IMPROVEMENTS IN SAFETY VALVES FOR STEAM BOILERS
Year: 1875

page_text: LETTERS PATENT to William Robert Lake, of the Firm of Haseltine,
"
Lake, & Co, Patent Agents, Southampton Buildings, London, for
the Invention of “ IMPROVEMENTS IN SAFETY VALVES FOR STEAM BOILERS,'
-A communication from abroad by Alexander Wilson, of Emerald
Hill, Victoria, Australia, Engineer, Surveyor to the Victoria Steam
Navigation Board.
COMPLETE SPECIFICATION filed by the said William Robert Lake at
the Office of the Commissioners of Patents, with his Petition and
Declaration, on the 17th June 1875, pursuant to the 9th Section
of the Patent Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM.
ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London, send greeting.
WHEREAS I am in possession of an Invention for "IMPROVEMENTS IN
SAFETY VALVES FOR STEAM BOILERS," and have petitioned Her Majesty to

page_text: grant unto me, my executors, administrators, and assigns, Her Royal
Letters Patent for the same, and have made solemn Declaration that
it has been communicated to me from abroad by Alexander Wilson,
of Emerald Hill, Victoria, Australia, Engineer, Surveyor to the Victoria
Steam Navigation Board.
'
5
NOW KNOW YE, that I, the said William Robert Lake, do hereby
declare that the following Complete Specification, under my hand and
seal, fully describes and ascertains the nature of the said Invention,
and in what manner the same is to be performed, in and by the following
statement, reference being had to the accompanying Drawing forming 1
a part of this Specification:-
Safety valves as at present constructed do not open quickly enough to
allow of a sufficient escape of steam until the pressure has risen to a
considerably higher point (say several pounds more) than that to which
they are nominally set, neither will they close until the pressure has 1
fallen to the same extent below what the valve would seem to indicate.
This is because they do not act promptly enough. These objections I
have remedied by my present Invention.
Further the great weights which are commonly used for loading
safety valves, especially in marine engines, are a great objection, whilst 2
the amount of steam lost by reason of the "listing" and pitching of the
vessel at sea, is considerable. Now by my Invention these weights are
almost entirely dispensed with, and the loss of steam occasioned by the
"listing" and pitching is altogether obviated.
My safety valves may be described as double valves, inasmuch as 2
there is in each a small upper valve loaded with a direct weight to the
required pressure, and a large lower valve loaded with the pressure of
the steam in the boiler. This latter feature of a steam loaded valve is
the essential peculiarity of my Invention, and may be applied with
great variations of details, although in the accompanying Drawing I³
have illustrated what I believe to be the best method of its application.
Figure 1 is a longitudinal section of apparatus embodying this Inven-
tion; Figure 2 is an end elevation of the same.
Like letters indicate the same parts throughout the Drawing.

page_text: A' is a vertical spindle on which is a small upper valve B, covering
steam ports B' consisting of flutings in spindle. A and leading from
steam space C to upper chamber D. Just below these fluted ports or
passages is a metal piston E having a small steam passage E' through it
to admit of the passage of steam from its lower to its upper side. The
vertical spindle A terminates at A', fitting in the stem E of the
piston E, which proceeding downwards terminates in a valve F covering
a steam port leading to a silent blow off or to funnel. A slot E³ is made
in said stem to allow the steam pressure to act against the bottom of
spindle A; G is a steam pipe proceeding from the boiler; H, H, are the
weights or springs which regulate the steam pressure in the boiler; I is
a pipe for easing the pressure by simply turning a cock (not shown) and
so releasing a portion of the steam from chamber C, thus enabling the
large lower valve to lift. .
The operation of this Invention is as follows:-Suppose the safety
valve is to be set at a pressure of thirty pounds to the square inch, and
that the total sectional area of the flutings B' is half an inch, I load the
small upper valve B which covers them with fifteen pounds weight.
Communication can then be opened with the boiler by means of the
steam pipe G, and whenever the pressure rises above that to which it is
set, the small upper valve B lifts and allows the steam to escape from
the chamber C through ports B¹ into the waste steam pipe, thus necessi-
tating the lifting of the lower valve F. This latter will rise one-fourth
of its diameter so as to admit of a free outflow of steam before the
pressure has risen to any perceptible extent above that to which the
boiler is set, closing again immediately the pressure falls to the set
standard.
Having thus fully described the said Invention as communicated to me
by my foreign correspondent, and the manner of performing the same, I
wish it understood that I do not confine myself to the precise details

page_text: parts of my apparatus forming a complete safety valve, substantially as
herein described and illustrated in the Drawing.
In witness whereof, I, the said William Robert Lake, have here-
unto set my hand and seal, this Seventeenth day of June,
in the year of our Lord One thousand eight hundred and
seventy-five.