 16/25/40 RF

NPT

Welded CL150 RF

Welded CL300 RF

NPT

Welded CL150 RF

Welded CL300 RF

Welded PN 16/25/40 RF

BODY MATERIAL

(1)

(1)

(1)

Gray Cast Iron

WCC or LCC Steel

CF8M Stainless steel

CF3M Stainless steel

(1)

C

®

Hastelloy
or

®

Aluminum-Bronze

Monel

®

Monel

is a mark owned by Special Metals Corporation.

Hastelloy® C is a mark owned by Haynes International, Inc.

5

MR98 Series

Table 3. MR98 Series Body Sizes, Pressure Ranges and Spring Information

TYPE

BODY SIZE

CONTROL

PRESSURE RANGE

NPS DN psig bar In. mm In. mm

2 to 7 0.14 to 0.48 0.148 3.76 2.00 50.8 Zinc-plated steel 1E392527022 Yellow

1/4 NPT - - - -

6 to 14 0.41 to 0.97 0.170 4.32 2.00 50.8 Zinc-plated steel ERAA01888A0 Green

12 to 25 0.83 to 1.7 0.207 5.26 1.938 49.2 Powder-coated steel ERAA01889A0 Red

20 to 38 1.4 to 2.6 0.225 5.72 2.086 53.0 Powder-coated steel ERAA01929A0 Blue

2 to 7 0.14 to 0.48 0.207 5.26 2.50 63.5 Powder-coated steel

6 to 14 0.41 to 0.97 0.234 5.94 2.595 65.9 Powder-coated steel

12 to 25 0.83 to 1.7 0.283 7.19 2.44 62.0 Powder-coated steel

20 to 38 1.4 to 2.6 0.331 8.41 2.250 57.2 Powder-coated steel

2 to 7 0.14 to 0.48 0.306 7.77 4.00 102 Powder-coated steel

6 to 14 0.41 to 0.97 0.343 8.71 4.00 102 Powder-coated steel

25

12 to 25 0.83 to 1.7 0.406 10.3 4.00 102 Powder-coated steel

MR98L

and

MR98LD

1/2 15

3/4

and 1

20 and

20 to 38 1.4 to 2.6 0.468 11.9 3.75 95.3 Powder-coated steel 1L380127082 Blue

2 to 7 0.14 to 0.48 0.306 7.77 4.00 102 Powder-coated Stainless steel 1E3989X0052 Yellow

3/4

and 1

20 and

6 to 14 0.41 to 0.97 0.375 9.53 3.88 98.6 Stainless steel 1K762537022 Unpainted

25

12 to 25 0.83 to 1.7 0.437 11.1 4.00 102 Stainless steel 11A8269X012 Unpainted

15 to 35 1.0 to 2.4 0.148 3.76 2.00 50.8 Zinc-plated steel 1E392527022 Yellow

1/4 NPT - - - -

25 to 75 1.7 to 5.2 0.170 4.32 2.00 50.8 Zinc-plated steel ERAA01888A0 Green

70 to 140 4.8 to 9.7 0.207 5.26 1.938 49.2 Powder-coated steel ERAA01889A0 Red

130 to 200 9.0 to 13.8 0.225 5.72 2.086 53.0 Powder-coated steel ERAA01929A0 Blue

15 to 35 1.0 to 2.4 0.207 5.26 2.50 63.5 Powder-coated steel

1/2 15

25 to 75 1.7 to 5.2 0.234 5.94 2.595 65.9 Powder-coated steel

70 to 140 4.8 to 9.7 0.283 7.19 2.44 62.0 Powder-coated steel

130 to 200 9.0 to 13.8 0.331 8.41 2.250 57.2 Powder-coated steel

MR98H,

MR98HD

and

MR98HDP

3/4

and 1

20 and

15 to 35 1.0 to 2.4 0.306 7.77 4.00 102 Powder-coated steel

25 to 75 1.7 to 5.2 0.343 8.71 4.00 102 Powder-coated steel

25

70 to 140 4.8 to 9.7 0.406 10.3 4.00 102 Powder-coated steel

130 to 200 9.0 to 13.8 0.468 11.9 3.75 95.3 Powder-coated steel 1L380127082 Blue

15 to 35 1.0 to 2.4 0.306 7.77 4.00 102 Powder-coated Stainless steel 1E3989X0052 Yellow

3/4

and 1

20 and

25 to 75 1.7 to 5.2 0.375 9.53 3.88 98.6 Stainless steel 1K762537022 Unpainted

25

70 to 140 4.8 to 9.7 0.437 11.1 4.00 102 Stainless steel 11A8269X012 Unpainted

5 to 35 0.34 to 2.4 0.468 11.9 6.562 167 Powder-coated steel

1-1/2

and 2

and 50

20 to 65 1.4 to 4.5 0.500 12.7 6.50 165 Powder-coated steel

40

50 to 100 3.4 to 6.9 0.562 14.3 6.562 167 Powder-coated steel

75 to 170 5.2 to 11.7 0.625 15.9 6.565 167 Powder-coated steel

MR98HH

MR98HHD

1. All springs may be backed o󰀨 to 0 psig / 0 bar. However, highest capacities and best performances are obtained by using these springs in their recommended ranges.

