flowing; 2.9 pounds with 1000; 6.6 with 1500; 12 with
1500 and 26 with 3000. For 12-inch pipe, 2.6 pounds
with 1500 gallons flowing; 4.7 pounds with 2000 and 10
with 3000. Corrosion, sediment and sharp bends increase
these figures considerably.
Great care should be taken in laying underground pipe
to see that it is buried well below the frost line. The safe
depth varies with the location from 2 feet in the south
to 10 feet in northern Canada, measured from the top of
the pipe to ground level. The best local practice should
be followed, provided it has been found safe during the
recent cold winters, bearing in mind that there will prob-
ably be no flowage in these pipes most of the time.
All piping should be tested for two hours under 150
pounds pressure, or if normal pressure is to exceed 100
pounds, to a pressure at least 50 pounds above normal.
Pressure should be put on the pipes before the trench is
filled in if possible.
Care should also be taken in properly supporting the
pipe in poor soil, in anchoring the pipe on steep inclines
and in carefully filling in and tamping around aH under-
ground pipe when it is laid.
An alarm valve is a very inexpensive and valuable
addition to. the fire protection in a sprinklered risk and
is strongly advised for every equipment. It consists
of a device which is installed in the main sprinkler riser
and is arranged to actuate some form of alarm as soon
as water flows through the system. These alarms are
of two types: rotary gongs, operated like water wheels,
by the passage of water through them; and electric
gongs, operated by the movement of a check valve or
by the closing of an electric circuit through the action
of water pressure on a diaphragm. Alarm valves are
valuable for two reasons: they give an alarm when
sprinklers open on account of fire, thus acting as a fire
alarm; and they give warning in case of flowage through
the system for other causes such as a broken pipe, open-
ing sprinkler head, etc. For the latter reason they are
of great importance from a sprinkler leakage point of
view, and most companies insuring against this form
of loss require either an alarm valve in the system or
standard watchman's service in the risk insured.
There are two principal types of alarm valves that
have been successfully used. In one a check valve is
placed in the main water pipe and the movement of the
clapper when water begins to flow, transmitted usually
through a packed stem, is used to actuate the alarm.
In the other type a check valve is also used and this,
when in its normal position, closes an outlet to a small
138 AUTOMATIC SPRINKLER PROTECTION
pipe running to the alarm devices. This is accomplished
by having the small pipe run from a groove in the valve
seat, a horn in the water way or an auxiliary valve out-
side the main water way. In any type, a retarding or
interrupting element should be used to retard the alarm
long enough so that water hammer will not produce a
The early valves were of the first type and usually
had no retarding element. The most common variety
was that using a swing check with an arm attached
which extended through a stuffing box to a lever on the
outside. This lever was so arranged that when it was
moved forward by the opening of the check, a mechanical
gong was tripped or an electrical circuit connected to a
bell was completed.
This was a very crude form of alarm valve and par-
ticularly defective in the following points:
1. Sticking of the packed stem. The packing used to
make a tight joint often caused the stem to stick owing
to its age or to its being packed too tightly. In many
cases this sticking was great enough to cause a serious
menace to the equipment by obstructing the water way.
2. Susceptibility to false alarms. Any valve of this
character, having no retarding element, is very liable to
give false alarms from water hammer. A slight impulse
in the water would force the clapper off its seat and would
probably give an alarm if the device was adjusted to
operate for small flows.
3. Lack of sensitiveness. Where the movement of a
large check valve is used to give an alarm it is evident
that the amount of water necessary to feed one sprinkler
head would only open the valve a very small amount.
It is therefore very difficult to adjust the device so that
it will operate for small flows caused by the opening of
one or even two heads.
4. The valves were liable to stick open. This was
ALARM VALVES 139
especially the case where the lever was weighted so that
when it started to move the weight would carry the
clapper over to the wide open position.
In addition to the above the electrical and mechanical
gongs used at this time were crude and unreliable. The
mechanical gongs had to be rewound each time they
operated and this was frequently forgotten. Valves of
this type have not been installed to any extent for many
years and but few are now found in the field.
