AN IMPROVED APPARATUS FOR INDICATING LOW WATER & HIGH PRESSURE : IN STEAM BOILERS
Year: 1884

page_text: I HARRY WILKINSON of 4 Saint Aubin Villas Stamford Hill in the County of
Middlesex Mechanical Engineer do hereby declare the nature of my invention
for AN IMPROVED APPARATUS FOR INDICATING LOW WATER & HIGH PRESSURE :
IN STEAM BOILERS to be as follows:-
My invention is for the purpose of giving an audible & visible indication if the
water in a Steam Boiler should fall below a predetermined level, preferably fixed.
a little higher than the point of actual danger, and also an audible and visible
indication of the fact of the steam pressure rising above a predetermined pressure.
It is constructed in the following manner :-I employ an outer tube of wrought
iron, or other suitable material, which extends from the predetermined low water
level upwards to a convenient height, This outer tube is open at the bottom to
the water in the boiler, and also to the steam pressure; at its upper end it
terminates in an enclosed head or chamber: inside the outer tube I insert an
inner tube or rod of a different kind of metal to the outer tube, and having a
different rate of expansion when heated. The bottom of the inner tube is securely
fixed to the outer tube.
In its normal condition the bottom of the outer tube-being below the working
level of the water in the boiler-the steam pressure forces the water into it &
fills it. As the whole, or a greater portion of the outer tube is exposed to the
atmosphere, and, as it is too small to allow of any active circulation of the water
when filled, the water in the part exposed to the atmosphere is much colder than
the water in the boiler. This being the case, the free upper end of the inner tube
or rod, has a definite position in relation to the outer tube. Should the water
level in the boiler be allowed to fall below the predetermined level of the lower
end of the outer tube, the water in the tube falls into the boiler, & is replaced with
steam, which being of a higher temperature than the water which the outer tube
previously contained there is an immediate alteration in the relative positions of
the upper ends of the outer & inner tubes, due to the increased temperature, and
to their different rates of expansion.
The relative movement of the inner tube or rod is caused to actuate a suitable
mechanism contained in the above mentioned head or chamber, where it is made
to complete an electric circuit (from a battery or other suitable source) and thereby
.'

page_text: operating an electric bell and a suitable indicator, shewing it to be due to low
water. The bell and indicator being placed in a suitable position, either near to,
or at a distance from the boiler.
I may also attach to the above mentioned head or chamber, a flexible diaphragm,
a "Bourdon" tube or other device for obtaining a definite movement from varying
pressures, and cause them to actuate a suitable mechanical arrangement for
completing an electric circuit, which also rings the bell & operates the indicator
for high pressure. I provide suitable arrangements for adjusting all parts.
Connected with the apparatus, I provide a small pipe communicating between
the upper part of the apparatus and the steam space of the boiler, and having on
the pipe a cock or valve which normally is kept closed, On opening this cock
or valve, steam replaces the water in the tubes, and shews if the apparatus is in
proper working order for indicating low water.
00
1
1004

page_text: HARRY WILKINSON St Aubin Villas, The Crescent Stamford Hill, London N
in the County of Middlesex Mechanical Engineer do hereby declare the nature
of my invention for AN IMPROVED APPARATUS FOR INDICATING LOW WATER
& HIGH PRESSURE IN STEAM BOILERS and in what manner the same is to
be performed, to be particularly described and ascertained in and by the following
statement :-
The apparatus is constructed as shown in the accompanying sheet of drawings
in which Fig 1. is a complete sectional elevation of the apparatus as it would be
connected to the front of a Horizontal Boiler or to the side of a Vertical Boiler.
Fig: 2 is an illustration partly in section and partly in elevation shewing how it
would be applied if fixed upon the top of a Horizontal or Vertical Boiler. In these
views like letters refer to like parts.
It is constructed in the following manner:-I employ an outer tube A of
wrought Iron or other suitable material, which extends from the predetermined
low water level B upwards to a convenient height outside the Boiler. This outer
tube A is open at the bottom to the water in the Boiler (or other vessel) and also
to the steam pressure. At its upper end C it terminates in an enclosed head or
chamber D. Inside the outer tube A I insert an inner tube E (or rod) of a different
metal to the outer tube A, and having a different rate of expansion with varying
temperatures.
The bottom of the inner tube E is fixed to the outer tube A at the point F.
In its normal condition the outer tube A being below the ordinary working water
level G in the Boiler (or other vessel) the steam pressure forces the water up the
tubes A and E and fills them. As the greater portion of the outer tube A is
exposed to the atmosphere, and, as is is too small to allow of any active circulation
in it when filled the part exposed to the atmosphere becomes much colder than the
water in the Boiler. This being the case the free upper end of the inner tube E
assumes a definite position in relation to the upper end of the outer tube A, and
the relative positions are maintained until the water in the Boiler falls below the
level of the bottom of the tube A which has been fixed at the predetermined level
of safety. If however, the water in the Boiler should fall below this predetermined
level, the water in the tube A and E will fall into the Boiler and be replaced with
steam, which being of a higher temperature than the water which they previously
contained, there is an immediate alteration in the relative positions of the upper
ends of the outer and inner tubes A and E due to their increased temperatures and
to their different rates of expansion.
This relative movement of the inner tube (or rod) E is transmitted through
the levers H and I and causes the lever I to make Electrical contact with the
adjustable screw J, and in so doing completes an Electric circuit through the
wires K and L.
I include in this circuit any suitable source of Electro-Motive force, which in its
passage may be employed in ringing a Bell or other audible mechanism fixed in
any desirable position, and also move a visible Indicator, which will shew that
the water level in the Boiler is below the position of safety. This arrangement of
Battery, Bell, and Indicator, may be of any suitable well known principle.
In combination with the above mentioned parts I may employ suitable means
for Indicating any excess of a predetermined maximum pressure.
Such an
arrangement is shown in drawing Fig: 1 and is operated in the following
manner.
A corrugated disc M by means of the lever N is caused to make contact with
the adjustable screw and by means of wires P and L (or other return wires if

page_text: found desirable) forms an Electrical Circuit which also makes an audible and
visible Indication of High Pressure. The Bell and Indicator may be placed in any
desired position, near to, or far away from the Boiler. In place of the flexible
diaphragm M I may employ a "Bourdon Tube or other device for actuating the
Bell and Indicator for High pressure.
"3
Connected with my apparatus I provide a small pipe Q communicating between
the upper part of the apparatus and the steam space of the Boiler and having in
the pipe a Cock or Valve R which normally is kept closed, but may be opened at
any time. On opening the Cock or Valve the water in the tubes A and E is caused
to fall to the level of the water in the Boiler, and steam takes its place, and
indicates if the apparatus is in order for indicating Low Water.
.
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
1st The Employment of two Metallic tubes having different rates of expansion
when heated, placed one inside the other, or adjacent to one another, arranged
substantially as described and illustrated in the accompanying drawings, for
completing an Electric circuit for the purpose of giving audible and visible
indications of Low Water in a Steam Boiler or similar vessel.
2nd The employment of two Metallic tubes having different rates of expansion
when heated, placed one inside the other, or adjacent to one another, and arranged
substantially as described, and illustrated in accompanying drawings for the combined
purpose of giving an audible and visible indication of Low Water, and an audible
and visible indication of High pressure in a Steam Boiler or other vessel..
3rd The combination of an Electric alarm for Low Water or High Pressure of
Steam with a trial Valve or Cock and connection, for the purpose of testing its
state of working efficiency as described and illustrated.
Dated this twenty second day of October 1884.