An Automatic Air Pressure Alarm for use with Forced and Exhaust Draught Furnaces.
Year: 1899

page_text: Date of Application, 23rd Nev., 1899
Complete Specification Left, 28th June, 1900-Accepted, 18th Aug., 1900
PROVISIONAL SPECIFICATION.
An Automatic Air Pressure Alarm for use with Forced and Exhaust
Draught Furnaces.
JOHN HENRY SILLEY, 18, St. Andrew's Road, Plaistow, London, Marine
Engineer, do hereby declare the nature of this invention to be as follows:-
An automatic arrangement when working with forced or induced draught in
boilers or such like by which on the pressure of air in fan casing or passages
rising beyond a desired limit, this pressure will lift a disc valve or valves allow-
ing the air to escape and blow a whistle or similiar instrument which will give
warning that the maximum desired pressure is being exceeded, or equivalently
I may arrange the device so that the pressure may actuate a piston and small
rod connected thereto, which will establish contact between two wires thereby
causing an electric bell to ring.
This arrangement can be regulated to suit any pressure by adding additional
load to the valve or piston as the case may be.
1000
An Automatic Air Pressure Alarm for use with Forced and Exhaust
Draught Furnaces.
I, JOHN HENRY SILLEY, of 18, St. Andrew's Road, Plaistow, in the County of
Essex, Marine Engineer, do hereby declare the nature of this invention and in
what manner the same is to be performed to be particularly described and ascer-
tained in and by the following statement:-
This invention relates to means for operating an alarm in connection with
air pressure used in forced and exhaust draught furnaces and has for its object
the provision of a device which will readily afford an indication to the chief
engineer or other officer when any predetermined pressure has been recorded
at a position away from the boiler or stokehold or otherwise.
A very serious waste of fuel occurs when furnaces are worked at a greater
air pressure than is found by practice to be economical and very great difficulty
is experienced in checking such air pressure especially as in the case of steam
ships of the mercantile where full power working is continuous through long
periods and is controlled by or is dependent on three or more gangs of men
forming the various watches.
This invention consists in the arrangement of a device actuated by air pressure

page_text: against a resistance of a predetermined value and adapted when so operated to
actuate an alarm such as a whistle, bell or other signal, which can be situated
near to or away from the device.
In order that the invention may be the better understood I will now proceed to
describe the same in relation to the accompanying drawings, reference being had
to the letters and figures marked thereon.
Figure 1 is a diagrammatic view of an apparatus according to my invention
in which a whistle is used as the alarm.
Figure 2 is a modified arrangement of the same.
Figure 3 shows the arrangement in which an electric bell is used as an alarm.
Figure 4 is a modified arrangement of the control device, connected to an
electric bell.
..\/.
Figure 5 is a further modification.
18.
Figure 6 shows one form of the control device adapted for use with induced
or exhaust draught.
Figure 7 is a plan of one of the weights shown in the devices illustrated in
Figure 3, 5 and 6, which have a radial, slot and central hole permitting them to
be placed on the piston rod at the reduced neck provided for the purpose.
Referring to Figure 1A is a chamber having a flange B or other equivalent
means for attaching it to the bulkhead or other support in the chamber under
forced draught; at the upper part a valve seat C is arranged, upon which is placed
a valve D which may of itself be the proper weight for the particular air pressure
or may be loaded with one or more weights E, preferably in the form of discs.
A pipe leads from the space above the valve 1 to a whistle or other acoustic
signalling device. A detachable cover F¹ is provided to enable the weight E
to be adjusted.
In Figure 2 the valve D is in the form of a piston and is adapted to slide
in the cylindrical bore of the chamber so that when in the upper position the
pipe F is in communication with the air pressure.
In Figure 3 the piston F carries a piston rod G, at the upper end of which
a contact piece H is mounted which is adapted to make connection with two
electrical contacts from which wires are led to an electric battery M and bell M¹.
In Figure 4 the moving piston or valve is substituted by a bellows J which
carries the movable electrical contact maker, a spiral spring ₺ being used in place
of the weights E.
The tension of the spring L can be adjusted by screwing the casing more or
less upon the screwed support to more or less compress the said spring.
In Figure 5 the bellows is substituted by a flexible diaphragm K carrying
the contact maker, a perforated supporting plate K being provided to support
the diaphragm.
In Figure 6 the piston and outlet chamber are reversed in position to suit
the conditions existing with induced or exhaust draught as distinguished from
forced draught.
In this case the atmospheric pressure lifts the piston by reason of the partial
vacuum on the upper side. It is obvious that this arrangement can be readily
embodied in each of the other cases described and illustrated.
In Figures 3, 4, 5 and 6, the cap N carrying the electrical connections is adapted
to be detachable and is fitted with a bayonet joint fastening, so that the cap can
be removed in order to adjust the weights upon the control device.
In each of the arrangements of my invention described and illustrated, the
function is the same, viz. that nothing occurs until the desired maximum
air pressure has been exceeded. When this takes place the air pressure over-
comes the predetermined resistance and the whistle, electric bell, or other sig-
nalling device is operated. Although the devices could be made to suit any
desired pressure of air without adjustment, I prefer to make them for a minimum
pressure of air and provide adjustable means such as weights E or a spring L
for giving the necessary additional resistance for the higher pressure.

page_text: Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what
I claim is:-
ist. An automatic air pressure alarm for use with forced and exhaust draught
furnaces consisting of a chamber adapted with means for communication with
the space within which the excessive air pressure is to be indicated and provided
with a device permitting automatically on excess of pressure the volume of the
said chamber to be varied, means forming a predetermined resistance to such
increase of volume, and a signalling device adapted to be operated when the
volume of the chamber is varied by the device in the said chamber, substantially
as described.
2nd. An automatic air pressure alarm for use with forced and exhaust draught
furnaces arranged and constructed substantially as described and illustrated in
either of the forms shown in Figures 1, 2, 3, 4, 5 and 6 of the accompanying
drawings.
Dated this 28th day of June 1.
FELL & JAMES,
1, Queen Victoria Street, London, E.C.,
Agents for the Applicant.