Nfpa 1042

1. Approval Standard
for
Waterflow Alarm Indicators
(Vane Type)
om
.c
a se
gb
Class Number 1042
in
in
tra
re
.fi
w
w
July 1970
w
©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.
om
For examining equipment, materials and services, FM Approval Standards:
.c
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
se
b) must be readily identifiable.
a
Continuance of Approval and Listing depends on compliance with the Approval agreement, satisfactory
gb
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.
in
FM Global Technologies LLC reserves the right in its sole judgement to change or revise its standards, criteria,
in
methods, or procedures.
tra
re
.fi
w
w
w

3. TABLE OF CONTENTS
I. SCOPE ........................................................................................................................................................................................ 1
II. GLOSSARY ................................................................................................................................................................................ 1
A. Vane ...................................................................................................................................................................................... 1
B. Body ..................................................................................................................................................................................... 1
C. Instantly Recycling Retard .................................................................................................................................................. 1
D. Instantly Recycling Retard .................................................................................................................................................. 2
1. Location ............................................................................................................................................................................ 2
2. Performance ...................................................................................................................................................................... 2
III. REQUIREMENTS ................................................................................................................................................................... 3
A. Performance ......................................................................................................................................................................... 3
B. Friction Loss ........................................................................................................................................................................ 3
om
C. Vane Assembly ..................................................................................................................................................................... 3
E. Rated Working Pressure ....................................................................................................................................................... 4
F. Assembly ............................................................................................................................................................................... 4
.c
G. Wiring Diagrams .................................................................................................................................................................. 4
se
H. Enclosure .............................................................................................................................................................................. 4
IV. MATERIALS ............................................................................................................................................................................ 4
a
V. MARKING .................................................................................................................................................................................. 4
gb
APPENDIX APPROVAL MARKS .............................................................................................................................................. 5
in
in
tra
re
.fi
w
w
w

4. July 1970 1042
I. SCOPE
The waterflow alarm indicator with instantly recycling retard is used in a wet pipe sprinkler system to sound an
electrical alarm when one or more sprinklers operate.
FM Approval is based on examination and tests of production samples, inspection of the manufacturing 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
to be essentially equivalent or superior in performance.
om
.c
II. GLOSSARY
a se
The waterflow alarm indicator is made up of the vane, body, switch, and instantly recycling retard.
gb
A. Vane
in
in
The submersible vane is moved by the water flow. The movement is transmitted through suitable levers to open
or close switch contacts.
tra
B. Body
re
.fi
The body’s primary functions are to:
1. Provide support for levers between the vane and the switch.
w
2. Permit strapping the indicator to the pipe.
w
3. Provide a support for the switch.
w
C. Instantly Recycling Retard
This device operates, after a predetermined time has elapsed from the initial movement of the vane, to sound the
alarm.
1. There shall be no mechanical failure nor any appreciable change in the operating characteristics as a result
of this test.
2. The vane assembly shall be subjected to the following forward flow rates for 30 minutes.
FM APPROVALS 1

5. 1042 July 1970
Indicator Flow
Size-in. gpm
2 150
2 1⁄ 2 250
3 400
4 750
5 1000
6 1500
8 3000
There shall be no mechanical failure nor any appreciable change in the operating characteristics as a result of
this test.
om
When designing vane assemblies the following factors should be taken into consideration:
1. Reverse flow conditions — occasioned by draining sprinkler system or break in fire service main.
.c
2. Ample clearance between vane periphery and inside diameter of pipe.
se
D. Instantly Recycling Retard
a
gb
1. Location
It may be designed as an integral part of the indicator or it may be in a separate enclosure detached from the
in
indicator.
in
2. Performance
tra
The retard shall be these characteristics:
re
a. When the initial water flow occurs, the retard shall operate to delay the electric alarm for any pre-
selected period of 0-60 seconds. While an adjustable time delay of 0-60 seconds is preferable, a time delay
.fi
having a maximum limit of 120 seconds will be acceptable. Suitable instructions indicating means for
increasing or decreasing the retard shall be provided.
w
b. In the event the water flow ceases before the completion of the pre-selected time delay, the retard shall
w
automatically reset in such a manner that the entire retard cycle must be repeated when water flow again
w
occurs.
c. Contacts shall be arranged to permit operation on either open or closed circuits.
2 FM APPROVALS