2. Springs meet NACE MR0175-2002, NACE MR0103 and NACE MR0175/ISO 15156 requirements only for applications in which the spring is not exposed to the sour gas.

3. Available in Inconel

4. Spring range changes to 5 to 60 psig / 0.34 to 4.1 bar for the Inconel® option.

5. Spring range changes to 50 to 120 psig / 3.4 to 8.3 bar for the Inconel® option.

1/4 NPT - - - - 150 to 375 10.3 to 25.9 0.281 7.14 4.125 105 Powder-coated steel 1N942227142 Unpainted

and

1/2 15 150 to 375

3/4

20

and 1

®

.

150 to 375 10.3 to 25.9 0.593 15.1 6.380 162 Chromium-silicon steel 1N9441X0022 Light gray

and 25

10.3 to 25.9 0.394 10.0 5.063 129 Powder-coated steel 1N943427142 Unpainted

(1)

SPRING WIRE

DIAMETER

SPRING FREE

LENGTH

SPRING MATERIAL

SPRING PART

(2)

(3)

(3)

(3)

(3)

(3)

(3)

(3)

(3)

(3)

(3)

(3)

(3)

(3)

(3)

(4)

(4)

(5)

(5)

NUMBER

ERCA04288A0 Yellow

ERAA01910A0 Green

ERAA01911A0 Red

ERAA02889A0 Blue

1E398927022 Yellow

1E399027142 Green

1E399127162 Red

ERCA04288A0 Yellow

ERAA01910A0 Green

ERAA01911A0 Red

ERAA02889A0 Blue

1E398927022 Yellow

1E399027142 Green

1E399127162 Red

1E792327092 Dark gray

ERCA04290A0 Black with light blue stripe

ERAA01893A0 Light gray

1P7888X0022 Black

SPRING COLOR

®

Inconel

is a mark owned by Special Metals Corporation.

6

MR98 Series

Table 4. Maximum Cold Working Pressures of Body Size and Materials

REGULATOR

TYPE

BODY SIZE

NPS DN psig bar psig bar psig bar

BODY AND

SPRING CASE

MATERIALS

Gray cast iron 60 4.1 60 4.1 50 3.4

MR98L/LD

MR98H/

MR98HD

1/4 NPT

1/2, 3/4, 1

1/2, 3/4, 1 15, 20, 25

1/4 NPT

1/2, 3/4, 1,

1-1/2, 2

1/2, 3/4, 1,

1-1/2, 2

- - - -

15, 20, 25

- - - -

15, 20, 25,

40, 50

15, 20, 25,

40, 50

Steel 150 10.3 150 10.3 125 8.6

Stainless steel 150 10.3 150 10.3 125 8.6

®

Monel

®

Hastelloy

C 150 10.3 150 10.3 125 8.6

Gray Cast iron 300 20.7 300 20.7 250 17.2

Steel 300 20.7 300 20.7 300 20.7

Stainless steel 300 20.7 300 20.7 300 20.7

®

Monel

®

Hastelloy

C 300 20.7 300 20.7 300 20.7

Aluminum-Bronze 300 20.7 300 20.7 300 20.7

MR98HDP

(4)(5)

1/4 NPT

1/2, 3/4, 1,

1-1/2, 2

1/2, 3/4, 1,

1-1/2, 2

- - - -

15, 20, 25,

40, 50

15, 20, 25,

40, 50

Steel 600 41.4 600 41.4 600 41.4

Stainless steel 550 37.9 550 37.9 550 37.9

®

Monel

®

Hastelloy

C 550 37.9 550 37.9 550 37.9

Aluminum-Bronze 550 37.9 550 37.9 550 37.9

Steel 400 27.6 400 27.6 400 27.6

Stainless steel 400 27.6 400 27.6 400 27.6

®

Monel

®

Hastelloy

C 400 27.6 400 27.6 400 27.6

MR98HH/

MR98HHD

1/4 NPT

1/2, 3/4, 1

(4)

