Improvements in Low Water Alarm Apparatus and Appliances for Steam Boilers.
Year: 1889

page_text: Date of Application, 8th Feb., 1889
Complete Specification Left, 8th Nov., 1889-Accepted, 14th Dec., 1889
PROVISIONAL SPECIFICATION.
Improvements in Low Water Alarm Apparatus and Appliances for
Steam Boilers.
I. JOHN HENRY DEWHURST, of Moss Bay, Workington, in the County of
Cumberland, Mechanical Engineer, do hereby declare the nature of my said Invention
for "IMPROVEMENTS IN LOW WATER ALARM APPARATUS AND APPLIANCES, FOR
STEAM BOLLERS" to be as follows:-
This Invention is an improvement upon my two previous Inventions for Low
Water Alarm Apparatus for Steam Boilers, the first of which was patented A.D.
1884, and Numbered 6802, and the second of which was patented A.D). 1886, and
Numbered 3680.
The object of iny present Invention is to modify the general arrangement and
construction and to lessen the cost, rather than introducing any fresh elements as to
the principle of its action.
I effect these improvements by enclosing the expansion tube within a single
metallic casing of circular or other suitable form, this casing I attach to the shell of
the boiler, or to a suitable mounting connected therewith, in a manner somewhat
similar to that described in the Specifications of my previous Inventions already
referred to, but in my improved arrangement, instead of placing the whistle valve in
the casing outside the boiler, I place it at the lower extremity of the casing within
the shell of the boiler, or within the mounting by means of which the apparatus is
attached to the boiler. The seating of the valve being placed or formed on the
underside of the casing, the valve itself opens downwards and is attached to or forms
part of the expansion tube. The expansion tube is screwed through the upper or
outer end of the metallic casing, or it is passed through and then secured by lock nuts
or other equivalent means, and this outer end of the expansion tube is fitted with a
pet tap or cock by means of which it may be opened or closed as required for the
purposes hereinafter explained.
The expansion tube, as in my previous Inventions, passes in a vertical line from the
top of the metallic casing down to the low water level of the boiler, its diameter being
smaller than the diameter of the valve seat, to allow of the passage of steam between
the expansion tube upwards into a whistle case, which is formed in the outer metallic
casing and fitted with a suitable whistle.
The valve may be made like a ferrule or ring, to be passed over and secured or
otherwise fastened on the outside of the expansion tube or it may be made like a
screw coupling or union, by means of which the expansion tube formed in two lengths
may be jointed or united.
When the apparatus herein described is prepared for use, the expansion tube is
adjusted in length by means of the screw or nuts in the top of the casing until the
annular valve is brought close and tight on to the seat at the lower extremity of the
casing, and when so adjusted and placed in position on a boiler the action is as
follows, viz. :
So long as the water in the boiler is of a sufficient height to cover the end of the
expansion tube, the steam pressure forces the water up into the entire length of the
expansion tube, and the water so forced into the portion of the tube outside the boiler
becomes rapidly cooled when the expansion pipe may then be said to attain its
normal length, when however the water in the boiler sinks lower than the bottom end
of the expansion tube, then steam rushes into the tube which on becoming heated
expands in length to a sufficient extent to open the valve on the underside of the

