IMPROVEMENTS IN SAFETY VALVES
Year: 1880

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 VALVES." A communication from abroad by
George W. Copeland, of Boston, Massachusetts, United States of America.
PROVISIONAL SPECIFICATION left by the said William Robert Lake at
the Office of the Commissioners of Patents on the 24th December 1880.
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent
Agents, Southampton Buildings, London. "IMPROVEMENTS IN SAFETY VALVES."
[A communication from abroad by George W. Copeland, of Boston, Massachusetts,
United States of America.]
This Invention relates to improvements in safety valves in which a weighted
auxiliary piston or slide valve controls the operation of the main piston or valve,
by being actuated by the excess of pressure in the valve chamber to open a port
and close an exhaust, whereby the pressure in the valve chamber is allowed to
enter a chamber below, or at one end of the main piston and lift it, thereby
opening a direct passage from the valve chamber for the escape of the excess of
pressure, and by the diminution of pressure in the valve chamber to the required
pressure, or a pressure slightly below the required pressure, to close the port and
open the exhaust, whereby the pressure in the side chamber below, or at one end
of the piston, is allowed to escape, and the main piston is moved by the pressure in
the valve chamber to close the direct passage.
In carrying the said Invention into practice I provide the valve chamber with a
passage by which it is connected with the boiler or other pressure generator, and
with a direct escape port or passage. The main piston has two heads of unequal
area, which I term the first and second heads; the area of the second head is
somewhat less than that of the first head, and a projection is formed on the
latter.
The main piston has a
piston, the piston rod, and
hole and a chamber for the reception of the auxiliary
a weight which is carried by the latter, and is secured

page_text: thereon in any desirable manner. A passage extends from the valve chamber
through the main piston to a small annular chamber between the two heads of the
auxiliary piston. Part of the piston rod or spindle is reduced in size to provide an
annular chamber between it and the wall of the hole of the main piston below the
lower head of the piston; this part when the piston is lifted, as hereinafter
explained, permits the steam to pass through the passage in the main piston into a
chamber below the first piston head, and also connects the auxiliary piston with a
valve disc, which with a seat controls the exhaust passage extending from the last
mentioned chamber downwardly through the projection of the main piston. The
auxiliary piston and its connection are fitted very loosely in the hole and chamber
in the main piston, and they, together with the wall of the said hole and chamber,
may be nickel plated if desired. This or similar provision should be made to
reduce the amount of friction between the parts to a minimum, and also to prevent
the possibility of corrosion.
The area of the upper head of the auxiliary piston is so much greater than that
of the lower head as to allow the ordinary pressure to lift the piston and piston
rod, but the difference in area is not sufficient when the piston is loaded to allow
the ordinary pressure to lift the piston and its load until the pressure in the
chamber below the piston head exceeds the required pressure; moreover, by
proportioning the area of the two heads, so that the area of the upper head shall be
a trifle greater than that of the other head, a very light load only is necessary to
keep it seated at ordinary working pressure, while if the area be considerably
larger, a heavier load is needed. The movement of the auxiliary piston and its
load by the excess of pressure in the valve-chamber not only opens the passage to
the chamber below the first piston head but also closer the exhaust, and the
exhaust passage remains closed during the upward movement of the main piston to
open the valve for the escape of pressure as the auxiliary piston moves with it.
While the valve is blowing off and after the pressure has been reduced sufficiently
the auxiliary piston falls and closes the passage through the main piston and opens
the exhaust, and then the pressure on the lower piston head causes the main and
auxiliary pistons to move downwardly to their original position.
As the first head of the main piston is greater in area than the second head
above stated, it follows that upon the opening of the exhaust and the closing of
the passage between the valve chamber and the chamber below the first piston
head the main piston will be returned to its original position by direct pressure
from within the valve-chamber acting upon the head having the increased area
with somewhat greater power than it acts upon the other head.
A drip passage extends from the bottom of the chamber in the main piston
downwardly through the projecting portion of the main piston.
