IMPROVEMENTS IN PRESSURE REDUCING VALVES to be as follows
Year: 1885

page_text: I, JOHN REED FOTHERGILL, of N° 1 Bathgate Terrace, West Hartlepool, in the
County of Durham, Superintending Marine Engineer, do hereby declare the nature
of said invention for "IMPROVEMENTS IN PRESSURE REDUCING VALVES to be as
follows:-
"
My invention has reference to a pressure reducing valve of the kind in which
there are two pistons connected together, the areas of these two pistons being to
one another as the difference of pressure required and the arrangement such that
when the pressure against the smaller piston exceeds the opposing pressure against
the larger piston a passage or passages is or are opened whereby fluid under
pressure can flow from behind the smaller piston and expand into a chamber in
front of the larger piston to be available for use at a correspondingly reduced
pressure.
In such a reducing valve according to my invention provision is made for escape
or withdrawal from the space or chamber situate between the two pistons of fluid,
or water resulting from condensation of steam, that may escape past the pistons,
which arrangement renders it practicable to use pistons not packed very tightly,
and which therefore are free to work easily in their respective chambers. The
body or shell of the apparatus is bored to two suitable diameters having a common
axis the one to receive and guide the smaller piston and the other the larger piston.
Between these two cylindrical parts a stop is provided to limit the stroke of the
pistons. An annular passage with a series of ports (or a series of passages) connects
the smaller cylinder with the larger and when the ports in the smaller cylinder are
uncovered, fluid (which I will assume to be steam) under pressure flows from
behind the smaller piston into the chamber at the further end of the larger cylinder
as already stated. The escape of any steam that may leak past the pistons or of
water that might otherwise accumulate between the pistons, thus obstructing their
free action, takes place by means of pipes or passages which for this purpose are
arranged to establish communication between the interior of the body or shell
of the apparatus between the pistons and the outer chamber or any suitable
receptacle.
From the above description it will be understood that when steam from the
boiler presses on the smaller piston that piston is forced towards and against the
stop thus opening the ports of the smaller cylinder and allowing steam to flow by

page_text: the annular passage (or series of passages) to the further side of the larger piston;
this will continue until such an accumulation of pressure occurs as to overcome the
pressure on the smaller piston, whereupon the larger piston will be forced back
against the stop, moving with it the small piston whereby the ports will be closed
until the pressure against the larger piston falls sufficiently to permit of the return
movement of it and the small piston being effected by the pressure against the
latter. Thus the pistons are in a state of constant motion and the arrangement is
such that if they be carefully fitted up they will run for a considerable time without
material wear.
The periphery of the smaller piston is provided with packing at or near its
respective ends, or it may be grooved or formed as two packed pistons so that the
back pressure of fluid or steam through the ports closed by it shall not compress
the packing and escape past the piston,
Improvements in Pressure Reducing Valves.
I, JOHN REED FOTHERGILL, of N° 1 Bathgate Terrace, West Hartlepool, in the
County of Durbam, Superintending Marine Engineer, do hereby declare the nature
of this invention and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement:-
My invention has reference to a pressure reducing valve of the kind in which
there are two pistons connected together, the areas of these two pistons being to
one another as the difference of pressure required and the arrangement such that
when the pressure against the smaller piston exceeds the opposing pressure against
the larger piston a passage or passages is or are opened whereby fluid under
pressure can flow from behind the smaller piston and expand into a chamber in
front of the larger piston to be available for use at a correspondingly reduced
pressure.
In such a reducing valve according to my invention provision is made for escape
or withdrawal from the space or chamber situate between the two pistons of fluid
or water resulting from condensation of steam, that may escape past the pistons,
which arrangement renders it practicable to use pistons not packed very tightly,
and which therefore are free to work easily in their respective chambers. The
body of the apparatus is bored to two suitable diameters having a common axis
the one to receive and guide the smaller piston and the other the larger piston.
Between these two cylindrical parts a stop is provided to limit the stroke of the
pistons. An annular passage with a series of ports (or a series of passages) connects

