IMPROVED MEANS AND APPARATUS FOR PROTECTING FEED WATER HEATERS AGAINST THE EFFECTS OF FROST
Year: 1873

page_text: PROVISIONAL SPECIFICATION left by Arthur Wallis and Charles
James Steevens at the Office of the Commissioners of Patents,
with their Petition, on the 13th March 1873.
We, ARTHUR WALLIS and CHARLES JAMES STEEVENS, both of Basing-
stoke, in the County of Southampton, Engineers and Agricultural
Implement Makers, do hereby declare the nature of the said Invention
for "IMPROVED MEANS AND APPARATUS FOR PROTECTING FEED WATER HEATERS
AGAINST THE EFFECTS OF FROST," to be as follows:
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The vessels and pipes frequently employed in heating the feed water
of steam engines before it enters the boiler are generally left charged
with water after the engine has ceased to work. When such feed water
heaters are in exposed situations, as is more particularly the case with
portable engines, the water contained in them becoming frozen tends to
burst them or to break joints, and cause leakages which are not dis-
covered till the engine is again set to work.
Our Invention relates to means of automatically emptying feed
heaters when they are not in use, or when the engines or boilers with
which they are connected cease to work, and to apparatus for that

page_text: purpose. We effect this in several ways which we will now describe.
According to one method we provide the feed heater with a discharge
cock or valve which is connected to the starting lever of the engine in
such a manner that when the said lever is moved so as to cause the
engine to work, the cock or valve is closed, and the feed heater then can 5
operate; but when the starting lever is pulled back so as to stop the
engine, the cock or valve is opened and the contents of the feed heater
are discharged.
Instead of connecting such discharge cock or valve to the starting
lever it may be connected to the governor, so that it is closed while the 1
governor revolves, but is opened by the collapsing of the governor balls
when the engines stop.
In like manner the discharge cock or valve of the feed heater may be
connected to any part of the engine, which is necessarily in a different
position when the engine stops from that which it occupies while the
engine is at work, so as to be opened in the former case, and closed in
the latter.
Or the discharge cock or valve of the feed heater may be connected to
a piston fitted in a cylinder communicating with the boiler in such a
manner that when there is a certain amount of pressure in the boiler, the
said piston is moved so as to close the cock or valve, but when the
pressure in the boiler falls below that amount, the piston is caused to
move back by a weight or spring, and the discharge cock or valvo is
opened so as to allow the contents of the feed heater to escape. Instead
of employing a separate piston thus to work the discharge of the feed
heater a valve opening inwards may be provided with a spring or weight
which causes it to open when the pressure in the boiler, and consequently
in the feed heater which communicates with it, falls below a certain
amount, the spring or weight being so adjusted that the valve is kept
closed by the pressure in the boiler or feed heater when it is at work.
Or instead of employing the movement of the engine or the boiler
pressure as the agents for closing the discharge of the feed heater, the
clevated temperature of the boiler may be employed for this purpose in
the following manner :-A long metal rod is inserted in one of the flucs
or tubes of the boiler, or placed in any position where it is exposed to
heat when the engine or boiler is at work, and is connected at one end to
the discharge cock or valve of the feed heater so as to close the said cock

page_text: or valve when the rod is expanded by heat, and to open it when the rod
contracts on the boiler flues and other parts becoming cold.
In case where the length of such pyrometric rod is limited so that
the amount of change which it undergoes owing to the change of tem-
perature is too small to give adequate movement to the cock or valve,
the latter may be fitted with a weight or spring which will open it, and
provided with a detent or trigger to keep it closed, such detent or
trigger being connected to a pyrometric rod, so that when the rod
contracts by cooling the trigger or detent is withdrawn, and the
discharge of the feed heater is opened.
Instead of a single pyrometric rod, which has a very small movement
when it undergoes change of temperature, a compound bent bar may be
used, such bar consisting of two strips of metal having different degrees
of expansibility combined together as in the compensating balances of
time-pieces. The effect of a change of temperature on such a componnd
bar is to bend it more or less, and the movement of one of its ends caused
by such change of flexure, may be employed to work the discharge of
the feed heater as above described.
Although we have referred above to the discharge cock or valve as if
it were single for the emission of water only, it is to be understood that
it should be constructed so as to also admit air to the feed heater for the
purpose of allowing the proper outflow of the water.
This may be
effected by making such discharge cock with an air port in the manner
well known in reference to syphon taps. Or there may be a separate
valve or cock for admission of air connected to that by which the water
is discharged and opened or closed with it. Or a small air valve opening
inwards may be fitted to the feed heater at a level above that of the
water discharge. This valve kept usually closed by the pressure of fluid
within the heater will open for the admission of air when the pressure is
reduced below that of the atmosphere by the opening of the discharge
cock or valve.