Maxitrol MR212H User Manual

M/MR Modulating Valves

For Atmospheric, Infrared, and Direct Fired Burners

TABLE OF CONTENTS

Description/Specications..................................................... 1

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

Direct Fired Applications (Negative Pressure) ..................... 2

Direct Fired Applications (Positive Pressure) ...................... 3

Indirect Fired Applications ..................................................... 3

‘H’ Sufx M/MR Valves ......................................................... 3

Applications Table ................................................................. 4

Dimensions .......................................................................... 5

Capacities ............................................................................ 6

Typical Gas Trains ............................................................... 7

Typical Installations ............................................................. 7

Model Designations ............................................................. 7

design certied

DESCRIPTION

Models:

M M411, M411H, M511, M511H, M611, M611H, M420,

M420H, M520, M520H, M620, M620H, M451, M551,
and M651.

MR MR212D, MR212E, MR212G, MR212H, MR212J

(Flanged), MR251D, MR251E, MR251G, MR410,
MR410-1, MR410H, MR410H-1, MR510, MR510-1,
MR510H, MR510H-1, MR610, MR610-1, MR610H,
and MR610H-1.

NOTE: “H” sufx models for use with LP and other applications:

M420H, M520H, M620H, MR410H-1, MR510H-1, MR610H-1

• Absolutely NO EXTERNAL MECHANICAL ACTIVATION required.

• MR Valve (only) performs dual function of modulation and
pressure regulation.

• Provides innite, continuous ame adjustment.

• May be factory installed or added in the eld.

• Capacities to 30,000 CFH.

• Available in a wide range of body styles and pipe sizes.

• Designed for use with the Maxitrol Selectra
systems - or SC11 Signal Conditioners convert computer/PLC
controller signals if standard Maxitrol companion controls are not
specied.

Whether your needs are problem-free stabilized area heating,
elevated heating, consistent higher baking/drying temperatures or
other process applications, maintaining consistent temperatures is
no longer a problem.

®

series of modulation

Figure 1 : MR212

SPECIFICATIONS

Gases:

Natural, Manufactured, Mixed, Liqueed Petroleum and Liqueed
Petroleum Gas Air Mixtures. H, H-1 models for use with Liqueed
Petroleum and other applications.

Certications:

M611, MR212D, E, & G with Series 14: CSA listed to certify
compliance with nationally published safety, construction, and
performance standards.

M411, M420, M420H, M451, M511, M520, M520H, M611, M620,

M620H, MR212D, E, G, & J with AD1094 controls: CSA listed to
certify compliance with nationally published safety, construction,
and performance standards.

MR410, MR410H-1, MR510, MR510H-1, MR610, and MR610H-1:
CSA certied to Z21.18 and CSA 6.3-M82.

M611, MR212D, E, & G: UL recognized for compliance to nationally
published safety, construction, and performance standards.

Vent:

Models M411, M511, M611, M420, M520, M620, M420H, M520H,
M620H, MR410H-1, MR510H-1, MR610H-1, M551, M651:
Vertical vent outlet 1/8” NPT - 12A06 installed.

Models MR212 and MR251: Two vents located in upper housing,
both equipped with vent limiting means.

The unique Modulator or Modulator/Regulator valve, the heart of
the Selectra
precise, non-uctuating, instantaneous temperature control without
requiring a motor or mechanically driven buttery valve.

© 2010 Maxitrol Company, All Rights Reserved

®

Electronic Gas Flame Modulating System, provides

1

Ambient Limits:

Operating ......................................... -40º to 125ºF (-40º to 50ºC)

Non-operating .................................. -50º to 185ºF (-45º to 85ºC)

Mounting:

Must be mounted in upright position in horizontal pipe run,
downstream of all other controls except high pressure cut-off
switch if used (see Typical Installations, page 7).

M/MR Series Literature

INTRODUCTION

To evaluate which valve will satisfy your needs, it is necessary to
determine the application. The rst, and most basic breakdown, is
direct versus indirect red appliances.

Direct red units do not have a heat exchanger and all products
of combustion generated by the gas burning device are released
directly into the airstream being heated. They are commonly used
in space heating or make-up air applications, process drying, and
baking ovens.

