The document provides standards for approving alarm check valves and retard chambers. It outlines performance requirements, design criteria, clearances, materials, and markings. An alarm check valve must activate alarms between 4-20 gpm and withstand pressures up to 175 psig. It must have a check valve, clapper, drain, and taps. A retard chamber provides a 10-30 second alarm delay at minimum flow and connects alarms to the system. It must withstand 150 psig and have supports, screens, and a manual control valve.

1. Approval Standard
for
Alarm Check Valves
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Class Number 1041
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July 1970
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©2002 FM Global Technologies LLC. All rights reserved.

2. Foreword
FM Approvals are intended to verify that the products and services described will meet stated conditions of
performance, safety and quality useful to the ends of property conservation. The purpose of FM Approval
Standards is to present the criteria for FM Approval of various types of products and services, as guidance for
FM Approvals personnel, manufacturers, users and authorities having jurisdiction.
Products submitted for Approval shall demonstrate that they meet the intent of the Approval Standard, and that
quality control in manufacturing and/or applications shall ensure a consistently uniform and reliable product or
service. FM Approval Standards strive to be performance-oriented and to facilitate technological development.
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For examining equipment, materials and services, FM Approval Standards:
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a) must be useful to the ends of property conservation by preventing, limiting or not causing damage
under the conditions stated by the Approval listing; and
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b) must be readily identifiable.
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Continuance of Approval and Listing depends on compliance with the Approval agreement, satisfactory
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performance in the field, on successful re-examinations of equipment, materials, and services as appropriate, and
on periodic follow-up audits of the manufacturing facility or service/application.
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FM Global Technologies LLC reserves the right in its sole judgement to change or revise its standards, criteria,
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methods, or procedures.
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3. TABLE OF CONTENTS
I GENERAL .................................................................................................................................................................................... 1
A Purpose and Intent ................................................................................................................................................................ 1
B Glossary ................................................................................................................................................................................. 1
II ALARM CHECK VALVE ......................................................................................................................................................... 1
A Performance .......................................................................................................................................................................... 1
B Design .................................................................................................................................................................................... 2
1. Check Valve ...................................................................................................................................................................... 2
2. Clapper and Arm .............................................................................................................................................................. 2
3. Hinge Pin .......................................................................................................................................................................... 3
4. Body, Seat Ring ................................................................................................................................................................ 3
5. Clapper Facing .................................................................................................................................................................. 3
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6. Auxiliary Check Valves .................................................................................................................................................... 3
C Clearances ............................................................................................................................................................................. 3
1. Clapper and Body ............................................................................................................................................................. 3
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2. Clapper Arm and Body .................................................................................................................................................... 3
3. Hinge Pin — Clapper Arm .............................................................................................................................................. 3
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D Materials ................................................................................................................................................................................ 3
E Markings ................................................................................................................................................................................ 4
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III RETARD CHAMBER .............................................................................................................................................................. 4
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A Performance .......................................................................................................................................................................... 4
B. Design ................................................................................................................................................................................... 4
1. Body .................................................................................................................................................................................. 4
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2. Screen ................................................................................................................................................................................ 4
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3. Support .............................................................................................................................................................................. 4
4. Alarm Connection ............................................................................................................................................................. 4
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5. Manual Control Valve ...................................................................................................................................................... 5
C Clearances ............................................................................................................................................................................. 5
D Materials ................................................................................................................................................................................ 5
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E Marking ................................................................................................................................................................................. 5
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APPENDIX APPROVAL MARKS .............................................................................................................................................. 6
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4. July 1970 1041
I GENERAL
A Purpose and Intent
An alarm check valve is used to hydraulically activate a mechanical and/or electrical alarm when one or more
sprinklers operate.
FM Approval is based on examination and tests of production samples, inspection of the manufacturing and/or
quality control facilities, and satisfactory field experience. Particularly considered are functional suitability,
adequacy of design and workmanship, uniformity and dependability of production, effectiveness of quality
control, and assurance of service and replacement parts.
