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1. * GB780198 (A)
Description: GB780198 (A) ? 1957-07-31
Improvements in or relating to valves for controlling fluid pressure and
systems incorporating such valves
Description of GB780198 (A)
PAT'ENT SPECIFICATION
Inventor: LAURENCE SIDNEY BECKER 78O0 198 Date of Application and
filing Complete Specification June 25, 1954.
No. 18786154.
Complete Specification Published July 31, 1957.
Index at acceptance:-Classes 75(1), TG(17: 22); and 135, VEIF, VL(2D:
3D: 4D: 6D: 8D).
International Classification:-FO6k. F23d.
COMPLETE SPECIFICATION
Improvements in or relating to Valves for Controlling Fluid Pressure
and Systems Incorporating such Valves' We, " SHELL" RESEARCH LIMITED,
a British Company, of St. Helen's Court, Great St. Helen's, London,
E.C.3, do hereby declare the invention, for which we pray that a
patent may be granted to us, and the method by which it is to be
performed, to be particularly described in and by the following
statement: This invention relates to valves for controlling fluid
pressure and to systems incorporating such valves and is particularly
but not exclusively applicable to multiple burner installations
supplied with liquid fuel.
Although the present invention is applicable to any type of valve
controlling fluid pressure or to any system incorporating such a
valve, e.g. a servo system employing fluid under pressure, for the
sake of simplicity, reference is made herein primarily to valves
controlling the pressure of liquid fuels and the burner systems
incorporating such valves.
In a multiple burner system employing liquid fuel, the burners, often
arranged on a ring main, are supplied with liquid fuel through
suitable conduits in which liquid fuel pressure is maintained by a
pump which is generally of constant speed type. If all burners are

2. adjusted, to give satisfactory combustion when all burners are
operating, operation on less than the whole number of burners
introduces difficulties as the pressure of the system increases when a
number of burners are shut down. This means that the burners remaining
in operation receive fuel at a pressure which is higher than that for
which they are adjusted and so give inefficient and smoky combustion.
Simple pressure regulating valves of known type, comprising a conical
valve seating, a conical valve and a compressed spring acting on the
valve are incapable of maintaining reasonably constant pressure in
such systems.
Diaphragm-type valves are capable of providing better pressure
regulation than these simple valves. Valve diaphragms, however, LPrice
3s. 6d.] are liable to deteriorate under the effect of the pressure
(and possibly high temperature) of the fluid being controlled, and it
has been found that diaphragm-type valves need frequent maintenance to
keep the diaphragm flexible and leak-proof.
Other systems involving pressure sensitive elements and relays are too
complicated and expensive for the majority of multiple burner liquid
fuel installations. 55 One object of the present invention is to
provide a pressure-controlling valve of relatively simple construction
and operation which will provide improved pressure regulation without
being as expensive to produce as 60 the more complicated systems just
referred to.
According to the present invention a pressure controlling valve
comprises a ported hollow sleeve fixed within a valve housing, fluid
flow passages leading from the exterior 65 of the housing to the
exterior of the ports in the sleeve, a valve member within the sleeve
in the form of a piston which member is mounted in bearings within the
sleeve so that it moves axially with substantially only rolling
friction at least between a position in which one or more passages
through or around it provide a fluid flow channel between two or more
of the ports of the sleeve and a position in which fluid flow between
said ports is 75 blocked, a spring or weight biassing arrangement for
exerting an axial force on the valve member in one direction, and
fluid compartments at both ends of the valve member such that the
pressure of any fluid within them 80 exerts an axial force on the
valve member, whereby the position of the valve member in operation
will depend on the force exerted by the biassing arrangement and the
fluid pressures in the said compartments. 85 Preferably the sleeve is
of hardened steel, the valve member being a piston which is spaced
therefrom by a small clearance and carries at or near each end a set
of steel balls which contact the steel sleeve. The biassing 90 780,198
arrangement is preferably a spring one, in which the spring is under
tension. A spring under compression may be used for this purpose,