Direct red burners have raw gas injected into the burner and the
burner relies entirely on the air being pulled across the burner for
combustion air. It may take advantage of the mixing effects of the
blower by using a pull through system which locates the burner
on the suction side of the blower. This means the air being pulled
across the burner is at a negative pressure (usually not greater than

-1.5” w.c.). Other direct red applications may use a push through
system, which locates the burner downstream from the blower.
This means the air being pushed across the burner is at a positive
pressure (usually not greater than 3” w.c.).

Direct red burners can be of extremely high turn down ratios, in
some instances, 30:1. The high turn down ratio allows the minimum
temperature rise to be low enough that the unit does not have to be
cycled on and off to maintain temperature.

Indirect red appliances use a heat exchanger and all products
of combustion generated by the gas burning device are vented
outdoors. They are usually supplied with an atmospheric burner or
a power burner.

With an atmospheric burner, the air being supplied to the burner
is at atmospheric pressure. They have limited turndown ratios
(maximum input: minimum input) of usually 3:1 or 4:1. Due to the
limited turndown ratio, the minimum temperature rise cannot be
held low enough, and as a result, the main gas valve must usually
be cycled to maintain temperature.

A power burner is a burner in which either the gas, air, or both
are supplied at pressures exceeding line pressure for gas and
atmospheric pressure for air. Maintaining the proper gas-air mixture
for modulation usually requires pressure control of both the air and
gas. Burners of this type are usually not capable of modulation with
the Maxitrol Selectra® system. (See Exa Star modulating valves or
ratio (zero) regulators for these applications.)

With the main valve closed, an adjustable bypass provides a
minimum ring rate to the burner whenever the safety shut-off
valve(s) is open. This is low re to the heater. Since the pressure
regulator maintains a constant supply pressure, the minimum
ring rate is also held constant. The MR212’s regulator is
an integral component while a seperate upstream pressure
regulator is required for the M411, M511, and M611.

As voltage is applied to the control’s solenoid, a magnetic force
is applied to the plunger. The plunger in turn pushes down on
the main diaphragm of the M411, M511, and M611 valves or
allows pressure to develop in the upper chamber of the MR212
valve. These forces on the main diaphragm are very similar to
the spring loading of a gas pressure regulator. When the force
is sufcient to overcome the counter spring, the main valve
will open and gas will ow through the main valve in addition
to owing through the bypass. With sufcient voltage, the main
valve (modulator valve for the MR212) will fully open and the
pressure regulator will limit the burner pressure to the desired
amount, thus establishing a controlled maximum high re
condition.

We now have two extremes. The rst is low re with no force
on the plunger and ow through the bypass only. The second
is high re with sufcient force on the plunger to fully open the
valve (modulator valve for the MR212), with the gas pressure
regulator controlling the maximum ring pressure. Force on
the plunger between these extremes results in modulated gas
ow. The voltage versus outlet pressure curve, throughout the
modulating range, is fairly linear.

There are also applications where it is desirable to have two
seperate high re burner settings. Typical applications would be
a two speed fan operation or LP natural gas change over. This is
accomplished by adding an adjustable resistance to the circuit,
thereby limiting voltage to the valve. Changing from one setting
to another is done by connecting a single pole single throw
switch (customer supplied) that when in the open position allows
the outlet pressure to be adjusted up to 2” w.c. below normal
maximum high re. Negative pressure valves designed for dual
pressure settings are designated with a “- 2” sufx (example:
MR212D-2). Field conversion kits (KT/10542) to modify single
pressure valves are also available.

The working voltage to operate the modulating controls can
be supplied by the A1014, A1024, A1044, A1494 and AD1094
Ampliers or the SC11 Signal Conditioner. (Refer to Bulletin
SEL1444_CC_EN, SEL94_CC_EN, and SC11_MS_EN.)

DIRECT FIRED

Valves designed for direct red applications (negative

pressure/pull through) M411, M511, M611, MR212D, MR212E,
MR212G, and MR212J.

These valves are designed exclusively for negative pressure (pull
through) applications. They use a counter spring to keep the valve in
the closed position despite the downward pull of negative pressure.
M411, M511, and M611 valves are set for applications up to 1.5”
w.c. and are not adjustable. MR212 valves are factory set for ap­plications up to -1.5” w.c. and are eld adjustable for up to -3.5” w.c.

© 2010 Maxitrol Company, All Rights Reserved

Valves designed for direct red applications (positive

pressure/push through) MR212D-1, MR212E-1, MR212G-1,
and MR212J-1.