1/2, 3/4, 1 15, 20, 25

- - - -

15, 20, 25

Aluminum-Bronze 400 27.6 400 27.6 400 27.6

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

2. Temperature, trim material and/or the body end connection may decrease these maximum pressures.

3. Maximum inlet pressure equals set pressure plus build-up.

4. Maximum di󰀨erential pressure between inlet pressure and loading pressure should never exceed 300 psig / 20.7 bar.

5. Meets API 614 requirements (with Stainless steel trim).

MAXIMUM

INLET PRESSURE

(3)

150 10.3 150 10.3 125 8.6

300 20.7 300 20.7 300 20.7

550 37.9 550 37.9 550 37.9

400 27.6 400 27.6 400 27.6

(1)(2)

MAXIMUM

OUTLET PRESSURE

MAXIMUM

SPRING CASE PRESSURE

Table 5. Temperature Capabilities

MATERIAL SEAT DIAPHRAGM O-RING

Nitrile (NBR)

Neoprene (CR)

Fluorocarbon (FKM)

(3)

Ethylenepropylene (EPDM)

Peruoroelastomer (FFKM)

PTFE

Metal

 



  

  

 

 

BODY MATERIAL

DIAPHRAGM

PROTECTOR

(1)(2)(5)

TEMPERATURE

°F °C

-40 to 180 -40 to 82

-40 to 180 -40 to 82

0 to 300,

Limited to 200°F for hot water

-18 to 149,

Limited to 93°C for hot water

20 to 275 -7 to 135

0 to 425 -18 to 218



-40 to 400 -40 to 204

-40 to 450 -40 to 232

TEMPERATURE

°F °C

Gray Cast iron -20 to 406 -29 to 208

(4)

WCC Steel

(4)

LCC Steel

Stainless steel

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

2. Pressure and/or the body end connection may decrease these maximum temperatures.

3. Not for use on steam service.

4. Meets API 614 requirements (with Stainless steel trim).

5. Special low temperature constructions for process temperatures between -76 to 104°F / -60 to 40°C are available by request. The low temperature construction passed Emerson
laboratory testing for lockup and external leakage down to -76°F / -60°C.

®

Monel

is a mark owned by Special Metals Corporation.

Hastelloy® C is a mark owned by Haynes International, Inc.

(4)

, Monel® or Hastelloy® C -40 to 450 -40 to 232

-20 to 450 -29 to 232

-40 to 450 -40 to 232

7

MR98 Series

WARNING

!

Failure to follow these instructions or
to properly install and maintain this
equipment could result in an explosion,

re and/or chemical contamination

causing property damage and personal
injury or death.

Fisher™ backpressure regulators,
relief and di󰀨erential relief valves must
be installed, operated and maintained

in accordance with federal, state and
local codes, rules and regulations and
Emerson instructions.

If a leak develops or if the outlet
continually vents gas, service to the
unit may be required. Failure to correct
trouble could result in a hazardous
condition. Only a qualied person shall
install or service the unit.

Installation, operation and maintenance

procedures performed by unqualied

person may result in improper adjustment
and unsafe operation. Either condition
may result in equipment damage or

personal injury. Call a qualied person

when installing, operating and maintaining

the MR98 Series backpressure regulators,
relief and di󰀨erential relief valves.

Introduction

Scope of the Manual

This manual provides instructions for the installation,
adjustment, maintenance and parts ordering
information of MR98 Series backpressure regulators,
relief and di󰀨erential relief valves. Instructions and
parts lists for other equipment mentioned in this
Instruction Manual are found in separate manuals.

Product Description

The MR98 Series backpressure regulator, relief and
di󰀨erential relief valves are suitable for multiple uid
mediums including liquid, gas, air and steam services.

Typical applications include use in but not limited to
wash tanks, small heaters, fuel and oil lines, air supply
system, test xtures and sterilizers.

Backpressure Regulator / Pressure Relief Valve—

Types MR98L, MR98H and MR98HH regulators are
direct-operated backpressure regulator/relief valve for
pressure control requiring constant outlet pressures
between 2 to 375 psig / 0.14 to 25.9 bar.

Di󰀨erential Pressure Relief Valve—Types MR98LD,
MR98HD, MR98HDP and MR98HHD regulators are
direct-operated di󰀨erential relief valve with di󰀨erential
pressure range from 2 to 600 psig / 3.4 to 41.4 bar.

See Tables 1 through 5 for detailed breakdown of the
various construction o󰀨erings.

Principle of Operation

Relief or backpressure valves respond to changes in
upstream pressure. Pressure changes register under
the diaphragm (see Figure 2) through a registration hole
in the valve body or through an external control line.
When the pressure increases above the spring setting,
the pressure underneath the diaphragm overcomes the
spring compression. This causes the valve plug to move
away from the orice. The ow path through the valve
is open and excess pressure is vented. When upstream
pressure drops below setpoint, the valve closes.