In 1881 Mr. J. C. Meloon of Providence patented an
alarm valve of the vertical check type in which the move-
ment of the clapper operated an auxiliary valve which
admitted water from below the check valve to a cham-
ber. The water pressure in the chamber actuated a
diaphragm which, when it moved, tripped the catch of
a mechanical alarm.
In 1884 Mr. Charles E. Buell patented a valve of the
packed stem type in which the lever attached to a swing
check started a train of clockwork actuated by a weight.
This rang a mechanical gong. The Walworth Manu-
facturing Co. also made some valves of this general
Another of the early valves of this type was the Neu.
This was a vertical check valve seating like a globe
valve on a horizontal seat. A spindle extended through
a stuffing box at the top and closed an electrical contact
when the clapper was raised by the flowage of water.
This had practically all the defects of the swing check
type except the liability to stick open.
The Grinnell Angle Alarm, so-called, was somewhat
similar to the Neu. It was a vertical check of the angle
type. A rod attached to the lower side of the check
valve contained a groove, and a horizontal pin passing
through a stuffing box to the outside of the casing rested
140 AUTOMATIC SPRINKLER PROTECTION
in this groove. When the valve opened the pin was
pushed a short distance forward thus making an elec-
trical connection or tripping a mechanical gong.
This valve was an improvement over the old swing
check as it was less subject to false alarms. The valve
could lift slightly without giving an alarm and there
was less chance of sticking. Like the older valve, how-
ever, it had no retarding element and was difficult to
adjust so as to be sensitive to small flows and at the
same time not to be subject to false alarms.
In. 1888 Messrs. R. Dowson and J. Taylor of Bolton,
England, patented in this country the well-known Eng-
lish Alarm Valve. This was manufactured by the Gen-
eral Fire Extinguisher Co. for many years and is still
used in a slightly modified form. It is also the basis of
several other valves and embodies perhaps the most
successful principle that has ever been used in alarm
valve construction. It consisted of a vertical check
valve having a grooved seat. A pipe extended from
the groove to a rotary gong actuated by the flow of water.
When the valve was seated, the groove was tightly cov-
ered by the clapper and no water could escape. When
the valve was raised by flowage in the system, the water
entered -the groove and flowed to the water rotary gong.
In the original valve there was no retarding chamber
and the valve was therefore somewhat subject to false
alarms from water hammer. There was, however, a
small compensating valve located in the main check
valve which allowed water in small quantities to pass
upwards through the alarm valve but not back again.
This was installed to prevent trouble from water ham-
mer by building up an excess pressure in the system
above the main check valve.
The same year (1888) Mr. Frederick Grinnell patented
a very ingenious device which, however, was never put
on the market so far as known. The principle involved
was apparently a very effective one for preventing false
alarms from water hammer although in case it failed to
work properly it completely blocked the water way.
It consisted of a double or balanced valve comprising
two self-packing pistons h h located several inches
apart and connected by a rod running in a guide. The
pipe from the water supply b' was connected between
GRINNELL ALARM DEVICE 1888.
the two pistons, when in their normal position, so that
there was an equal pressure on each, thus balancing the
The cylinder in which these two pistons could move
horizontally was connected at one end to the sprinkler
riser and at the other end to a pocket 6 3 normally full
of water. A rod i connected with the pistons extended
through the pocket and a stuffing box to the outside of
the casting. Here it came in contact with a valve sup-
plying a steam whistle. A small by-pass k extended
around the two pistons of the alarm valve connecting the
sprinkler riser with the pocket. In this by-pass was a
three-way cock I which when in its normal position left
a free way through the by-pass, thus equalizing the
water pressure in the riser and in the pocket.