page_text: casing, the steam then rushes through the orifice into the whistlo casing and the
whistlo is immediatly sounded and will continue to sound until the water in the boiler
is raised to a sufficient height to cover the lower end of the expansion tube, which
will then be again filled with water and on the water cooling the expansion tube will
contract to its normal length and close the valve.
The pet cock at the top of the expansion tube previously described is for testing the
action of the apparatus with the water in the boiler at the ordinary working level, as
on opening the cock and allowing the cooled water to be ejected by the pressure of
steam within the boiler and by this means a stream of hot water being allowed to flow
through the expansion pipe the latter will expand and open the valve in the same
manner as that already described when steam only is admitted.
Although a variety of metals or their alloys may be employed in the construction
of the various parts of my Improved Apparatus, it is essential that the expansion tube
should be constructed of a metal or alloy which is a better conductor of heat and will
expand at a given temperature, to a greater extent than the metal of which the outer
casing is me, for example. A copper expansion tube may be employed in com-
bination with a Cast Iron outer casing; the lower end of the outer casing may be
constructed in brass which might be more convenient in practice for the formation of
the valve seat than by forming the valve sent in cast iron casing by means of a bush
or otherwise brass would also be better adapted for forming the attachment and
connection on and through the boiler shell.
The outer easing of the apparatus would be provided with suitable openings for the
free circulation of the outer air round about the expansion tube for the purposes
previously indicated.
Detal this 21-4 t
R. HEBER RADFORD,
Agent for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Low Water Alarm Apparatus and Appliances for
Steam Boilers.
1, JOHN HENRY DEWHURST of Moss Bay, Workington, in the County of
Cumberland, Mechanical Engineer, do hereby declare the nature of my said
Invention for "IMPROVEMENTS IN LOW WATER ALARM APPARATUS AND APPLIANCES,
FOR STEAM BOILERS," and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement :-
This Invention is an improvement upon my two previous Inventions for Low
Water Alarm Apparatus for Steam Boilers, the first of which was patented A.D. 1884
and Numbered 6802, and the second of which was patented A.D. 1886 and Numbered
3680.
The object of my present Invention is to modify the general arrangement and
construction and to lessen the cost, rather than introducing any fresh eleinents as to
the principle of its nction.
effect these improvements by enclosing the expansion tube within a singlo
metallic casing of circular or other suitable form, this casing 1 attach to the shell of
the boiler or to a suitable mounting connected therewith, in a manner somewhat
similar to that described in the Specifications of my previous Inventions, already
referred to, but in my improved arrangement instead of placing the whistle valve in
the upper part of the casing outside the boiler I place it at the lower extremity of the
casing within the shell of the boiler or within the mounting, by means of which the
apparatus is attached to the boiler. The seating of the valve being placed or formed
on the underside of the casing, the valve itself opens downwards and is attached to or
forms part of the expansion tube. The expansion tube is scrowed through the upper
or outer end of the metallic casing or it is passed through and then secured by lock

page_text: nuts or other equivalent means, and this outer end of the expansion tube is fitted with
a pet tap or cock by means of which it may be opened or closed as required for the
purposes hereinafter explained.
The expansion tube as in my previous Inventions passes in a vertical line from the
top of the metallic casing, down to the low water level of the boiler, its diameter being
smaller than the diameter of the valve seat to allow of the passage of steam between
the expansion tube upwards into a whistle case which is formed in the outer metallic
casing and fitted with a suitable whistle.
The valve may be made like a ferrule to be passed over and screwed or otherwise.
fastened on the outside of the expansion tube or it may be made like a screw coupling
or union by means of which the expansion tube formed in two lengths may be joined
or united.
When the apparatus herein described is prepared for use the expansion tube is
adjusted in length by means of the screw or nuts in the top of the casing until the
annular valve is brought close and tight on to the seat at the lower extremity of the
casing and when 50 adjusted and placed in position on a boiler the action is as
follows, viz. :
So long as the water in the boiler is of a sufficient height to cover the end of the
expansion tube, the steam pressure forces the water up into the entire length of the
expansion tube and the water so forced into the portion of the tube outside the boiler
becomes rapidly cooled, when the expansion pipe may then be said to attain its
normal length, when however the water in the boiler sinks lower than the bottom end
of the expansion tube, then, steam rushes into the tube, which on becoming heated
expands, in length to a sufficient extent to open the valve on the underside of the
casing the steam then rushes through the orifice into the whistle casing and the
whistle is immediately sounded and will continue to sound until the water in
the boiler is raised to a sufficient height to cover the lower end of the expansion tube,
which will then be again filled with water and on the water cooling the expansion
tube will contract to its normal length and close the valve.
The pet cock at the top of the expansion tube previously described is for testing the
nction of the apparatus with the water in the boiler at the ordinary working level, as
on opening the cock and allowing the cooled water to be ejected by the pressure of
steam within the boiler, a stream of hot water is allowed to flow through the
expansion pipe, the latter will then expand and open the valve in the same manner as
that already described when steam only is admitted.
Although a variety of metals or their alloys may be enployed in the construction of
the various parts of my Improved Apparatus, it is essential that the expansion tube
should be constructed of a metal or alloy which is a better conductor of heat and will
expand, at a given temperature, to a greater extent than the metal of which the outer
casing is made, for example a copper expansion tube may be employed in combination
with a Cast Iron outer casing, the lower end of the outer casing may be constructed
in brass which might be more convenient in practice for the formation of the valve
seat, than by forming the valve seat in the cast iron casing by means of a bush or
otherwise; brass would also be better adapted by forming the attachment and
connection on and through the boiler shell.
The outer casing of the apparatus would be provided with suitable openings for the
free circulation of the outer air round about the expansion tube for the purposes
previously indicated.
The nature of my Invention may be better understood on reference to the
accompanying sheet of drawings in which,
Fig. 1, is a sectional elevation of my further improved and modified Low Water
Alarm Apparatus, shewing the whistle valve within the shell of the boiler placed at
the lower extremity of the casing or mounting by means of which the apparatus is
attached to the boiler.
Fig. 2. is a sectional elevation of my further improved and modified Low Water
Alarm Apparatus shewing the alternative method of placing the whistle valve at the