In order that the steam may pass freely into the chamber below the piston head
I groove the underside of the piston. The amount of pressure required to lift the
weight is varied by increasing or decreasing the weight, or by varying the size of
the chamber between the two heads of the auxiliary piston or the area of the
auxiliary piston itself.
In lieu of a dead weight a spring or weighted lever may be employed. Any
suitable packing may be used for packing the joints between the piston heads and
the valve casing. I may use a metallic packing consisting of a ring of sheet or
other metal shaped to fit the bore of the cylinder or valve-chamber, and having a
flange by which, with the aid of the nut, it is fastened to the piston rod.
The interior of the ring is cup shaped, and pressure upon it extends it against
the wall of the cylinder. The second piston head has wings which give it a
bearing against the valve-chamber or cylinder, when the piston-head has been lifted
to open the outlet or escape port.
As a rule the piston rises until it comes in contact with a stop or buttress on the
lower side of the diaphragm or plate of the valve casing, and the casing is enlarged
at its upper end above the piston head in order to provide for the aforesaid escape
passage,

page_text: In some cases the slide valve or auxiliary piston may be located outside the
valve-chamber and be adapted to operate the main piston, in which case the
passage which is above described as passing through the main piston would pass
from the valve chamber into a chamber corresponding to the chamber between the
two heads of the auxiliary piston and located outside the casing and containing
such auxiliary piston and devices for operating the exhaust, and upon the upward
movement of the auxiliary piston a passage would be opened into the chamber
below the piston head in the main valve.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said William Robert Lake in the Great Seal Patent Office on the
21st June 1881.
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent
Agents, Southampton Buildings, London. "IMPROVEMENTS IN SAFETY VALVES."
A communication from abroad by George W. Copeland, of Boston, Massachusetts,
United States of America.
This Invention relates to improvements in safety valves in which a weighted
auxiliary piston or slide-valve controls the operation of the main piston or valve
by being actuated by the excess of pressure in the valve-chamber to open a port and
close an exhaust passage, whereby the pressure in the valve-chamber is allowed to
enter a chamber below or at one end of the main piston and lift it, thereby opening
a direct passage from the said valve-chamber for the escape of the excess of
pressure, and by the diminution of pressure in the valve-chamber to the required
pressure, or a pressure slightly below the required pressure, to close the port and
open the exhaust passage, whereby the pressure in the side chamber below or at
one end of the piston is allowed to escape, and the main piston is moved by the
pressure in the valve-chamber to close the direct passage.
In the accompanying Drawing,―
Figure 1 is a vertical section of my improved valve, and
Figure 2 is a plan partly in horizontal section of the same.
Figure 3 is a horizontal section on the line X, X, Figure 1.
Figure 4 is a vertical section of the valve representing the position of the parts
when the valve is open or blowing.
Figure 5 is an elevation of the main piston.
Figure 6 is an elevation of an auxiliary piston and its attachments, with the
exception of the weight or load.
Like letters indicate the same parts throughout the Drawing.
A represents the valve-casing; a, the valve-chamber, and a' the passage, by
which it is connected with the boiler or other pressure generator; a² is the
direct escape port or passage from the valve chamber; as is the main piston which
has two heads a*, a³, of unequal area, the area of the head a³ being somewhat less

page_text: than that of the head a; a is a projection from the head at, and a' a portion of
the valve-casing surrounding the part aⓇ of the main piston.
The main piston a³ has a hole b and a chamber 61 for the reception of the
auxiliary piston B, the piston-rod 62, and the weight 63, which is carried by the
said piston rod, and is secured thereon in any desirable manner. A passage b
extends from the valve-chamber a, through the main piston to the small annular
chamber 65 between the two heads of the auxiliary piston B. The part 66 of the
piston rod or spindle, as I prefer to term it, is reduced in size to provide an annular
chamber b7 between it and the wall of the hole b below the lower head of the
piston; this part when the piston is lifted, as hereinafter explained, permits the
steam to pass through the passage 6 into the chamber c below the piston-head a*,
and also connects the double headed auxiliary piston B with the valve or valve
disc c², which with the seat c³ controls the exhaust passage c¹ extending from the
chamber c downwardly through the projection a6 of the main piston. The
auxiliary piston and its connections are fitted very loosely in the hole b and
chamber b¹, and they together with the wall of the said hole and chamber may be
nickel plated if desired. This or similar provision should be made to reduce the
amount of friction between the parts to a minimum, and also to prevent the
possibility of corrosion.