These requirements are guides. Mere conformity does not assure approval; other considerations may control. Nor
is strict conformity necessary; devices having different characteristics may be considered and approved if shown
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to be essentially equivalent or superior in performance.
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B Glossary
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‘‘Alarm Check Valve’’ as used in this standard means a combination of a check valve and retard chamber which,
together, will produce a continuous alarm when water flows.
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II ALARM CHECK VALVE
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A Performance
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The valve shall:
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a — operate in either a horizontal or vertical pipe line.
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b — activate the hydraulic and electrical alarms at a rate of flow between 4 and 20 gpm at any water
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supply pressure between 20-100 psig.
c — activate the alarms at any rate of flow in excess of the minimum flow to give alarm
d — not activate the alarms at flows less than 4.0 gpm
e — discontinue alarms when water flow stops
f — activate successive alarms without manual resetting
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5. 1041 July 1970
B Design
1. Check Valve
a — The body shall have a hand hole with cover (1). The hand hole opening shall be large enough to
permit easy access to and removal of all working parts including the clapper (2).
b — The interior of the valve body shall preferably have a straight waterway. The area of the waterway
at any point within the body shall be not less than 60% of the nominal area of the pipe to which the
valve is to be connected. The loss in pressure across the valve shall not exceed 5.0 psig at the
following flows:
Valve Sizes Flow
inches gpm
2 150
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2 1⁄ 2 250
3 400
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4 750
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5 1000
6 1500
8
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3000
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c — The valve body shall have a drain connection (4) so that it will serve to drain all water from the
system piping with the alarm valve installed in either the horizontal or vertical position.
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The drain size shall be as follows:
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4 in. valves and larger — 2 in. drain
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21⁄2, 3, and 31⁄2 in. valves — 11⁄4 in. drain
d — The body shall have two 1⁄4 in. pipe tap connections for gauges. One connection shall be below the
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clapper and the other above.
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e — The body end flanges shall conform in dimensions and drilling to the national recognized standard.
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f — The body shall have a rated pressure of 175 psig.
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2. Clapper and Arm
The clapper shall be of ample strength to withstand water pressures ranging from 30 to 175 psig.
With the clapper on its seat and the inlet of the valve open to atmosphere, a hydrostatic pressure of 200%
of rated working pressure will be applied to the clapper for 5 minutes. There shall be no fracture or
permanent distortion as a result of this test.
The clapper with arm shall be designed so that it will close when no water is flowing through the valve.
The clapper and arm shall be joined in such a manner so that the clapper will seat properly.
If the clapper arm is of iron, bushings shall be provided in the hub of the clapper arm where the hinge pin
passes through it.
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6. July 1970 1041
3. Hinge Pin
The clapper arm must be supported by a hinge pin (6).
4. Body, Seat Ring
The face of the body seat ring shall be at least 1⁄8 inch higher than the surrounding metal into which the
ring is placed. The seat ring shall be at least 1⁄4 in. wide.
5. Clapper Facing
a. Metal
Metal clapper facings (finished seating surface) shall have a minimum width of 1⁄4 inch.
b. Rubber
Rubber clapper facings shall be clamped at least 1⁄2 in. at the inner edge. They shall be wide enough to
overhang the seat at least 1⁄8 in. on the outside, and shall be backed-up their full width by a finished surface
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on the clapper. The clamping ring (8) shall come to a stop against a shoulder on the clapper to prevent
distortion of the rubber.
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6. Auxiliary Check Valves
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Some manufacturers of alarm check valves attach an auxiliary check valve (9) to the main clapper, whose
purpose is to permit small flows of water to pass through without lifting the main clapper.
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When these valves are encountered, a special investigation will be made to determine their suitability for
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their intended application.
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C Clearances
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1. Clapper and Body
A clearance of 3⁄4 in. shall be provided between the outer edge of the clapper and the inside of the body
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for every position of the clapper from wide open to closed.
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2. Clapper Arm and Body
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A clearance of at least 1⁄2 in. shall be provided between the ‘‘hub’’ of the clapper arm and the inside of the
body. The ‘‘hub’’ of the clapper arm is that portion surrounding the hinge pin. (See Appendix)
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The length of the clapper arm hub should be 1⁄16 in. less than the distance between the vertical faces of the
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hinge pin bearings in the body.