page_text: the smaller cylinder with the larger and when the ports in the smaller cylinder are
uncovered, fluid (which I will assume to be steam) under pressure flows from
behind the smaller piston into the chamber at the further end of the larger cylinder
as already stated. The escape of any steam that may leak past. the pistons or of
water that might otherwise accumulate between the pistons thus obstructing their
free action takes place by means of pipes or passages which for this purpose aro
arranged to establish communication between the interior of the body or shell
of the apparatus between the pistons and the outer chamber or any suitable
receptacle.
Referring to the accompanying drawings Fig. 1 shews in vertical section an
automatic reducing valve constructed according to this invention; Fig. 2 represents
the same in horizontal cross section taken in line A, B. of Fig. 1; Fig. 3 is a
horizontal cross section taken in the line C. D of Fig. 1, and Fig. 4 is a horizontal
cross section in E. F Fig. 1. Figs. 6 and 7 show the arrangement of steam ports
at A. B and C. D respectively.
a is the shell of the apparatus containing an inner part or body b which is borėd
to two suitable diameters c and d having a common axis, the one to receive and
guide the smaller piston e and the other the larger piston f. g is a stop between
these two cylindrical parts to limit the stroke of the pistons. h represents an
annular passage (or it may be a series of passages) with a series of ports i, k, l, m
connecting the smaller cylinder with the larger. The pistons are packed as shown
or in any other suitable manner, In the example illustrated the larger piston is
made double, that is to say, a passage n is provided in it for the purpose of
establishing a communication between the passage h and the chamber d. Tie pieces
or feathers o are provided in the larger piston. p is a screwed spindle suitably,
packed and guided and provided with a hand wheel 2. r. are small relief holes
or ports in communication with the annular passage or outer chamber h. 8. 8 are
relief passages from the space between the two pistons to the external atmosphere
or any suitable receptacle. The screwed nozzles y. y of the relief pipes 8. s are for
connecting drain pipes to carry off any escaping steam or condensed water or other
fluid to a suitable receptacle.
The ports i. k. . m are arranged about the circumference of the small and large
cylinders in rows as shown in Figs. 6 and 7. t is a bracket by means of which the
apparatus may be fixed in a suitable manner.
:
High pressure steam is admitted by means of the passage wo to the high pressure
pistone and uncovers the ports i. k. by forcing the piston against the stop g. The
steam then flows through the ports (or series of ports) i. k, through the annular
passage (or passages) or outer chamber h, through the ports (or series of ports) l. m,
through the larger piston f, and into the chamber d at the further end of the larger
piston and it will continue to do so until such an accumulation of pressure occurs
as to overcome the pressure upon the smaller piston whereupon the larger piston
will be forced back against the stop g thereby closing the ports i. 1. l. m, and
establishing a communication from the outer chamber or annular passage (or series
of passages) h to the atmosphere or any suitable receptacle by way of the relief
pipes ports or passages r. r and s. s, until the pressure against the larger piston falls
sufficiently to permit of the return movement of it and the small piston being
effected by the pressure against the latter. Thus the pistons are practically in a
state of constant motion. Accumulation of pressure or of water is prevented by
means of the relief passages s 8 through which any steam that may leak past the
pistons and any water that may accumulate between the pistons can escape, such
steam as may leak past the piston e through the ports i, k, or past the piston f
and through the ports l, m, into the annular passage or outer chamber h passing to
the relief passages 88 through the holes or ports r. r and the space between the
pistons.
By screwing in the spindle p, the valve may be forced in against the stop so
as to be full open, when steam at full or reduced pressure is required to be passed
through the apparatus in either direction.

page_text: Figs. 8 and 9 shew an arrangement in which the same object is effected by
means of a cam u attached to a spindle v which may be rotated at will so as to
depress or release the valve.
By setting the feathers or tie pieces o in the large piston at an angle the valve
is caused to partially rotate when in motion, thereby preventing irregular wear of
the cylinder faces.
In an automatic reducing valve constructed according to this invention the
liability of leakage is even under high pressure steam reduced to a minimum and
the pressure on the reduction side of the valve will not increase even if there exist
leakage past the pistons. Moreover it will be noted that the arrangement is such
as to obviate the use of springe, weights stuffing boxes and glands in direct
connexion with the movement of the valve..
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I hereby declare that
I do not lay any general claim to the use in a reducing valve of two unequal
cylinders and pistons, but what I do claim is :-
"
1. In a pressure reducing valve having differential pistons that work in cylinders
connected by a passage chamber or passages such as h, providing substantially in
the manner described above with reference to the drawings annexed, for escape of
fluid that may leak past the pistons, thereby preventing accumulation of pressure
or water as set forth.
2. The improved pressure reducing valve constructed arranged and operating
substantially as described with reference to and shown in Figs. 1 to 7 of the
drawings annexed.
[