3. however, providing that the spring dimensions are such that when
loaded it does not buckle and touch any neighbouring structure such as
the walls of its container. The use of a tension spring avoids this
possibility altogether.
Where the control pressure is low and is not required to be adjustable
it is practicable to use a dead-weight in place of the spring. In this
case, provided the valve is assembled in a vertical position, the
pressure balancing force is on the piston is fixed and invariable.
In pressure-controlling valves according to the present invention in
which means are provided for varying spring tension, a further feature
of the present invention is the provision of means whereby no torsion
forces are imparted to the spring.
The pressure controlling valve of the present invention may be
employed as a surplus (or back pressure) valve, or a pressure reducing
valve; in both cases it is possible to control the pressure between
two points which may be remote from the inlet and outlet connections
to the valve.
The invention is further illustrated by the accompanying drawings in
which:Figure I shows a part section along the longitudinal axis of a
surplus type valve according to the present invention; Figure II shows
an exploded view partly in section of the liquid flow controlling
piston of the valve in Figure I; Figure III shows a part-section along
the longitudinal axis of a portion of a pressure reducing valve (the
remaining part of the valve structure being as shown in Figure I);
Figure IV shows diagrammatically a valve as shown in Figures I and II
in series with the ring main of a multiple burner liquid fuel system,
and Figure V shows diagrammatically a valve as shown in Figure III
incorporated in a multiple burner liquid fuel system.
Referring to Figures I and II, the valve comprises a
liquid-flow-controlling piston 1, co-operating with a sleeve 7
supported in a valve body or housing 30 having an inlet connection 11,
an outlet connection 12, an end cap 16 and an extension sleeve 25
housing a helical spring 17 and means for adjusting the tension on
this spring.
The piston 1 is made of hardened and ground steel and has an annular
groove 6 (see Figure II) and each end reduced in diameter to
accommodate a brass cage 2 in the slots of which eight steel balls 3
can freely move. The assembly is held together by threaded mild steel
end plugs 4 and 5. The end plugs are fitted after the insertion of the
piston in the sleeve 7, also of hardened and ground steel, and serve
to limit the longitudinal movement of the piston and prevent loss of
the steel balls 3. The purpose of the steel balls 3 is to allow the
piston 1 to move longitudinally within the sleeve 7 with only rolling
friction, there being a small clearance (a half-thousandth 71 inch or

4. less) between the piston 1 and the sleeve 7. The sleeve 7 has two
diametrically opposite ports 8 and 10, and it fits tightly inside the
mild steel housing 30 provided with the inlet connection 11 and an
outlet connec- 7! tion 12 and channels 13 and 9 associated with these
connections.
A spindle 14 passes through the piston 1 and is secured by nut 15. The
opposite end of this spindle is attached to the helical exten- 8 sion
spring 17. A force extending the spring 17 may be applied by rotation
of the threaded spindle 22. This spindle is connected to spring 17
through a ball race outer housing 20, balls 19 and inner housing 18
which is secured S5 to the spring 17. In this way, the spring may be
extended without participating in the rotary motion of screw 22. (The
piston assembly is not capable of and is not intended to have
anti-frictional rotary motion within 90 the sleeve 7). Flexible-walled
sealing rings 21 are provided to prevent the working fluid reaching
and leaking between screw 22 and nut 23 to atmosphere. For valves
pre-set for a given working pressure, i.e. a given spring 95 tension,
these sealing rings are not necessary, since the extension sleeve 25
can then be closed by a solid cap external to the screw for extending
the spring.
The use and operation of the valve just described will be understood
by reference to Figure IV, which shows the valve with its inlet
connection 11 communicating with the ring main 40 of a multiple burner
liquid fuel system comprising also a pump 41, burners 42 and a 10
supply tank 43. The inlet connection 11 of the valve communicates with
the delivery side of the pump 41 and the burners 42; the outlet
connection 12 communicates with the inlet side of the pump 41. After
starting the pump 111 41, fuel will reach the port 8 which is closed
by piston 1. Some of the fuel, however, con flow through passage 13 to
the underside of the piston 1 and will exert a pressure on it.
This pressure will increase as the speed of the 11 pump 41 increases
until it exerts on the piston 1 a fcrce -eoual to that exerted by the
spring 17. The piston will then move longitudinally against the force
imposed by the spring 17 until the annular channel 6 overlaps ports 8
12( and 10. The fuel can then flow through port 8, channel 6 and port
10 to outlet 12.
The overlap of channel 6 and port 8 will automatically adjust itself
to pass the quantity of flow in excess of that required by the 125
burners 42 while maintaining substantially constant pressure at the
burners 42. The liquid pressure on the top side of the piston 1 as
seen in Figure 1 will be that which exists in the outlet passage 12
since passage 9 con- 13C 780,198 nects the two. In other words, the
passage 9 prevents any fuel from the inlet connection 11, which may
have leaked past the piston 1 into the end cap 16, from accumulating

