IMPROVEMENTS. IN THE ARRANGE- MENT OF VALVES AND APPARATUS FOR PREVENTING STEAM BOILER EXPLOSIONS
Year: 1856

page_text: LETTERS PATENT to John Knowelden, of Southwark, in the County of
Surrey, Engineer, for the Invention of "IMPROVEMENTS. IN THE ARRANGE-
MENT OF VALVES AND APPARATUS FOR PREVENTING STEAM BOILER EXPLOSIONS."
Sealed the 30th December 1856, and dated the 15th September 1856.
PROVISIONAL SPECIFICATION left by the said John Knowelden at the
Office of the Commissioners of Patents, with his Petition, on the
15th September 1856.
I, JOHN KNOWELDEN, of Southwark, in the County of Surrey, Engineer,
do hereby declare the nature of the said Invention for "IMPROVEMENTS IN
THE ARRANGEMENT OF VALVES AND APPARATUS FOR PREVENTING STEAM BOILER
EXPLOSIONS," to be as follows:-
For the purpose of preventing the risk of explosion arising from overloading
the safety valves, or from working with insufficient water in steam boilers,
I use the following arrangement, by which I prévént the possibility of
increasing the pressure of steam beyond that determined for working, and
give ready and certain notice of want of water in the boiler. Either on the
top of the boiler, or in a chamber to be fixed upon it and open to the pressure
of steam, I have two valves, one of which is arranged as an ordinary steam
valve, having the weighted lever passing over it, the other valve I joint to
the end of the said lever, of which it becomes the fulcrum. Attached to this

page_text: valve I have a small rod passing into the boiler, which is there attached to
or is in communication with a lever actuated by a float in the boiler, and so
arranged that the buoyant power of the float draws down the rod, and the
valve attached, which it keeps in position, which buoyant power of the float
is sufficient to overcome the desired working pressure of steam in the boiler
when the first-named valve is loaded by a proper weight on the lever acting
upon it. By this arrangement of apparatus, I make the first-named valve
the working one, but by the addition of the second valve, as described, it will
be seen that if any extra weight be placed upon the lever acting upon the
working valve, it will reduce so much from the buoyant power of the float,
and consequently the top of the ordinary working valve will become the
fulcrum of the lever, the valve jointed to the end of which will then become
the working one, rendering it impossible by neglect or wilfulness to overload
the valves; the whole may be securely locked up in a box or covering, the
weighted end of the lever only projecting through the same. Should the
water in the boiler fall below the proper level to which the float acting upon
the safety valve is set, the float, then losing the buoyant power of the water
by its gravity, acts upon the lever and rod attached to the valve, as before
described, and opens the same, preventing the generation of pressure by
opening the valve when an insufficient quantity of water is in the boiler. I
also adapt the following arrangement to boilers, by which means I prevent
the generation of steam after the water comes below a certain level, or the
pressure of steam in the boiler exceeds that desired. Into the bottom of the
boiler I screw or fix a tube which ends on the outside over the fire, and in
the inside of the boiler at a point below the low-water level. The end of
the tube inside is fitted with and closed by a spherical valve, which valve is
fixed to and is kept in position by a float of sufficient buoyancy to keep the
spherical valve water-tight under any ordinary working pressure. I so arrange
the valve and float that so long as sufficient water for safe working remains
in the boiler the spherical valve is kept closed, but directly the water gets
below the proper level, the float following it opens the valve, or should the
steam exceed the proper working pressure, the valve will be depressed; in
either case, the water being above the valve, rushes through it into the tube
terminating over the fire, which it extinguishes, thereby preventing further
generation of steam.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John Knowelden in the Great Seal Patent Office on the
14th March 1857.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
KNOWELDEN, of Southwark, in the County of Surrey, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fifteenth day of September, in the year of our Lord
One thousand eight hundred and fifty-six, in the twentieth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
John Knowelden, Her special licence that I, the said John Knowelden, my
executors, administrators, and assigns, or such others as I, the said John
Knowelden, my executors, administrators, and assigns, should at any time agree
with, and no others, from time to time and at all times thereafter during the
term therein expressed, should and lawfully might make, use, exercise, and
vend, within the United Kingdom of Great Britain and Ireland, the Channel
Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN THE ARRANGE-
MENT OF VALVES AND APPARATUS FOR PREVENTING STEAM BOILER EXPLOSIONS," upon
the condition (amongst others) that I, the said John Knowelden, my executors
or administrators, by an instrument in writing under my, or their, or one of
their hands and seals, should particularly describe and ascertain the nature
of the said Invention, and in what manner the same was to be performed, and
cause the same to be filed in the Great Seal Patent Office within six calendar
months next and immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said John Knowelden, do hereby declare tho
nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement (that is to say):-
For the purpose of preventing the risk of explosion arising from over-
loading the safety valves, or from working with insufficient water in steam
boilers, I adopt the following arrangements, by which I prevent the possibility
of increasing the pressure beyond that determined for working, and give
ready and certain notice of an improper supply of water in the boiler; I also
indicate the exact depth of water in the boiler, and I prevent the generation
of steam altogether when the water is below a certain level, or the pressure of
steam exceeds that desired.
And in order that my Invention may be more easily understood, I refer to
the accompanying Sheet of Drawings, with the figures and letters of reference
marked thercon.