The valve’s operating principles are identical to the negative
pressure MR212. The only difference is the valve has been
designed to operate on positive pressure (push through)
applications. Positive pressure valves designed for dual
pressure settings are designated with a “- 3” sufx (example:
MR212D-3).

2

M/MR Series Literature

INDIRECT FIRED

Valves designed to operate on indirect red atmospheric

burner applications M420, M520, M620.

These valves function in the same manner as the direct red M
valves. A pressure adjustment spring has been factory set to
obtain an outlet pressure slightly above atmospheric pressure (0.1”
w.c.) with the bypass closed and zero voltage being applied. The
minimum ow rate is now adjusted through the bypass.

NOTE: Minimum outlet pressure is always above 0.2” w.c.
Maximum outlet pressure is 7.0” w.c.

The valves are driven by the A1094 and AD1094 Ampliers or
SC11 Signal Conditioners. (Refer to Bulletin SEL94_CC_EN &
SC11_MS_EN.)

Valves designed to operate on indirect red atmospheric

burner applications M451, M551, M651, MR251D, MR251E,
MR251G.

These valves function in the same manner as the direct red M
valves. Minimum input pressure is set using a minimum adjustment
spring - the valves do not use a bypass.

They are used in applications where the minimum input pressure
to burner is between 2.0” and 4.5” w.c. Maximum obtainable outlet
pressure is 7.0” w.c. above minimum input pressure.

‘H’ SUFFIX MODELS

Valves designed with wider modulation span for use with

LP (liquid propane gas) and other applications MR410H-1,

MR510H-1, MR610H-1, M420H, M520H, M620H.

Can be congured for indirect red atmospheric burner applications,
as well as those with direct red burners.

‘H’ models are designed for applications where outlet pressure is
greater than 7” w.c. Minimum outlet pressure is factory set to 1.75”
w.c. - remaining set pressure is obtained through bypass. The ‘H’
models are capable of a total modulation span of as much as 10”
w.c. These models are not recommended for applications with a total
modulation span of less than 7” w.c. - the sensitivity of outlet pressure
change relative to voltage change could cause hunting to occur.

‘H-1’ models are designed for applications with a total modulation
span greater than 7” w.c. Minimum outlet pressure range of 1” to

2.8” w.c.

NOTE: Temperatures shown in text are for Maxitrol’s Selectra®

systems. Valves may be used for any temperature range
or application the user’s controller can handle. When using
valves for other ranges, a Maxitrol SC11 Signal Conditioner
can be used in conjunction with the valve. (Refer to Bulletin
SC11_MS_EN)

The valves are driven by the A1094 and AD1094 Ampliers or
SC11 Signal Conditioners. (Refer to Bulletin SEL94_CC_EN &
SC11_MS_EN.)

MR410, MR510, and MR610

These valves use two springs in order to set the high and low
re settings. One spring (min.) surrounds the solenoid and is
always in contact with the diaphragm assembly. The other spring
(max.) is located above the plunger. With zero voltage applied, the
minimum and maximum spring’s down force, along with plunger
weight, pushes down on the diaphragm thereby setting a regulated
high re. A seperate pressure regulator is not required. As voltage
is applied, the plunger pulls up sufciently until all plunger weight
and maximum spring force is removed. The pressure is now
controlled with the minimum spring setting giving a regulated low
re condition. Force on the plunger between the extremes results
in modulated gas ow. The voltage versus outlet pressure curve,
throughout the modulating range, is not linear.

These valves are driven with the A1010 or A1011 Amplier or
SC11 Signal Conditioners. (Refer to Bulletin SEL2030_2131_CC_
EN & SC11_MS_EN)

© 2010 Maxitrol Company, All Rights Reserved

3

DFM

System

Used With

Output Control Means

Standard Factory Setting (if applicable)

24, 44,

94, SC11,

Series 14,

Low Fire: adjustable orice bypass

High Fire: upstream pressure regulator setting

less pressure drop

NOTE: 7” w.c. (1.7 kPa) max outlet pressure

Low Fire: adjustable orice bypass

SC11

Series 3,

Series 94,

High Fire: upstream pressure regulator setting

less pressure drop

NOTE: 7” w.c. (1.7 kPa) max outlet pressure

NOTE: H models: 11” w.c. (2.7 kPa) max

outlet pressure

SC11

Series 94,

Low Fire: spring adjustment

Std. Model: 1.2” - 2.5” w.c. (0.30-0.62 kPa)

“-1” models: 2” - 4.5” w.c (0.50-1.1 kPa)

High Fire: upstream pressure regulator setting

less pressure drop

SC11

Series 94,

Low Fire: spring adjustment 2”- 4.5” w.c.

