Improvements in Combined Relief and Back Pressure Steam Valves.
Year: 1899

page_text: Date of Application, 13th June, 1899 -Accepted, 29th July, 1899
COMPLETE SPECIFICATION.
Improvements in Combined Relief and Back Pressure Steam Valves.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency for Foreign
Patent Solicitors, G, Lord Street, Liverpool, and 6, Bank Street, Manchester, both
in the County of Lancaster, 118, New Street, Birmingham, in the County of
Warwick, and 322, High Holborn, in the County of Middlesex, Civil Engineer,
do hereby declare the nature of this invention (which has been communicated to
me by The Foster Engineering Company, of 21 and 23, Prospect Street, Newark,
New Jersey, United States of America), and in what manner the same is to bo
performed, to be particularly described and ascertained in and by the following
statement:—
This invention relates to a combined relief and back pressure valve of the
class adapted to be used in connection with large steam engines of various types
in which the steam, after having been utilized in the engine and having given
up its energy, passes into what is commonly known as a condenser wherein the
steam is converted into water. The condition usually prevailent in these con-
densers is a vacuum, or partial vacuum, produced by reason of the exhaust steam
being cooled and converted into water, thereby greatly reducing its volume, and
also by the aid of air or vacuum pumps which exhaust any remaining pressure left
after the condensation. If from failure of the cooling appliances, or failure on
the part of the vacuum pumps, the condition in the condensers should be changed
from a state of vacuum to one of pressure, this pressure would ordinarily
accumulate so rapidly that the engine would only make a few strokes or revolu-
tions before the exhaust would equal, or nearly so, the initial pressure as to
cause the engine to come to a stop. To prevent such conditions this valve is
intended to be connected to the condenser in such a manner that as long as the
pressure in the condenser is below that of the atmosphere the valve will remain
closed, thereby excluding the atmosphere, but as soon as there is a failure of the
cooling appliances, or of the vacuum pump, and the pressure in the condenser
becomes equal to or greater than atmospheric pressure; then the function of this
valve is to instantly open and let any excess pressure pass off freely to the
atmosphere. If, as is sometimes the case, it is desired that the engine shall
exhaust into the condenser or receptacle at some determined pressure above
atmospheric, then this valve may be converted into what is commonly known
as a back pressure valve," by means of suitable weights attached to levers in
connection with the valve. These weights having been positioned for some
determined pressure, whenever the exhaust exceeds that pressure, then the valve
will freely open and pass off all such excess, closing again as soon as the pressure
reaches its normal or predetermined point. Valves as usually required for these
particular services are of such large dimensions as to require their construction
in the baser metals, usually iron, in order that their cost may not be excessive.
The movable or operative parts being very large and heavy and the base material
being very susceptible to corrosion and rapid deterioration, under the prevailing
conditions of moisture and very low or entire absence of heat, the operative parts
"

page_text: after remaining in one position for a considerable time are usually so corroded
as to be almost inoperative and will not open freely and quickly as might be
required in an immergency. Again, the valve proper, with its seat, together
with its corresponding seat in the valve body or casing, if made of iron, as is
usually the case, soon deteriorates and becomes so cut or eaten away as to leak
badly and thus destroy the efficiency of the valve.
To avoid or overcome these various difficulties my invention consists in a com-
bined relief and back pressure valve comprising the features of construction and
novel combinations of parts hereinafter set forth.