page_text: Fig. 1 represents a section of a boiler fitted with my improved apparatus;
and Figures 2, 3, and 4 represent enlarged sections of the apparatus. On the
top of the boiler A, A, or on a chamber connected therewith, as B, I have
two valves C and D (Fig. 2); D acts as an ordinary safety valve, having the
weighted lever E passing over and pressing upon it. The valve C is connected
to the lever E by a joint, which forms a fulcrum at F, and attached to this
valve is a rod passing into the boiler, and connected with the bent lever G, H,
at G. This lever G, H, is actuated by a float at II, which is immersed in
the water, and by its buoyancy draws down the valve C. The action of this
compound safety valve is simply this:-The float II is of a size sufficient to
give a pressure by its buoyancy of rather more than twice the intended
working pressure, so that when the weight I is placed on the lever E, the
pressure on the two valves will be nearly equal, or leaving rather more
pressure on the valve C than on D. If through neglect, or any other cause,
the water in the boiler should fall below the low-water line, the float will be
unsupported and the valve C will open, and any extra weight placed on the
lever at I, for the purpose of increasing the pressure, will have the contrary
effect, as such weight will tend to raise the valve C as much as it will depress
the valve D.
I also effect a similar object by the apparatus as shewn at Fig. 3. Instead
of the valve C, as in Fig. 2, I extend the rod B', through a stuffing box or
other suitable means, and joint the said rod to the lever at F; I also add
two upright standards or fulcrums K and L. The lever E is furnished with
an indicator over the valve D. It is evident, if the float II should fall through
want of water in the boiler, the pressure at F will be liberated, and the
weight I will draw down the lever E on the fulcrum L, and so open the
valve D; and the same effect will be produced if the lever be unduly weighted
at I, so also if there be excess of water in the boiler the float II will rise,
and draw down the lever at F until it rests on the fulcrum K, and so open
the valve D, and liberate the steam. As the float rises or falls between low
and high water, it will cause the lever E to oscillate accordingly, and the
finger or indicater M will always shew the exact depth of water in the boiler,
and the weight upon the safety valve D will always be uniform, unless the
water in the boiler be too high or too low, in which case, as in that of Fig. 2,
the valve is instantly opened, timely notice is given of too high pressure or
of improper supply of water, and the bursting of the boiler prevented.
By the apparatus represented by Fig. 4, I prevent the generation of steam
when the water is below a certain level, or when the pressure of steam is too
high. I fix a tube or pipe into the bottom of the boiler, as seen at O, Figs. 1

page_text: and 4, over or extending to the fire. On the top of the tube I attach a valve
box with a spherical, hemispherical, or curved valve P, which valve is con-
nected to or suspended from a float N, which is immersed a little below the
low-water line, and is of sufficient buoyancy to overcome the desired working
pressure of steam on the valve P; should the pressure be greater than this,
or should the water come below the proper line, the float will fall, open the
valve P, and the water will instantly rush through, down the pipe O, and
immediately extinguish the fire, and thus obviate all danger.
Having thus described the nature and particulars of my said Invention,
and the manner of carrying the same into practical effect, I wish it to be
understood that I do not confine myself to the exact details herein set forth,
as such may be varied or modified without departing from the principle
thereof; but what I claim as my Invention is the system and arrangement
of levers, valves, floats, and weights in the different apparatus described by
Figs. 2, 3, and 4, which may be employed separately, or all upon one boiler,
as herein-before described.
In witness whereof, I, the said John Knowelden, have hereunto set my
hand and seal, this Fourteenth day of March, in the year of our Lord
One thousand eight hundred and fifty-seven.
Witness,
HENRY FLETCHER.
JOIN KNOWELDEN. (L.s.)