IMPROVEMENTS IN ALARM APPARATUS FOR GIVING WARNING WHEN THE PRESSURE IN A STEAM BOILER ( OR VESSEL WORKING UNDER PRESSURE IS TOO HIGH OR THE WATER LEVEL TOO Low
Year: 1871

page_text: LETTERS PATENT to Joseph Kirk, of No. 11, Blossom Street, in the
City of London, for the Invention of "IMPROVEMENTS IN ALARM
APPARATUS FOR GIVING WARNING WHEN THE PRESSURE IN A STEAM BOILER
( OR VESSEL WORKING UNDER PRESSURE IS TOO HIGH OR THE WATER LEVEL
TOO Low."
Sealed the 8th August 1871, and dated the 12th May 1871.
PROVISIONAL SPECIFICATION left by the said Joseph Kirk at the
Office of the Commissioners of Patents, with his Petition, on the
12th May 1871.
t
I, JOSEPH KIRK, of No. 11, Blossom Street, in the City of London,
do hereby declare the nature of the said Invention for "IMPROVEMENTS
IN ALARM APPARATUS FOR GIVING WARNING WHEN THE PRESSURE IN A STEAM
BOILER OR VESSEL WORKING UNDER PRESSURE IS TOO HIGH OR THE WATER LEVEL
Too Low," to be as follows:-
:-
This Invention has for its object improvements in alarm apparatus
for giving warning when the pressure in a steam boiler or vessel
working under pressure is too high or the water level too low.
:

page_text: The apparatus is composed of a metallic vessel containing a fluid of
known expansive properties under heat, by preference mercury. This
vessel is surrounded by a casing, which when the apparatus is to be
used as a low water indicator is connected by a pipe leading from its
bottom to the steam boiler below the proper working level of the water.
In the vessel containing the mercury is a float, and on the upper end of
the float are fixed two valves, one above the other. The seating for the
lower valve is upon the upper end of the vessel containing the mercury.
The seating of the upper valve is carried by the casing or jacket. On
the top of the casing and above the upper valve is placed a whistle.
The mercury in the vessel is.adjusted to raise the valves by its increase
in volume should the temperature exceed a given limit. Whenever the
water in the boiler descends below the level of the pipe which leads from
the boiler to the alarm apparatus this pipe becomes filled with steam;
the volume of the mercury is then increased, and the valves carried by
the float are raised, and steam is free to pass the upper valve and the
whistle is sounded.
If the apparatus is to be employed for giving warning when the
pressure in a boiler is too high the pipe leading to the alarm
apparatus leads out from the steam space of the boiler, and the mercury
is adjusted to raise the float when the temperature of the steam is too
great.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Joseph Kirk in the Great Seal Patent Office on
the 10th November 1871.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOSEPH'
KIRK, of No. 11, Blossom Street, in the City of London, send greeting. 3
WHEREAS Her most Excellent Majesty Queen Victoria, by Her.
Letters Patent, bearing date the Twelfth day of May, in the year of our
Lord One thousand eight hundred and seventy-one, in the thirty-fourth
year of Her reign, did, for Herself, Her heirs and successors, give and
grant unto me, the said Joseph Kirk, Her special license, that I, the 3

page_text: said Joseph Kirk, my executors, administrators, and assigns, or such
others as I, the said Joseph Kirk, my executors, administrators, and
assigns, should at any time agree with, and no others, from time to time
and at all times thereafter during the term therein expressed, should
and lawfully might make, use, exercise, and vend, within the United
Kingdom of Great Britain and Ireland, the Channel Islands, and Isle of
Man, an Invention' for "IMPROVEMENTS IN ALARM APPARATUS FOR GIVING
WARNING WHEN THE PRESSURE IN A STEAM BOILER OR VESSEL WORKING UNDER
PRESSURE IS TOO HIGH OB THE WATER LEVEL TOO Low," upon the condition
(amongst others) that I, the said Joseph Kirk, my executors or admi-
nistrators, by an instrument in writing under my, or their, or one of
their hands and seals, should particularly. describe and ascertain the
nature of the said Invention, and in what manner the same was to be
performed, and cause the same to be filed in the Great Scal Patent Office
within six calendar months next and immediately after the date of the
said Letters Patent.
NOW KNOW YE, that I, the said Joseph Kirk, do hereby declare
the nature of the said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the
following statement thereof, that is to say :-
This Invention has for its object improvements in alarm apparatus for
giving warning when the pressure in a steam boiler or vessel working
under pressure is too high or the water level too low.
•
· The apparatus consists of a vessel containing a liquid such as mercury
which will expand by heat without sensible evaporation. The vessel is
closed at the top by a valve, and on the mercury is a float which at a
certain temperature to which the apparatus is adjusted presses against
the under side of the valve. The vessel containing the mercury is
enclosed in a jacket, to which the steam or water from the boiler is
admitted. At the top of the jacket is also a valve seat and a valve.
The two valves are connected by a stem, and as they are nearly of the
same area the pressures upon them almost balance each other. The
valves are thus very easily lifted by the float. When the valves are
closed the pressure in the mercury chamber on the under side of the
valve does not exceed the pressure above the upper valve. This is
ensured by forming a small passage through the stem connecting the
two valves. A whistle is fixed on the top of the jacket over the upper
valve, and when steam passes this whistle sounds. As soon as the valve

page_text: The jacket d is closed at the top by the valve c³, which is soldered or
otherwise attached to the stem c³ of the valve c; c³ is a small perforation
through the stem of the valve. The valves are contained in the valve
chamber e, which is in direct communication with the jacket, and can be
regarded as part of it. f is a whistle immediately over the valve c³.
The pressure on the valves being nearly balanced they remain on their
seats by their own weight and also by a slight excess of pressure on the
valve c, except when the float acts upon them, but immediately they
are started by the float the steam enters the mercury chamber a more
rapidly than it can escape by the perforation c³, and the pressure which
thus accumulates in this chamber forces up the valves until the passage
is fully open for the steam to pass to the whistle.
Having thus described the nature of my said Invention, and the
manner of performing the same, I would have it understood that I
claim,―
The combination of the equilibrium valves with a mercury float or
equivalent instrument for starting them from their seats and a chamber
in which the pressure then accumulates and lifts the valves to the full
extent, substantially as described.
I also claim the construction of alarms substantially as described.
In witness whereof, I, the said Joseph Kirk, have hereunto set my
hand and seal, this Sixth day of November, in the year of our
Lord One thousand eight hundred and seventy-one.
JOSEPH KIRK. (L.S.)