Di󰀨erential relief valves are used to maintain a
di󰀨erential pressure between the controlled pressure
and loading pressure of a system. The spring setting
determines the di󰀨erential.

The di󰀨erential relief valve responds to both controlled
pressure and loading pressure and opens or closes
as these pressures change. If the loading pressure
increases, pressure on the upper side of the diaphragm
increases. The valve plug moves closer to the orice
and restricts the ow through the relief valve. When
loading pressure decreases, pressure on the upper
side of the diaphragm decreases. This allows the valve
plug to move away from the orice and allow more ow
through the di󰀨erential relief valve (to atmosphere or
back into the system). The di󰀨erential relief valve opens
and closes in response to changes in the controlled
pressure. In this way, the di󰀨erential pressure between
the controlled and uncontrolled pressures is maintained.

8

INLET PRESSURE

OUTLET PRESSURE

ATMOSPHERIC PRESSURE

VENT

MR98 Series

ADJUSTING SCREW

CONTROL SPRING

DIAPHRAGM

VALVE PLUG

ORIFICE

M1240_12/2019

TYPE MR98H WITH INTERNAL

PRESSURE REGISTRATION

INLET PRESSURE

OUTLET PRESSURE

ATMOSPHERIC PRESSURE

METAL DIAPHRAGMS

SPRING

GASKET

FOR TYPE MR98H WITH TWO METAL DIAPHRAGMS

(ALSO TYPICAL OF TYPES MR98L AND MR98HH EXCEPT FOR

TYPE MR98L, 1/4 NPT BODY, 2 TO 7 psi / 0.1 TO 0.48 bar RANGE)

CONTROL LINE TAP

NPS 1/2 / DN 15 TYPE MR98H

WITH EXTERNAL

PRESSURE REGISTRATION

SPRING

TYPE MR98L (1/4 NPT BODY, 2 TO 7 psi / 0.14 TO 0.48 bar RANGE)

M1239_12/2019

SIDE AND INTERNAL VIEW OF

NPS 3/4 TO 2/ DN 20 TO 50

TYPE MR98H WITH EXTERNAL

PRESSURE REGISTRATION

(ALSO TYPICAL OF TYPE MR98L,

NPS 1/2 to 2 / DN 15 TO 50 BODIES)

METAL DIAPHRAGM

GASKET

WITH ONE METAL DIAPHRAGM

Figure 2. MR98 Series Operational Schematics

9

OUTLET PRESSURE

INLET PRESSURE

LOADING PRESSURE

MR98 Series

HANDWHEEL

CONTROL SPRING

LOADING PRESSURE

INLET TAP

DIAPHRAGM

VALVE PLUG

ORIFICE

M1242_12/2019

INLET PRESSURE
OUTLET PRESSURE

LOADING PRESSURE

CONTROL LINE TAP

TYPE MR98HD WITH EXTERNAL PRESSURE REGISTRATIONTYPE MR98HD WITH INTERNAL PRESSURE REGISTRATION

SPRING

GASKET

METAL DIAPHRAGMS

FOR TYPES MR98HD, MR98LD, MR98HDP AND MR98HHD WITH TWO METAL DIAPHRAGMS, ASSEMBLE DIAPHRAGM GASKETS UNDER AND

ABOVE THE METAL DIAPHRAGMS AS SHOWN ABOVE

Figure 2. MR98 Series Operational Schematics (continued)

LOW PRESSURE (FOR LOADING)

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CONTROLLED HIGH PRESSURE

TYPE MR98LD

Figure 3. Installation Schematics for Types MR98LD and MR98HD Relief Valves

LOADING PRESSURE

RELIEF OUTLET AND OPTIONAL

PIPING TO SYSTEM

MR98 Series

HIGH PRESSURE

UNCONTROLLED LOW PRESSURE

Figure 3. Installation Schematics for Types MR98LD and MR98HD Relief Valves (continued)

Installation

WARNING

!

Personal injury or system damage may

result if this backpressure regulator,
relief or di󰀨erential relief valve is
installed where service conditions
could exceed the limits given on
the Specications section and/or

regulator nameplate.

Additionally, physical damage to the

backpressure regulator or relief valve

may result in personal injury or property

CONTROLLED HIGH PRESSURE

PUMP

TYPE MR98HD

damage due to escaping of accumulated

gas. To avoid such injury and damage,
install the backpressure regulator or
relief 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 regulator constructions with a

spring case vent, the vent should be
kept open to permit free ow 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.

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