6. July 1970 1042
III. REQUIREMENTS
A. Performance
Waterflow alarm indicators shall be so designed that they may be installed in either horizontal or vertical pipe
and that after proper initial factory adjustment they will:
1. Operate at a rate of flow between 4 and 20 gpm at any service pressure between 20-100 psig.
2. Operate on any flow rate in excess of minimum flow to give alarm.
3. Not operate at flows less than 4.0 gpm.
5. Transmit successive alarms without manual resetting.
om
B. Friction Loss
The loss in pressure passed the indicator shall not exceed 5.0 psi at the following flows:
.c
se
Indicator Flow
Size-in. gpm
2
a 150
gb
2 1⁄ 2 250
3 400
in
4 750
5 1000
in
6 1500
tra
8 3000
re
The need for running friction loss tests will be determined after an examination of a sample indicator.
.fi
C. Vane Assembly
w
w
Vane assemblies shall have sufficient mechanical strength to resist flows created by fluctuating water pressures
and operation of several sprinklers.
w
To evaluate the design, a sample 6 in. indicator—considered representative of the line—shall be subjected to the
following tests:
1. The vane assembly will be subjected to 100,000 flexes. A single flex involves moving the van in the
forward direction through an angle of 45° from its ‘‘normal’’ position (at zero flow) and then permitting
it to return to ‘‘normal’’. Rate of flexes shall be approximately 18-20 per minute.
A rubber faced roller (approximately O.D. of 3 in.) connected to the end of an air powered oscillating rod
will be arranged to strike the vane at its center when it is in the ‘‘normal’’ position. The roller moves at
all times in a direction perpendicular to the plane of the vane when in its ‘‘normal’’ position.
FM APPROVALS 3

7. 1042 July 1970
E. Rated Working Pressure
Indicators shall be designed for a rated working pressure of 175 psi.
To determine design adequacy, a 6 in. sample will be hydrostatically tested at 700 psi for five minutes. There
shall be no failure as a result of this test.
F. Assembly
Indicators shall be designed so that when installed the vane will always be at right angles to the water flow.
Whenever practical, the use of asymmetrical parts shall be employed.
om
G. Wiring Diagrams
Schematic electrical wiring diagrams shall be attached to the inside cover of each indicator.
.c
se
H. Enclosure
a
A drip tight enclosure shall be provided to protect the switch(es) and associated wiring.
gb
in
in
tra
IV. MATERIALS
re
All materials used in the construction of the indicator and retard shall be suitable for the intended application.
.fi
Special attention should be given to the selection of proper materials for use in water to avoid ‘‘galvanic’’ action.
w
The use of materials which change part dimensions from water absorption should be avoided in situations where
such change may interfere with operating characteristics.
w
w
V. MARKING
A corrosion resistant nameplate shall carry the following data:
name, abbreviation or trademark of the manufacturer, size, model designation, and electrical ratings. A direc-
tional arrow shall be provided to ensure correct installation. The arrow may be placed on the enclosure or the
saddle.
4 FM APPROVALS

8. July 1970 1042
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
om
to FM Approvals as an Approval mark when
used with the word ‘‘Approved.’’
.c
2) The FM Approval logomark has no minimum
se
size requirement, but should always be large
enough to be readily identifiable.
a
gb
3) Color should be black on a light background or a
reverse may be used on a dark background.
in
in
For Cast-On Marks
tra
4) Where reproduction of the mark described
above is impossible because of production
re
restrictions, a modified version of the diamond is
suggested. Minimum size specifications are the
.fi
same as for printed marks. Use of the word
‘‘Approved’’ with this mark is optional.
w
w
w
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
FM APPROVALS 5