142 AUTOMATIC SPRINKLER PROTECTION
This three-way cock was connected to a lever arm m
actuated by a flexible diaphragm o and connected by a
short piece of pipe to the riser. When in normal posi-
tion the two pistons spanned the inlet pipe and pre-
vented any flow of water into the riser. Any water
hammer or variation in pressure acted equally on both
pistons and gave no alarm. When, however, a sprinkler
operated the pressure in the riser was reduced. This
caused the diaphragm to drop, thus moving the lever
downward and changing the position of the three-way
cock so as to close the by-pass but open a passage from
the pocket to a waste pipe. This relieved the pressure
in the pocket thus causing the two pistons to move in
that direction to the limit of their travel. This opened
the main water way from the supply pipe into the riser
and at the same time operated the steam whistle.
The International valve was of a somewhat similar prin-
ciple to the English Alarm valve. Instead of a grooved
seat, however, a horn was used. This horn extended
from outside the casing to the under side of the main
clapper of a swinging check valve. When the clapper
was on its seat, it also closed the open end of the horn.
When the clapper was raised, the water flowed into the
horn, hence through the retarding chamber to the circuit
closer and rotary gong. The retarding chamber was,
however, of an entirely different principle from that used
in the English Alarm valve as will be described later.
The first Rockwood alarm valve was practically a copy
of the English valve. The present type has a grooved
seat and, in addition, a by-pass containing an auxiliary
valve to care for the small flows.
The Venturi valve made by the Venturi ^larm Co.,
and installed by the Manufacturers' Automatic Sprink-
ler Co. (later by the " Automatic " Sprinkler Co. of
America), is of a radically different principle from any
other alarm valve.
ALARM VALVES 143
There is a weighted swing check in the main water
way but no grooved seat or horn. There is a by-pass
around the check valve containing a Venturi tube, that
is a tube containing a restricted portion or throat.
Water flowing through such a tube has an increased
velocity accompanied by a decrease in pressure at the
throat. This difference in pressure is made use of to
give an alarm by piping one side of a mercury column to
the throat, and the other side to the full-sized pipe below
the throat. A heavy iron float rests on one side of the
mercury column and when water passes through the
by-pass, owing to flowage in the system, the float falls
and its movement opens an outlet which allows the
water to flow to the alarm devices.
In February, 1908, Mr. E. L. Thompson of the Man-
ufacturers' Automatic Sprinkler Co. patented an alarm
valve which operated entirely on account of reduction
of pressure in the system when a sprinkler opened. It
was a complicated device containing a balanced valve
which fell when the pressure was reduced thus allowing
water to pass into a pipe which operated an electrical
and water rotary gong. This was never used in prac-
tice so far as known.
Mr. Geo. E. Hibbard of Chicago patented a valve in
1903, which could be used either as an alarm or dry
valve. This depended upon an excess pressure being
maintained above the valve and was never used so far
In all types of alarm valves great care should be taken
in the matter of installation. Most of the valves on
the market have had a remarkably good record so far
as giving an alarm in case of fire is concerned, but the
record of false alarms has not been satisfactory. The
greater portion of this trouble has, however, been due
144 AUTOMATIC SPRINKLER PROTECTION
to defective installation. A few of the more important
points that are often overlooked are the following:
1. Vent for circuit closer. There should be a small
outlet about J inch in diameter located under each cir-
cuit closer so that when the water flow ceases the pres-
sure under the diaphragm will be released at once and
the circuit will be thereby broken. This also allows
the pipe from the diaphragm to drain quickly by admit-
ting air at the upper end. The vent should be piped
through a visible outlet and so arranged that water
discharged from it will do no damage.
2. All drips should run to the space under the build-
ing or out of doors in such a manner that the chance
of clogging or freezing will be reduced to a minimum.
Drips running to a sewer are liable to cause trouble by
the backing up of water which may operate the alarms.
When it is necessary to connect to a sewer, the drip
pipe should run into an open cup or into a pipe of larger
diameter, this latter pipe running to the sewer. The
top of the cup can be closed with a sliding cover if
desired and this, not being air-tight, will prevent any
back pressure from reaching the retarding chamber.