In the annexed drawings Fig. 1 is a vertical central section of my improved
valve, Fig. 2 is an elevation of the same from the outlet end, a portion of the
casing being broken away to more clearly illustrate a part of the interior
mechanism.
for its
In Fig. 1 the reference 1 is an inlet casing having an annular flange
connection to the condenser or steam receptacle, 3 is the valve casing or body
having an inner annular flange 4 for its attachment to the casing 1; some suitable
is also pro-
packing material being preferably interposed. This valve casing
vided with an annular flange 5 surrounding the inlet 5", to which latter may be
bolted a suitable pipe to conduct the exhaust steam where desired. At the inlet
to the casing 3 is arranged a circular dish-shaped valve 6 having a central hub 7
and radial strengthening webs 8 on one side. To the other side of this dish-
shaped valve G is attached by means of the flange 10 and bolts 1 a spindle or
arbor 9, the same being made of some non-corrosive or comparatively non-
corrosive metal such as bronze or steam metal. The spindle 9 passes through a
sleeve 12 and is held therein by a nut 13 at one end. The sleeve 12 is also sup-
ported in a central axial position in relation to the inlet casing 1 and valve
casing 3 by means of a curved lever 14, connected at its upper end to said sleeve
by means of the bronze pin 15, and connected at its lower extremity by a similar
pin 16 to a bridge or girder piece 17, which is in turn attached to the casing 3
by studs or bolts IS, as shown in Fig. 2. To the other or rear end of the sleeve 12
is connected a straight arm 19, which is jointed at its upper end to said sleeve and
at its lower end to the valve casing 3. These levers or arms 14 and 19 connect
through the sleeve 12, and are the means whereby the spindle 9 and valve 6 are
held at all times in a position axial to or parallel with the axial line of inlet
casing 1 and the valve casing 3.
In the lower side of the elbow or curved portion of the lever 14 is a recess 20,
into which is fitted a link 21 through which the lever 14 is connected to the
enlarged bifurcated upper end of a spindle 22 by suitable pins 23 and 24 as
shown.
The spindle 22 is fitted nicely to and passes freely through the central opening
in a gland 25 which has an enlarged flange at its upper end; between which
flange and the casing or body 3 is interposed a thick washer or disc 26 of some
springy yielding material such as rubber. A nut 27 is threaded over the lower
end of the flange 25 in such manner as to slightly compress the washer 26 to
form a fluid tight joint around the gland 25. This washer 26 also forms a buffer
to receive the blow and reduce the shock consequent upon the upper enlarged
portion of the spindle 22 coming in contact with and stopping upon the gland 25
whenever the valve 6 is suddenly thrown open to relieve any excessive pressure.
To the lower or outer end of the spindle 22 is attached a yoke piece 28, through
which passes a lever 29 connecting with said yoke and pivotted to a bracket 30,
fastened to the casing 1 at one side of the yoke. This lever 29 is for the purpose
of connecting suitable weights (not shown) to counterbalance the weight of
valve 6, spindle 9, sleeve 12, and levers 14 and 19, or to weight these parts
against a desired back pressure; also, by means of this lever 29 the valve may be
operated manually when so desired.
To overcome the evil results consequent to corrosion and eating away of iron
valve seats, as generally provided in large valves of this class, I have provided

page_text: the inlet casing 1, also the valve 6, with annular seat rings 31 and 32, respectively,
of copper or other suitable non-corrosive metal. The grooves to receive and
hold these seat rings in place are made dovetailed or wider at the bottom part.
The seat rings are placed in said grooves and rolled or crushed until they expand
and fill the grooves tightly, when they are machined or faced true so that the
two seats may come in perfect opposing contact at all points around the circle.
To further facilitate the perfect contact, the seat ring 32 on valve 6 is made com-
paratively narrow and slightly convex on its face in order that it may crush or
embed inself into the opposing seat ring in casing 1. This condition of contact
between the seats will more especially occur whenever there is a state of vacuum
at the inlet side of the valve, or when the lever 29 is weighed to hold the valve 6
with some force against the seat in casing 1.
It will be seen from the construction and arrangement of the lever 14 and
arm 19, that when the valve 6 is closed or resting against the seat in casing 1,
it will remain of its own weight in this closed position until some force such as
steam pressure from the inlet side of the easing 1, or manual force applied to
lever 29, is exerted to throw the valve open; then it will remain open until the
manual force is again applied to close it, or in case the lever 29 is weighted to
hold the valve closed against a required steam pressure in the inlet casing 1;
then when the pressure becomes excessive, so as to open valve 6,
will remain.
open only so long as the pressure remains excessive or above normal, the weight
on lever 29 returning the valve to its seat immediately upon the reduction of
pressure.