.
The area of the upper head of the auxiliary piston is so much greater than that
of the lower head as to allow the ordinary pressure to lift the piston and piston
rod, but the difference in area is not sufficient when the piston is loaded to allow
the ordinary pressure to lift the piston and its load until the pressure in the
chamber c exceeds the required pressure; moreover, by proportioning the area of
the two heads, so that the area of the upper head shall be a trifle greater than that
of the lower head, a very light load only is necessary to keep seated at ordinary
working pressure, while if the area be considerably larger, a heavier load is needed.
The movement of the auxiliary piston B and its load by the excess of pressure in
the valve-chamber not only opens the passage to the chamber c but also closes the
exhaust passage, which remains closed during the upward movement of the main
piston to open the valve for the escape of pressure as the auxiliary piston moves
with it. While the valve is blowing off and after the pressure has been reduced
sufficiently the auxiliary piston B falls and closes the passage b, and opens the
exhaust passage, and then the pressure on the lower piston head causes the main
and auxiliary pistons to move downwardly to their original position.
As the head a' of the main piston is greater in area than the head a³, it follows
that upon the opening of the exhaust passage and the closing of the passage between
the chambers a and c the main piston will be returned to its original position by
direct pressure from within the valve chamber acting upon the head having
the increased area with somewhat greater power than it acts upon the other
head.
A drip passage c' extends from the bottom of the chamber
through the projecting portion as of the main piston to the passage c³.
downwardly
In order that the steam may pass freely into the chamber c I groove the under
side of the piston radially from the annular chamber 67. The amount of pressure
required to lift the weight b³ is varied by increasing or decreasing the weight, or by
varying the size of the chamber 65 or the area of the auxiliary piston.
In lieu of a dead weight a spring or weighted lever may be employed. Any
suitable packing may be used for packing the joints between the piston heads and
the valve casing. I prefer however to use a metallic packing d consisting of the
ring of sheet or other metal shaped to fit the bore of the cylinder or valve
chamber, and having a flange d², by which, with the aid of the nut d³, it is fastened
to the piston head.
The interior of the ring is cup-shaped, and pressure upon it extends it against
the wall of the cylinder. The piston head a³ has wings as, which give it a
bearing against the valve-chamber or cylinder when the piston-head has been lifted
to open the escape-port.

page_text: As a rule the piston rises until it comes in contact with stop or buttress e od
the lower side of the top diaphragm or plate E of the valve-casing, and the casing is
enlarged at its upper end above the piston-head to provide for the escape passage or
passages a².
The weight 63 should exactly balance the maximum pressure desired, and any
excess of that pressure will immediately lift the auxiliary piston-weight and
spindle, thereby enabling the steam to pass into the chamber below the main
piston.
Packing of any suitable nature may be used for the heads of the auxiliary
piston B.
I have shown grooves or recesses of extending around the piston rod and
spindle for providing what is known as air packing.
It will be readily understood that the passage into the chamber c is not opened
until the piston B has lifted the spindle sufficiently to bring the upper end of the
reduced part 66 of the piston rod in line with the lower end of the passage b*.
I do not confine myself to the location of the slide-valve or auxiliary piston in
relation to the main piston as above described, as in some cases it may be located
outside the valve-chamber a, and be adapted to operate the main piston in sub-
stantially the same manner as that above described. In this case however the
passage 6* instead of passing through the main piston would pass from the valve
chamber iuto a chamber corresponding to the chamber 6 located outside the
casing A and containing the auxiliary piston and devices for operating the exhaust,
and upon the upward movement of the auxiliary piston a passage would be opened
into the chamber c.in the main-valve.