The piping should be arranged so that the end of the drip
can be easily inspected for leaks. If necessary a trap
can be placed in the large pipe that connects with the
sewer. The drip from the circuit closer can easily be
carried to the same drain pipe.
3. The water rotary gong should be located as near
the alarm valve as possible. If located at too great a
distance from, or at too great an elevation above, the
alarm valve, the loss of head entailed may cause trouble.
In case the length of pipe is over 15 feet it is, desirable to
enlarge it to at least 1 inch diameter. This pipe should
be arranged so that it will drain quickly.
There should be a substantial hood and screen over
the gong to prevent clogging by ice, birds' nests, etc.
These are usually supplied with the valve.
ALARM VALVES 145
RULES FOR DESIGNING AN ALARM VALVE
The following specifications give a general idea of
the requisites for a satisfactory alarm valve.
1. Must be capable of actuating and maintaining in operation
either mechanical or electrical devices, or both.
2. The electrical alarm type must be capable of actuating an
electrical circuit opener or closer, according to the character of the
alarm circuit to which it may be connected.
3. The combination electrical and mechanical type must operate
to set and maintain in operation both alarms, or either independently.
4. Must operate at all rates of water delivery from the system,
exceeding ten (10) gallons per minute.
5. The retarding factor must not exceed thirty (30) seconds.
The retarding factor is here defined as the time elapsing between
the first movement of water past the valve due to opening of a sys-
tem outlet and the completion of the act by which the valve actu-
ates the alarm devices; it is not construed as including the delay
incident to excessive lengths of connecting pipes leading to such
devices, or other delays which may be largely dependent in magni-
tude upon details of installation or excess pressure above the valve.
6. Must be equally operative, without special adjustment, at all
service pressures for which it is rated.
7. Must discontinue alarms on stoppage of flow.
8. Must be capable of transmitting successive alarms without
9. Must not spatter water upon the surroundings of the valve
nor cause waste of water.
10. Must not give false alarm under any variation in service
pressure for which it is rated.
11. Must be substantially constructed and not embody delicate
12. Must not waste water while in service and not in operation.
13. Must not depend on moving parts which are liable to become
stiffened by corrosion, other results of lapse of time or by misad-
14. Must be so designed as not to invite improper adjustment in
15. Must not require frequent renewal, or adjustment of parts.
16. Must have all working parts readily accessible for removal
17. Must be made up and shipped from the factory in such form
as not to be liable to incorrect installation or assembly.
146 AUTOMATIC SPRINKLER -PROTECTION
18. Must not be susceptible to accumulation of foreign matter.
19. Must not be liable to failure from the effects of corrosion,
sticking of parts or ordinary accumulation of sediment and other
foreign matter from the piping.
20. Must not possess sufficient differential properties to cause
danger of water columning in service or undesirable action in oper-
21. Must not depend, for proper action, on manually-wound
spring motors or any other form of motive power which is liable to
be out of commission when needed.
22. Electrical contact devices must be so protected from mois-
ture that they will be dry under all conditions short of actual sub-
merging of the apparatus.
23. Must not invite internal or external gagging. The necessary
test valves and devices must be as simple as possible. If of such
nature or so located that they may be carelessly left in condition to
render the alarm devices inoperative, provision must be made for
pad-locking or sealing them, in proper operative condition only.
24. Must not cause excessive loss of pressure by hydraulic
NATIONAL BOARD RULES FOR ALARM VALVES
See Sprinkler Rules Section G.
The National Board rules for alarm valves state that
every sprinkler system should contain an alarm valve
that will operate an electrical, a mechanical gong or
both. The character of the property and the local con-
ditions should determine just what bells should be used
and where they should be located. In a city risk the
electric bell should if possible be located in a fire de-
partment house or in a central station. It is also very
desirable to wire it on a closed circuit in such locations.
It is often advisable to omit the rotary gong when the
risk is located in a congested district on account of the
panic or the frightening of horses which might result
from the ringing of so large a gong.