3. Hinge Pin — Clapper Arm
A 1⁄32 in. clearance shall be maintained between the hinge pin and the holes in the hub of the clapper arm.
D Materials
All materials used in the construction of the alarm check valve shall be suitable for the intended application.
The possibility of corrosion (chemical or electrochemical) will be the subject of a special investigation.
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7. 1041 July 1970
E Markings
Valves must be plainly marked with the name or trade-mark of the manufacturer, the nominal size of the valve,
the year of manufacturer, a distinctive model number or letter, and the rated working pressure. This marking shall
be in raised cast letters on the valve body.
A serial or shop number should be placed on the valve body. This number may be stamped on.
A directional arrow shall be provided to indicate the direction of the flow.
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III RETARD CHAMBER
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A Performance
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This chamber shall be designed to provide a 10-30 second alarm time delay when the flow of water from the
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system is at the minimum rate required to give an alarm. This time delay excludes the time required for the water
to flow from the check valve to the retard chamber and also from the retard chamber to the alarm devices. The
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time required to draw off excess pressure above the valve is also excluded.
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B. Design
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1. Body
The body shall have a rated working pressure of 150 psig minimum.
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2. Screen
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Where screens are provided at the inlet to the retard chamber, the largest dimension of the holes in the
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screen shall be 1⁄16 in. less than the diameter of the smallest orifice to be protected by the screen. The total
area of the openings in the screen should be twenty or more times the cross sectional area of the opening
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which the screen is designed to protect.
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3. Support
The retard chamber shall have suitable supports for mounting. Piping ordinarily used in retard chamber
connections must not be the sole means of support.
4. Alarm Connection
The retard chamber should be so designed that 3⁄4 in. piping can be used to connect the alarm devices
to it.
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8. July 1970 1041
5. Manual Control Valve
A manually operated control valve shall be installed in the line between the alarm valve and retard
chamber.
The valve, when wide open, shall have a waterway at least equal to the nominal area of the pipe in which
it is connected.
The valve shall be of a type, whose position is readily apparent by visual examination (open or closed).
C Clearances
When moving parts are used in the design of a retard chamber, the clearances will be the subject of a special
investigation.
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D Materials
The materials used in the construction of the retard chamber shall be suitable for the intended application. The
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possibility of corrosion (chemical and electrochemical) will be the subject of a special investigation.
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E Marking
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The retard chamber shall be plainly marked with the name or trade-mark of the manufacturer, and a distinctive
model number. This marking shall be in raised cast letters. A serial or shop number and the year of manufacture
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should be stamped on.
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FM APPROVALS 5

9. 1041 July 1970
APPENDIX
APPROVAL MARKS
REPRODUCTION ART: FM Approval Marks
For use on nameplates, in literature, advertisements,
packaging and other graphics.
1) The FM Approvals’ diamond mark is acceptable
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to FM Approvals as an Approval mark when
used with the word ‘‘Approved.’’
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2) The FM Approval logomark has no minimum
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size requirement, but should always be large
enough to be readily identifiable.
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3) Color should be black on a light background or a
reverse may be used on a dark background.
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For Cast-On Marks
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4) Where reproduction of the mark described
above is impossible because of production
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restrictions, a modified version of the diamond is
suggested. Minimum size specifications are the
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same as for printed marks. Use of the word
‘‘Approved’’ with this mark is optional.
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NOTE: These Approval marks are to be used only in conjunction with products or services that have been
FM Approved. The FM Approval marks should never be used in any manner (including advertising, sales or promotional
purposes) that could suggest or imply FM Approval or endorsement of a specific manufacturer or distributor. Nor should
it be implied that Approval extends to a product or service not covered by written agreement with FM Approvals. The
Approval marks signify that products or services have met certain requirements as reported by FM Approvals.
Additional reproduction art is available through
FM Approvals
P.O. Box 9102,
Norwood, Massachusetts 02062
USA
6 FM APPROVALS