IMPROVEMENTS IN SAFETY-VALVE APPARATUS
Year: 1881

page_text: LETTERS PATENT to William Robert Lake, of the Firm of Haseltine, Lake,
& Co., Patent Agents, Southampton Buildings, London, for an Invention
of "IMPROVEMENTS IN SAFETY-VALVE APPARATUS." A communication from
abroad by Adolf M. Pleischl, of Vienna, Austria.
PROVISIONAL SPECIFICATION left by the said William Robert Lake at
the Office of the Commissioners of Patents on the 16th May 1881.
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent
Agents, Southampton Buildings, London. "IMPROVEMENTS IN SAFETY-VALVE
APPARATUS." [A communication from abroad by Adolf M. Pleischl, of Vienna,
Austria.]
This Invention relates to safety-valves for steam-boilers, and provides means
whereby such valves may be lifted or opened to a greater extent when the steam
"blows off," than is the case with the valves heretofore used, and thus the danger
of explosion is diminished or obviated.
The safety valves of ordinary construction rise or open only to a very small extent,
and therefore the steam cannot escape sufficiently fast through the too narrow
sectional area thus provided, and may consequently (notwithstanding the safety-
valve), assume such a degree of tension as to cause danger of an explosion.
By the escape of steam from a safety valve, the air is carried away with the
steam, both above and below it, and then the air from above presses down
with great power, and thus prevents the rising of the valve as far as it should
rise.
This pressure of the air from above upon the valve is prevented by the con-
struction hereinafter described, and practical experiments have demonstrated that a
safety-valve provided with an apparatus constructed according to this Invention
has risen or opened twice as far as is the case with a valve unprovided with such
apparatus.
In carrying the said Invention into practice, I provide the valve proper with a
cowl, hood, chamber, or shell which surrounds the valve, and which is open at the

page_text: top, and through the aperture thus provided the steam escapes, and thus prevents
the pressure of air downward upon the valve.
Or instead of the cowl, a plate, disc, or other covering may be placed over the
valve, and may be straight, bent, or conical; it may be made of sheet metal or cast-
metal, and in one piece or in several pieces, and in this case the steam escapes side-
wise, but the downward pressure of air upon the valve is prevented. This plate,
disc, or other covering may be placed over the valve lever, but it is preferable to
place it between the lever and the valve.
In some cases a ring is provided which serves for supporting the disc or cover.
The following may be used as a modification of the constructions above described,
that is to say :-
Upon the valve I place a hollow cylinder, through which passes the connecting
piece whereby the valve is depressed. The higher the said hollow cylinder is made,
the more easily the valve opens

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Williain Robert Lake in the Great Seal Patent Office on the
10th November 1881.
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent
Agents, Southampton Buildings, London. "IMPROVEMENTS IN SAFETY-VALVE
APPARATUS." A communication from abroad by Adolf M. Pleischl, of Vienna,
Austria.
This Invention relates to safety-valves for steam-boilers, and provides means
whereby such valves may be lifted or opened to a greater extent when the steam
"blows off" or escapes, than is the case with safety-valves as hitherto constructed;
and thus the danger of explosion is greatly diminished.
Safety valves of ordinary construction rise or open to a very small extent only,
and therefore the steam cannot escape sufficiently fast through the too narrow
sectional area thus provided, and may consequently, notwithstanding the opening
of the safety-valve, assume such a degree of tension as to cause danger of an
explosion.
By the escape of steam from a safety-valve, the air is carried away with the
steam both above and below the said valve, and the air then exerts great pressure
upon the upper surface of the valve, and thus prevents the rising of the same to its
full extent.
This pressure of the air upon the upper surface of the valve is prevented by the
construction hereinafter described, and practical experiments have demonstrated
that a safety-valve provided with apparatus constructed according to this Invention
is capable of rising or opening twice as far as is the case with a valve which is not
provided with such apparatus.
This apparatus consists of a hood, shell, or cover so arranged in relation to the
valve that during the escape of steam no flow or pressure of the air against the
upper surface of the valve can take place.
In Figures 1 and 2 of the Drawing, which are vertical sections, I have shewn the
valve x surrounded by a cowl, hood, or shell y, which is open or has an aperture at
its top; through this aperture the steam escapes on the rising of the valve, and thus
prevents the access of air into the said hood or shell, and the consequent downward
pressure of the same upon the upper surface of the valve.
Or instead of the cowl or hood y, a plate, disc, or other cover may be placed over
or above the valve x, and may be straight, bent, or conical. This cover may be
made of sheet metal or cast, and in one piece, or in several pieces and is so arranged
in relation to the valve that the steam escapes sidewise instead of in an upward
direction, as in Figures 1 and 2.
Figures 3, 4, 5, and 6, represent in section various constructions of the said covers
and methods of applying the same. In some cases apertures may be formed in the
cover, as shewn in dotted lines in Figures 5 and 6. The plate, disc, or cover y may
be placed above the valve-lever, but it is preferable to place the said cover between
the said lever and the valve.
Figure 1 is a side elevation of the hood or shell illustrated in Figure 1, and
shews means for permitting the same to be readily fixed in the proper position.
Figure 2 is a plan or top view of a portion of the hood or shell, represented in
Figure 2, and shews the same provided with means to enable it to be readily
secured in position.
Figure 3*, 4, and 5*, are side elevations of the hoods or covers shewn in Figures
3, 4, and 5.

page_text: Figure 6 is a plan or top view of a ring y', which may be employed for supporting
the disc y, as shewn in Figure 6.
Instead of arranging my improved apparatus as above described, I in some cases
modify the same as follows, that is to say!:-I attach to, or form upon the valve x a
hollow cylinder y2, as shewn in Figure 7, through which passes the connecting piece
or rod whereby the valve is depressed. The higher the said hollow cylinder y² is
made the more easily will the valve open.
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 claim,―
A safety-valve provided with a fixed hood or cover, arranged substantially as set
forth, so that during the escape of steam from the said valve there will be no flow
or pressure of air upon the upper surface of the same.
In witness whereof, I, the said William Robert Lake, have hereunto set my
hand and seal, this Tenth day of November, in the year of our Lord One
thousand eight hundred and eighty one.