(0.50-1.1 kPa)

High FIre: maximum 7” w.c. (1.7 kPa) above

minimum setting

DFM

24, 44,

94, SC11,

Series 14,

Low re: adjustable orice bypass

High re: spring adjustment

High Fire Setting:

Std. model: 2 -5” w.c. (0.50-1.25 kPa)

reduced to 0-3” w.c. (0-0.75 kPa)

“-2” model: 2” - 5” w.c. (0.50-1.25 kPa)

reduced to 0-3” w.c. (0-0.75 kPa)

Low re: spring adjustment

High re: spring adjustment

Std. model: 2” - 5” w.c. (0.50-1.25 kPa)

max-4” w.c. (1.0 kPa)

“-1” model: min-1.5” w.c. (0.38 kPa)

21, 30, 31

Series 20,

max-4” w.c. (1.0 kPa)

‘H-1’ model:

min outlet pressure = 1.75” w.c. (0.44 kPa)

max outlet pressure = 111” w.c. (2.7 kPa)

NOTE: ‘H-1’ models: 7.5” to 12” w.c. (1.87

to 3 kPa) max outlet pressure

systems.

®

Exposure

Maximum

Emergency

Pressure

Upstream

CSA

Required

Regulator

Limits

Operating

Inlet Pressure

Inlet

Tested*

Pressure

Increase in volt-

2.5 psi
(17 kPa)

Yes

Upstream

lator setting

pressure regu-

1/2 psi

(3.4 kPa)

to increase in

outlet pressure

age corresponds

Increase in volt-

2.5 psi
(17 kPa)

Yes

Upstream

lator setting

pressure regu-

1/2 psi

(3.4 kPa)

to increase in

outlet pressure

age corresponds

2.5 psi
(17 kPa)

Yes

Upstream

lator setting

pressure regu-

1/2 psi

(3.4 kPa)

to increase in

Increase in volt-

outlet pressure

age corresponds

(86 kPa)

No 12.5 psi

5 psi

(34 kPa)

- -

CSA

to increase in

Increase in volt-

outlet pressure

age corresponds

Inlet

Rated**

Pressure

12.5 psi

(86 kPa)

No

5 psi

(34 kPa)

5 psi

(34 kPa)

to increase in

Increase in volt-

outlet pressure

age corresponds

2.5 psi
(17 kPa)

No

1 psi

(7 kPa)

1/2 psi

(3.4 kPa)

to increase in

outlet pressure

age corresponds

Decrease in volt-

Application Function

Max.

Current

Draw

(amps)

Model

Number

Pressure) Burners

Direct Fired (Negative

0.4

0.5

M411

M511

Atmospheric Burners

0.6

0.4

0.7

M611

M420

M420H

as LP applications)

H Models for higher

outlet pressures (such

0.5

0.6

1.0

0.85

M520

M620

M520H

M620H

M/MR SERIES APPLICATIONS TABLE

© 2010 Maxitrol Company, All Rights Reserved

- where higher outlet

Atmospheric Burners

pressures are needed

0.4

0.5

0.6

M451

M551

M651

- where higher outlet

Atmospheric Burners

pressures are needed

0.4

MR251E

MR251D

MR251G

Pressure) Burners

Direct Fired (Negative

0.4

MR212J

MR212E

MR212D

MR212G

Atmospheric Burners

0.4

MR410

outlet pressure (such

H-1 models for higher

as for LP applications)

0.7

0.5

0.6

1.0

0.85

MR510

MR410H-1

MR610

MR510H-1

MR610H-1

* Where no ANSI standard currently exists, Maxitrol Controls have been CSA tested for use as a component of Maxitrol Selectra

**CSA Rated Inlet Pressures are established by ANSI Z21.18, CSA 6.3, and CSA 6.5 standards where applicable.

4

M/MR Series Literature

DIMENSIONS

B

B

Figure 2: MR410, MR410H-1, M411,

M420, M420H, M451

A

A

A

A

D

D

C

C

B

B

C

C

Figure 3: MR510, MR510H-1, M511,

M520, M520H, M551

D

D

B

B

B

B

C

C

Figure 4: MR610, MR610H-1, M611,

M620, M620H, M651

A

A

D

D

NOTE: Dimensions are to be used only as an aid in designing clearance for the valves.