The operation of my improved safety-valve is as follows, that is to say :-
The piston rod b² is loaded by a weight which determines the amount of
pressure in the valve chamber required to lift the auxiliary piston B and the excess
of pressure in the chamber 6 over the balancing point causes the auxiliary piston
and weight to lift or rise sufficiently to connect the passage b' with the port or
annular space b7 and to close the exhaust passage, thereby allowing the pressure in
the valve-chamber a to pass into the chamber c below the piston head a', and to
force the main piston upward sufficiently to allow the escape of pressure directly
from the main chamber of the valve around the upper head a³ through the direct
passage or port a².
Upon the reduction of the pressure in the chamber 65 the auxiliary piston
automatically returns or falls, closing the passage b* and opening the exhaust
passage c', whereby the steam in the chamber c is allowed to escape, and the piston
is returned to its original position by the pressure within the main valve-chamber,
as herein before described.
•
The area of the inlet passage a¹ should be somewhat smaller than that of the
escape passage a³ in order that the pressure in the valve chamber when the valve
is blowing off may be lower than that in the boiler.
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 in a safety valve,-
First. The combination of the auxiliary double-headed piston, the auxiliary
valve-chamber 66, and the passage b₁, connecting the main valve-chamber with
the auxiliary valve-chamber, with the double-headed main piston, the valve-
chamber a, and the passage connecting the said valve-chamber between the beads
of the main piston with the boiler, all substantially as and for the purposes
specified.
Second. The combination of the valve-chamber a, a double-headed piston, one
head of which is of greater area than the other, and the passage a', connecting the
said valve-chamber between the two heads of the said piston directly with the
boiler, substantially as above set forth and for the purposes specified.
Third. The combination of the chamber a, the piston having the piston heads
a, as, the passage connecting the said chamber between the piston heads directly
with the boiler, the auxiliary weighted piston B, the passage b', the port 67, the

page_text: chamber c, the exhaust passage c', and its valve, substantially as above set forth
and for the purposes specified.
Fourth. A weighted auxiliary piston adapted, upon the excess of pressure in the
valve-chamber, to open the port connecting the valve-chamber a with a chamber
below the main piston, and to close the exhaust passage to the chamber below the
head, and upon the reduction of the pressure to close the port and open the exhaust
passage, substantially as above set forth and for the purposes specified.
Fifth. The combination of a weighted auxiliary piston for opening the port
connecting the valve-chamber with the chamber below the main piston, and for
closing the exhaust-passage, and upon the reduction of the pressure to close to
port and open the exhaust, with the chambers a and c, and the main piston a³,
all arranged in relation to each other and adapted to operate substantially as
herein described..
Sixth. A valve-chamber having the steam induction way or passage a¹ and the
steam eduction way or port a² arranged in relation to the piston, as described,
the piston having two heads of unequal area controlled as to its operation in
opening and closing the eduction way a² by the auxiliary double-headed piston
operating a slide-valve and exhaust, and by the pressure within the valve-chamber o
between the two piston heads, whereby an excess of pressure in the valve-chamber
is employed in lifting the piston, and the direct pressure in the valve-chamber, after
the reduction of pressure therein, is employed in closing the valve, substantially as
above set forth and for the purposes specified.
Seventh. The combination of a valve-chamber a having the inlet passage a' and
the outlet passage a³, with a double-headed piston arranged in relation to the inlet
passage, as described, and provided with the passage 6, the chamber c below the
lower head of the piston, and an auxiliary piston controlling a slide-valve in a
passage between the two chambers a and c, substantially as above set forth and for
the purposes specified.
In witness whereof, I, the said William Robert Lake, have hereunto set my
hand and seal, this Eighteenth day of June, in the year of our Lord One
thousand eight hundred and eighty one.
W. ROBT. LAKE. (L.S.)