In small towns or villages both electric and rotary
gongs are desirable and the electric bell should be at a
fire department house or in the dwelling of some inter-
ALARM VALVES 147
ested party. In some cases, the electric bell can be
located in the power house of some nearby plant where
there is some one on hand nights, Sundays and holidays.
The alarm valve should be so located that the supplies
from all automatic sources will pass through it. This
excludes steamer connections and occasionally pump
supplies although it is usually better practice to have
the pump water pass through the alarm valve. This
necessitates bringing all water supplies together below
the valve, as, for instance, bringing the tank supply
down to the basement level and connecting it with the
town water supply under the main gate valve and alarm
valve. It was formerly customary to feed the tank
supply into the top of the riser but this is not allowed
today, except in the case of risks having no other sup-
plies than gravity or pressure tanks. In this case, which
is sometimes found in cities having a waterworks sys-
tem of very light pressure, the alarm valve and con-
trolling gate valve may be located at the top of the
building thus doing away with the extra friction loss
due to the water flowing down to the low level and then
returning through the riser.
The wiring for electric bells should be in conformity
with the rules given in the National Board of Fire Un-
derwriters' pamphlet on Signalling Systems.
All alarm valves should be tested occasionally to make
sure they are in good working order. Once a week
should be often enough under any conditions and once
a month is frequently sufficient.
The principal sources of trouble to be looked for are;
the failure of the electric bell due to exhausted' bat-
teries, corrosion at bell or broken wire; the failure of
the rotary gong due to clogging at the outlet or binding
of parts; sticking at the seat of the valve. This latter
148 AUTOMATIC SPRINKLER PROTECTION
is infrequent, but occasionally occurs with valves hav-
ing a soft rubber seat especially if there is a heavy water
pressure on top of the clapper. The electric bell is by
far the most usual part of the device to get out of order,
largely due to battery trouble, and it is well to test this
as often as once a week. This can be done by short-
circuiting the wires without disturbing the alarm check
or the water rotary. A push button should be installed
for this purpose connected directly to the binding posts
at the circuit closer and not tapped into the wires run-
ning to the bell. In this way the entire circuit is tested
and if the main wires are corroded or broken off at the
binding posts this fact would be brought out on test.
If the push button is tapped into the wires running to
the bell, any break at the binding posts or between
them and the point where the button is tapped in
would not be discovered by the test.
A testing device giving a record of the test on a paper
dial is very desirable. A small tester, made on the same
principle as the test clock for thermostat systems, was
formerly made for this purpose but so far as is known there
is nothing on the market today suitable for this purpose.
It might be possible to use a small magneto actuated
by the rotary gong instead of batteries for supplying
current to ring bells, thus doing away with one of the
most frequent causes of trouble.
When a closed outside circuit is used, the wires are
always in test and it is not, therefore, necessary to make
frequent tests of the electrical features.
The best way to make a complete test is to open the
small (usually half-inch) test pipe at the top of the
sprinkler system. If this is properly installed t should
give a flow, when wide open, approximately equal to
the discharge from one sprinkler head, and this is the
minimum flow at which an alarm valve can be expected
ALARM VALVES 149
Defects. The principal defect in alarm valves today
is the liability to false alarms. A modern valve prop-
erly installed should give but little trouble but if not
installed strictly according to rules, trouble may be
expected. This trouble is often overcome by main-
taining an excess pressure in the system above the alarm
valve. There is no great objection to doing this except
that it causes extra work and if carried to an extreme
may tend to cause the valve to stick. It also makes the
valve slower in operation as the excess pressure must
drop to normal before the main check will open. In
plants where this is done the Assured usually do not
test the system as often as it should be tested and also
object to tests being made by insurance inspectors.
In alarm valves containing soft rubber facings the
rubber ring should be replaced every few years and per-
haps oftener where the pressure is very heavy.
While the record of alarm valves is not very satisfactory
so far as false alarms is concerned, and while they are
frequently found out of order on inspection, their fire
record has certainly been good. The statistics of the
National Fire Protection Association for 22 years cov-
ering various forms of alarm service are as follows:
Thermostats alone 230 48 21