70 BULLETIN SOI, U. S. DEPARTMENT OF AGEICULTUEE. 
by a water motor which operates the alarm when there is move- 
ment of water flowing through the pipes; or the alarm may be 
operated by electricity, the operation being caused by a flow of water. 
The water motor alarm is generally used for the cotton warehouse. 
There should be a separate alarm for each branch main, which usually 
means a separate alarm for each compartment, (See the discussion 
of signaling systems.) 1 
The warehouseman who is considering sprinkler equipment would 
do well to employ an engineer to handle the contract and negotiate 
with the insurance companies. The warehouseman, however, may 
be able to get information as to the cost of such equipment by apply- 
ing to the sprinkler company's engineers, but he should secure in- 
surance concessions before letting the contract in order that he may 
know what savins: and increased revenue will be affected. Some 
plants can pay for sprinkler equipment by resulting insurance sav- 
ings of a few years. 
WATER SUPPLY. 
The water supply available or which may be secured at a rea- 
sonable cost frequently limits the fire protection of small warehouses. 
Under most conditions a warehouse should not be constructed unless 
a reasonable supply of water can be provided. 
-"Water supplies are considered as "primary" and "secondary:'' 
the first being the source from which water is furnished automati- 
cally to the sprinkler or hydrant systems, while the secondary supply 
is the means for supplementing the first. The secondary supply may j 
be controlled automatically or by hand. 
The usual supply of water for the warehouse is the city main con- 
nection and a gravity tank, the tank, used as a primary supply, being 
filled from the city mains. The tank gives a constant head of 
water in case the city supply is interrupted, so it is of greatest im- j 
portance that the tank be kept full. For the warehouse plant of 
ordinary size such a supply is all that should be required provided 
the city supply itself is satisfactory. Fairly good protection is 
afforded by the city connection alone, the objection to this being ] 
that water mav be cut off at times for work on mains. 
_ 
1 The detailed requirements of the sprinkler system have been so completely 
worked out by the National Board of Fire Underwriters that it is undesirable 
to hare duplication of these specifications here. Moreover the sprinkler sys- 
tem involves the use of various valves and other equipment which must be 
tested by engineers such as the service supplied by the Underwriters^ Labora- 
tories. 
For warehouse plants maintaining a central watch station, or for other 
extensive plants, the automatic supervision service should prove of value. 
This consists of a system of electric signals which will give an alarm and 
register at the watch office any interference with valves, water supply, pressure, 
flow of water or low air pressure of the dry system. 