In the use of relief valves of this class, it may sometimes happen that the
vacuum is momentarily lost and restored in comparatively quick succession. In
this case the valve may chatter or hammer on its seats with a succession of rapid
blows, due to the repeated partial opening and closing between the strokes of the
engine. Such hammering would not only be annoying but might become so
violent as to injure the seats or break the movable parts of the valve. To avoid
this difficulty I have provided the well known dash-pot 33 which should be used in
connection with the lower end of the spindle 22; this dash pot being filled with
oil or some non-corrosive material in such manner that the spindle 22 would be
permitted to move slowly up or down and not rapidly, thus effectually preventing
violent and rapid movement of the valve mechanism.
When from continued service, the seats 31 and 32 become worn, or eaten away,
they may be reground by attaching a handle or wrench bar to the threaded
end of the spindle 9, where it projects through nut 13, and revolving the valve 6
on its bearings in the sleeve 12; some abrasive material such as fine emery having
been smeared on and between the faces of the seat rings.
It will be obvious that a combined relief and back pressure valve of the
character described can be applied to advantage in various situations, for control
of conditions similar to those hereinbefore mentioned.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is;-
-
First. In valves of the kind described, the combination with a casing having an
inlet and an outlet, and a valve provided with a spindle and arranged to control
said inlet, of a lever and an arm connected with the valve spindle and jointedly
supported in the valve casing to permit the valve and its spindle to move parallel
with the axis of the casing inlet and ensure them being at all times maintained in
an axial position parallel with the axis of the inlet and valve casing, substantially
as described.
Second. In valves of the kind described, the combination with a valve casing
and a valve provided with a spindle, of a sleeve secured on the valve spindle, and
lever mechanism mounted in the valve casing and connected with said sleeve for
the purposes substantially as described.

page_text: Third. The combination with a valve casing and a valve provided with a
spindle, of a curved lever mounted in said casing and connected with the valve
spindle at a point adjacent to the valve, an arm mounted in the valve casing and
connected with the valve spindle near its end, said lever and arm being arranged
to permit the valve and its spindle to move parallel with the axis of the casing
inlet, whereby the valve and its spindle are maintained at all times in an axial
position with relation to the valve casing inlet, a spindle extended through the
valve casing and having a link connection with the elbow portion of the curved lever
in said casing, a fluid-tight gland around said spindle, and a lever connected with
the outer end of said spindle and to which a weight may be attached to counter-
balance the valve and its connections, or to weight the same against a desired back
pressure, substantially as described.
Fourth. The combination with a valve casing having an inlet and an outlet
and a valve provided with a spindle and arranged to control said inlet, of a sleeve
secured on the valve spindle, a curved lever mounted in said casing and connected
with the valve spindle through said sleeve at a point thereon adjacent to the valve,
an arm mounted in the valve casing and connected with the valve spindle through
said sleeve at a point near the end of the spindle, said lever and arm being
arranged to permit movement of the valve and its spindle parallel with the axis
of the casing inlet, and means for applying a weight or weights to said lever
mechanism to counterbalance the valve or to adjust it against a desired back
pressure, substantially as described.
Fifth. The combination with a valve casing, and a valve provided with a spindle,
of lever mechanism connected with the valve spindle and arranged to permit
movement of the valve and its spindle parallel with the axis of the casing inlet,
a spindle extended through the valve casing and having a link connection with
said lever mechanism, and a dash pot connected with said spindle, substantially as
described.
W. P. THOMPSON & Co.,
11, Burlington Chambers, New Street, Birmingham,
Also of Liverpool, London and Manchester,
Patent Agents for the Applicant.