page_text: lower extremity of the casing within or inside the mounting by means of when
apparatus is attached to the hoiler.
Fig. 3. being an exterior elevation of Fig. 2. the shell of the boiler being in
section.
Figs. 4, and 5, represent a section and exterior view of the alternative method of
attaching the whistle valve to the expansion tubo by means of which the expansion
tube may be made in one length.
The same letters of reference are used to mark similar parts throughout the soveral
views.
a, is the expansion tube.
b, is the single metallic casing
is the shell of the boiler.
the same.
d, is the mounting by means of which the casing b, is attached to the shell of the
boiler c.
is the whistle valve and
is the sent for the same.
9, 9, are the lock nuts by means of which the expansion tube is secured to the
upper end of the casing.
, is the pet tap or cock for testing the apparatus.
i, is the whistle case.
is the whistle attached to the same.
k, k, is the orifice or orifices through which the steam is conveyed from the boiler
to the whistle case.
1,1,1, are openings in the outer case for the free circulation of air round the
expansion tube.
m, is a lock nut for securing the whistle valve to the expansion tube by the
alternative method which may be used or not as required.
n, is the lock nut by means of which the mounting d, is secured to the boiler
shell.
Having now particnlarly described and ascertained the nature of my Inven-
tion and in what manner the same is to be performed I declare thai what I
claim is,
1. In an Automatic Low Water Alarm Apparatus as herein described, the
combination of parts and appliances in the general arrangement and construction,
comprising
(a.) Placing the whistle and whistle case at the lower end of the vertical case
surrounding the expansion tube as illustrated in Figs. 1, 2 and 3.
(b.) Placing the whistle valve and seat inside the boiler at the lower extremity
of said cise or at the lower extremity of a suitable mounting, by means of
which the said case is secured to the shell of the boiler as illustrated in
Fig. 1.
(a) Attaching the whistle valvo to the expansion tube, the expansion tube being
in two lengths as shewn in Figs. 1, 2 and 3.
(d.) Attaching a pet or test cook at the top of the expansion tube as shown in
Figs. 1, 2 and 3.
2. In a similar combination of parts and appliances in lieu of placing the whistle
valvo and seat inside the boiler as described in claim 1 (b.) the alternative arrange-
ment of placing the whistle valve and seat at the lower extremity of said case within
or inside of the mounting by means of which the said case is attached to the shell of
the Boiler as illustrated in Figs. 2 and 3.
3. In a similar combination of parts and appliances in lieu of attaching the whistle
valve to the expansion tube as described in claim 1 (c.) the alternative method of
attaching the whistle valve to the expansion tubo, the expansion tube being in one
length as shewn in Figs. 4 and 5.
The respective combinations of parts and appliances constituting the further

page_text: improvements and modifications in the general arrangement and construction of my
"Low Water Alarm Apparatus and Appliances for Steam Boilers," substantially as
herein described and illustrated in Figs. 1, 2, 3, 4 and 5 on the accompanying sheet
of drawings.
Dad thin eth J. 1980
R. HEBER RADFORD,
Agent for the Applicant.