Improvements in Low-water Alarms for Steam Boilers.
Year: 1890

page_text: Date of Application, 6th Nov., 1890-Accepted. 6th Dec.
4800
COMPLETE SPECIFICATION.
Improvements in Low-water Alarms for Steam Boilers.
I EZEKIEL GRAYSON CONSTANTINE of 32 Victoria Street Manchester in the County
of Lancaster, Consulting Engineer do hereby declare the nature of this invention and
in what manner the same is to be performed to be particularly described and
ascertained in and by the following statement and accompanying drawings
:-
My said invention relates to improvements in apparatus for automatically sounding
an alarm when the level of the water in a steam boiler has sunk below a certain pre-
determine point. hereinafter referred to as the low water level and especially to that type
of low water alarm which in its essential features consists of a pipe open at its lower
end to the interior of the boiler below the low water level and provided at its upper
end with a whistle or steam roarer. A considerable length of the said pipe is exposed
to the cooling action of the atmosphere so that the water which is forced therein by
the pressure of the steam is kept cooler than the water in the boiler.
of the said type there is usually a piece of metal hereinafter referred to as the fusible
In apparatus
plug inserted in the pipe at some point below the whistle so that on the water in the
boiler sinking below the low water level the water in the tube will run back into the
boiler and be replaced by the hot steam which will then melt the plug and blow
the whistle. It is in such case understood that the plug must be composed of such
an alloy as will readily melt at the temperature of the steam issuing from the boiler
but which will nevertheless remain solid at the temperature of the water in the
tube.
I make no claim to the general principle of a low water alarm constructed so as to
act in the aforesaid manner. My said invention relates solely to improvements in
the construction thereof and has for its object to effect a more ready means of
replacing the plug when melted, of ascertaining whether the apparatus is in proper
working order, and of removing dirt or other obstacle to its perfect action as well as
generally to increase its efficiency.
In order that my said invention may be more fully understood I will proceed to
describe the same with reference to the accompanying drawings.
Fig. 1 is a sectional elevation of a low water alarm constructed according to my inven-
tion. a is a steam whistle or roarer connected by a pipe 6 with the interior of the plug
chamber closed by a screw cap d. The fusible plug is shown at e and is held in
position on its seating by a screw cap provided with one or more apertures for the
passage of steam. I prefer to form and distribute these apertures in such a manner
s to be adapted to receive the points of a screw-key inserted through the hole in the
op of the chamber e for the purpose of rotating the screw cap. The seating g of
he fusible plug is provided with an annular channel as shown in the drawing for
he purpose of receiving part of the molten alloy when the plug melts. hh is a
ube opening at 2 to the interior of the boiler below the low water level. k represents
vertical section of the shell of the boiler to which the whole apparatus is secured by
screw coupling as is well understood. At a suitable point in the passage between
he fusible plug e and the interior of the boiler I insert a three-way cock / having
s passages formed in such a manner as that firstly when the plug is set in the
osition shown in the drawing there is an uninterrupted passage between the fusible
ug e and the interior of the boiler, secondly when the plug is turned quarter round
one direction the said passage is entirely close and neither water nor steam can
ach the fusible plug e from the interior of the boiler, thirdly when turned a quarter
und in the other direction the passage between the fusible plug e and the interior
the boiler is still closed while a connection is established between the interior of
e boiler and the lateral bib m se Fig. 2 which represents a side elevation of the
ree-way cock 1. The passages in the plug of the three-way cock consist of one

page_text: hole right through the plug as shown in Fig. 1 and of a hole at right angles thereto
but only reaching from the outside of the plug to the centre as indicated by
dotted lines.
provided
on
The plug of the three way cock is turned by a lever or handle
with means such as a hole for securing it by a lock or seal to a bracket
the pipe h.
When the three way cock is turned so as to cut off communication with the
interior of the boiler the fusible plug e may be easily examined and replaced when
necessary without letting off the pressure of the steam in the boiler. When a
passage is opened from the interior of the boiler to the bib m the attendant can
easily ascertain by the egress of water whether the passage is clear and any air
which may be in the pipe can also be driven out through the bib m.
For facilitating the removal of dirt or other obstacle to the free entrance of
steam or water to the pipe I provide a screw plug n which can be readily
removed for the purpose of inserting a wire or rod into the pipe h'.
1 may screw the whistle a direct into the top of the plug chamber and thus
dispense with a separate cap d in which case the whistle itself would have to be
removed to enable the plug to be changed.
Instead of securing the apparatus to a vertical side of the boiler I may employ in
some cases a vertical standard pipe 3 Fig. 3 in place of the tube h, the said standard
pipe being secured to a horizontal part of the shell of the boiler k¹ by a screw
coupling. A continuation pipe h is secured to the standard pipe and descends
below the low water level.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is:
1. In a low water alarm for steam boilers operated by the fusion of a plug the
combination of the plug chamber c, the screw cap, the channelled seating 9, the
three-way cock and the screw plug n substantially as and for the purpose herein-
before described and set forth.
2. In a low water alarm for steam boilers acting on the fusion of a plug the means
for securing the fusible plug consisting of a screw cap e in combination with the plug
seating 9 substantially as and for the purpose herein before set forth.
3. In a low water alarm acting on the fusion of plug the three-way cock 1
substantially as and for the purpose hereinbefore described and set forth.
4. In a low water alarm of the type hereinbefore described the removable screw
plug n substantially as and for the purpose herein before set forth.
Dated this Fifth day of November 1890.
EDWARD TURNER WHITELOW,
70, Deansgate, Manchester, Agent for Applicant.