Actual production dimensions may vary somewhat from those shown.

Model Number Swing Radius

MR410, MR410H-1, M411, M420, M420H, M451

MR510, MR510H-1, M511, M520, M520H, M551

MR610, MR610H-1, M620, M620H, M651

M611

MR212D, MR251D

MR212E, MR251E

MR212G, MR251G

MR212J (Not Shown Above) --

© 2010 Maxitrol Company, All Rights Reserved

3.1

(79)

4.3

(109)

5.7

(145)

6.2

(158)

8.1

(206)

8.6

(218)

10.4

(264)

5

A B C D

3.9

(100)

5.3

(135)

7.1

(180)

7.7

(196)

10.2

(259)

11.25

(286)

14.75

(375)

24

(610)

C

C

Figure 5 : MR212, MR251 (Same as MR212
except single by-pass)

Dimensions - Expressed in Inches (mm)

2

(51)

3.25

(83)

3.9

(99)

3.9

(99)

7

(178)

9.1

(232)

13.5

(343)

21.5

(546)

2.5

(54)

3.4

(86)

4

(102)

4

(102)

5.5

(140)

8

(203)

11.75

(298)

13.9

(352)

D

D

0.9

(24)

1.2

(30)

1.5

(37)

1.5

(37)

2.3

(59)

3

(76)

4.6

(118)

5.9

(149)

A

A

M/MR Series Literature

CAPACITIES

Flow Rate expressed in CFH (m3/h) - 0.64 sp gr gas, Pressure Drop expressed in inches w.c. (Pa)

NOTE: Consult with Maxitrol Company, for ows in excess of those shown below.

Model Number and

Pipe Size

MR410
MR410H-1
M411

M420†
M420H
M451

MR510
MR510H-1
M511†

M520‡
M520H
M551

MR610
MR610H-1

M620†
M620H
M651

3/8 X 3/8

1/2 X 1/2

1/2 X 1/2 --

3/4 X 3/4 --

3/4 X 3/4 -- -- --

1 X 1 -- -- --

100

(2.83)

0.33
(82)

0.27
(67)

150

(4.25)

0.75

(188)

0.61

(153)

0.17

(42)

0.12

(30)

200

(5.66)

0.30
(75)

0.21
(52)

250

(7.1)

-- -- -- -- -- -- -- -- -- --

0.47

(118)

0.32
(80)

0.14

(35)

0.12

(30)

300

(8.5)

0.67

(168)

0.47

(118)

0.20
(50)

0.16
(40)

350

(9.9)

0.92

(230)

0.64

(160)

0.27
(67)

0.22
(55)

400

(11.3)

--

0.83

(207)

0.36
(90)

0.29
(72)

450

(12.7)

-- -- -- -- --

0.45

(113)

0.37
(92)

500

(14.2)

0.56

(140)

0.45

(113)

600

(17.0)

0.81

(203)

0.66

(165)

† or ‡ Models to which min. ow applies. (Minimum ow maximum calculated ΔP = 3.5” w.c. [single by-pass])

Model Number

and Pipe Size

3/4 x 3/4

M611*

1 x 1

100

(2.83)

0.02
(5)

0.02
(5)

150

(4.25)

0.06
(15)

0.05
(12)

200

(5.66)

0.09
(23)

0.07
(18)

300

(8.5)

0.20
(50)

0.16
(40)

400

(11.3)

0.36
(90)

0.29
(72)

500

(14.2)

0.56

(140)

0.46

(115)

600

(17.0)

0.81

(203)

0.66

(165)

700

(19.8)

1.10

(275)

0.90

(225)

800

(22.7)

1.45

(363)

1.18

(295)

900

(25.5)

1.83

(458)

1.50

(375)

700

(19.8)

-- --

0.90

(225)

1000

(28.3)

--

1.85

(463)

750

(21.2)

1.00

(250)

CSA

Listed

1000

Min. Flow

†5-90

(14-250)

†5-125

(14-350)

‡5-185

(14-520)

†10-330
(28-930)

Min. Flow

10-330

(28-930)

Model Number and

Pipe Size

1 x 1

MR212D*

MR251D

MR212E*

MR251E

MR212G*

MR251G

*U.L. recognized
**Pressure Drop gures derived from CSA Maximum Listed Capacities in far right column (not ow at column top).

