Year: 1885

page_text: 11
DOROT DOW water Alarms.
I, OLIVER IMRAY of No 28 Southampton Buildings, Chancery Lane in the
County of Middlesex, Fellow of the Institute of Patent Agents, 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:—
This invention relates to a construction and arrangement of an automatic
alarum for steam boilers which, when the level of water in the boiler is too low,
causes a whistle or the like to sound, calling attention to the fact.
In the accompanying drawings Fig. 1 is an elevation, and Fig. 2 is a vertical
central section, partly in elevation, of apparatus according to this invention;
Fig. 3 is a sectional plan on line ; Figs. 4 and 5 shew two positions of the
valve N¹ at high and low level of water respectively; Fig. 6 is a section on line y
Fig. 4.
A is part of the shell of a steam boiler, B is a cylinder or water column such as
is often used to receive the glass gauge and gauge cocks to avoid weakening the
shell A by the holes for the gauge and gauge cocks. E is a glass gauge of ordinary
construction. The cap C of the column has a boss F with a passage G through it
screwed to receive a whistle or other similar sounding instrument H at its top,
and a valve seat I at its bottom. K is a cock for blowing off sediment. L is a
cylindrical float having extending up from it a valve N¹ seating on I. The stem N
of the valve is, as shewn in Fig. 6, triangular in cross-section; so that steam can
pass, when the valve N¹ is withdrawn from its seat, through the passage G to the
whistle H.
The lower end of the float L is provided with a shoulder O and a spindle O¹,
passing through a guide 0, so that while the float L is held upright, it is free
to move up and down by the varying height of the level of the water in the
cylinder B.
Within the float a small chamber P is formed as shewn; this chamber is open to
the pressure within the cylinder B, by means of openings R, causing the float to be

page_text: much more sensitive to the changes of level of water than the float would be
without the chamber, and this is an important feature in the invention.
When the valve N¹ is seated as shewn in Fig. 2, it closes the passage in I,
preventing the whistle from sounding and, but for a provision about to be
described, it would be held in that position by the pressure of the steam, until
the level of the water falls a considerable distance; so much would this affect the
float of the small size that can be placed within the cylinder B, that it would
render it useless. By actual test the inventor has found that when the float is
provided with the chamber P and openings R, it is rendered sufficiently accurate
in its action.
If the line 1 indicates the proper level of the water in the boiler, and the line 2
that at which the alarm should sound when the boiler requires more water, then it
will be found that the float provided with chamber P and openings R, will descend
from the position shewn in Fig. 2, as soon as the level of the water falls to the
line 2 until its shoulder O rests upon the guide 02. This brings the valve N¹ to
the position shewn in Fig. 5, where it will remain until the level of the water is
raised in the boiler and cylinder B, whereupon the valve N¹ is again raised to the
position shewn in Figs. 2 and 4.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is
1. In a low water alarm for a steam boiler, a float arranged as described and
provided with an upper chamber open to the pressure in the space containing the
float and also provided with a valve, in combination with a cylinder or water
column having a valve seat passage, and a sounding device substantially as
described.
2. The combination of the cylinder B having valve seat I and sounding device H,
connected therewith as shewn and described, with a float L, having chamber P,
open to the pressure within the cylinder B, the whole substantially as described.
Dated this 30th day of December 1885.