Model Number

and Pipe Size

MR212J 4 x 4

1¼ x 1¼

1½ x 1½

1½ x 1½

2 x 2

2½ x 2½

3 x 3 --

1000

(28.3)

(475)

(425)

(425)

6000

(170)

1.9

(475)

1500

(42.5)

1.9

1.7

1.7

2.9

(725)

2.3

(575)

2.2

(550)

-- --

-- -- -- -- --

8000

(227)

2.1

(525)

2000

(56.5)

4.9

(1225)

3.1

(775)

2.9

(725)

1.9

(475)

1.9

(475)

10000

(283)

2.4

(600)

2500

(70.8)

6.2**

(1550)

4.8

(1200)

3.9

(975)

2.4

(600)

2.1

(525)

12000

(340)

2.7

(675)

3000

(85.0)

--

5.9**

(1475)

5.4

(1350)

2.9

(725)

2.4

(600)

14000

(397)

3.1

(775)

3500

(99.0)

(875)

(675)

(475)

16000

(397)

(900)

5000

(142)

-- -- -- -- -- --

3.5

6.0**

(1500)

2.7

1.9

3.6

5.5

(1375)

2.2

(550)

2.1

(525)

18000

(510)

(1125)

4.5

6000

(170)

6.0**

(1500)

(650)

(575)

20000

(566)

(1350)

7000

10000

(198)

-- -- -- -- 4750

2.6

(750)

2.3

(650)

5.4

(283)

-- -- -- 5250

3.0

2.6

22000

(623)

(1650)

6.1

(1525)

4.6

(1150)

6.6

24000

(680)

7.8

(1950)

11000

(311)

-- 10000

5.6

(1400)

27000

(765)

9.9

(2475)

30000

(850)

12.4

(3100)

Min. Flow

Applies to

MR212’s only

25-300

(71-850)

25-300

(71-850)

50-450

(140-1270)

Min. Flow

1-1000

(3-2830)

CSA

Listed

2250

2750

3000

11000 --

© 2010 Maxitrol Company, All Rights Reserved

6

M/MR Series Literature

TYPICAL GAS TRAINS

Modulator (M) or Modulator-Regulator (MR) Valve: Mount in upright position in horizontal run of pipe, downstream of other controls - a
seperate gas pressure regulator must be used with any modulator (M) valve.

Figure 6 : M Valve-Regulator upstream of modulator valve

TYPICAL INSTALLATIONS

DIA-

PHRAGM

GAS

FLOW

PRESSURE

REGULATOR

VALV E

TO BURNERS

Figure 8 : If diaphragm type automatic gas valve is used with seperate
regulator, install MR valve downstream from diaphragm gas valve. Retain
regulator in manifold and adjust 2 or 3 turns to compensate for pressure
drop of MR valve.

GAS

FLOW

COMBINATION

CONTROL

TO BURNERS

MR

MR

Figure 7 : MR Valve-Modulator/Regulator Valve

MODEL DESIGNATIONS

Models having the letters B, H, M, R, or W, or a combination of
these sufx letters, indicates the design modication described
below:

B Both sides tted for low re adjustment.

H Capable of a total modulation span of as much as 10” w.c.

M PL parallel thread conforms to ISO 7-1.

Right side outlet - low re by-pass adjustment on right side.

R

Available on models: M411, M511, M420, and M520.

Indicates covered wire terminal connections, same as

W

M611. Available on models: M411, M511, M420, M520,
M620, M451, M551, and M651.

NOTE: Models M411, M511, and M611 are available with 1/8”

NPT connection for reading outlet pressure. Not availabe
on “B” models connection is located on opposite side of
by-pass adjustment (See Dimensions, page 5).

Figure 9 : If full combination control is used, install MR valve downstream.
Adjust regulator in combination control 2 or 3 turns to compensate for
pressure drop at MR valve.

GAS

FLOW

MR

SOLENOID

TO BURNERS

VALV E

Figure 10 : If solenoid type automatic gas valve is used with seperate
regulator, replace regulator with the MR valve.

NOTE: MR Valve must be in upright position, in horizontal run of
pipe only with pilot gas supply upstream.

7© 2010 Maxitrol Company, All Rights Reserved

M/MR Series Literature

Maxitrol Company
23555 Telegraph Rd., PO Box 2230
Southeld, MI 48037-2230

MMR_MT_EN_11.2010

8

www.maxitrol.com

© 2010 Maxitrol Company

All Rights Reserved