5. in the end cap and exerting a pressure on the piston 1.
The distribution of liquid pressure within the channel 6 will vary
with the quantity of liquid passing but, since it acts equally on the
top and bottom walls of the channel, there can be no resultant force
on the piston 1 as a whole.
With this arrangement, the difference between the pressure P2 and the
pressure P, shown by gauges G2 and G1 respectively will be
substantially constant and the supply pressure to each of the burners
42 will be substantially constant, irrespective of the number of
burners in use.
Figure IV also indicates diagrammatically an alternative arrangement
in which the passages 9 and 13 are blocked and the spaces below and
above the piston 1 are in communication with conduits 44 and 45
respectively. Conduit 44 communicates with a point on the ring main
between the burners 42, and conduit 45 leads back to the supply tank
43. With this arrangement, the difference between the pressure P4 and
the pressure P, shown by the gauges G4 and G, respectively, remains
substantially constant and, here again, the supply pressure to each of
the burners 42 will be substantially constant irrespective of the
number of burners in use. One advantage of this alternative
arrangement is that it allows a pressure P4 to be established at or
near any particular burner.
Turning now to Figure III, the valve shown therein is constructed to
operate as a pressure reducing valve and differs from the valve shown
in Figures I and II in that there is no passage 13 providing
communication between the inlet connection 11 and the lower side of
the piston 1 and no passage 9 providing communication between the
outlet connection 12 and the upper sidet of the piston 1. There is,
however, a passage 48 which provides communication between the outlet
connection 12 and the upper side of the piston 1. There is, tion of
the channel 6 in the piston 1 is so arranged that under the effect of
the spring tension and when there is no fluid pressure, channel 6 and
ports 8 and 10 are in register.
Any fluid pressure subsequently developed on the underside of the
piston 1 tends to decrease the passage area through the valve. A
connection 31 is provided to remove any liquid which leaks past the
walls of the piston 1 and also, by taking a pipe therefrom to a
selected point in a system, to establish a particular liquid pressure
on the top of the piston 1.
Alternatively, the passage 48 may be blocked and the lower side of the
piston 1 put into communication with any desired point of the system
of which the valve forms a part.
The use of the valve shown in Figure III is exemplified in the
multiple burner liquid fuel system shown in Figure V; where the valve

6. is shown as a pressure reducing valve controlling the pressure of fuel
which is fed to it from a supply tank 43 via a conduit 50 which
includes a pump 41 by-passed by a surplus 70 type control valve 49
which may be of the type shown in Figure I, although it is generally
satisfactory to employ a less accurate type of pressure controlling
valve. Fuel flows from the reducing valve to a number of burners 42 75
through a conduit 40. Leakage from the end cap 16 is returned to the
tank 43 via a conduit 51.
When the system is in operation, valve 49 is set to give at gauge G,
any pressure P1 80 greater than the required pressure P. (gauge G,) at
the burner 42. The pressure reducing valve functions to maintain a
substantially constant difference between the pressure P2 shown on
gauge G, and the pressure P, shown 85 on gauge G,.
The pressure reducing valve has its most useful application where
there is an existing fluid supply at a pressure greater than that
required. By taking a branch off this supply 90 to a pressure reducing
valve, the pressure may be reduced to any required value, this value
being constant and independent of any pressure variations which may
take place in the existing supply. 95 In an alternative arrangement,
where the passage 48 is blocked and the sleeve 25 is in communication
with a point between the burners 42, by means of a conduit 44, a
substantially constant pressure is maintained 100 between the pressure
P4 shown on gauge G4 and the pressure P, shown on gauge G,.
In the case of valves shown in Figures I, II and III, change of piston
position to accommodate changes in excess pump delivery 105 will alter
the extension of the spring 17 and thus the load on the piston I. The
controlled pressure will alter accordingly. By using a spring in
tension, there is no theoretical limit to the length of spring which
may be used. In 110 this way, changes in the position of the piston 1
can be made to have as little effect as desired.
In practice, quite moderate spring lengths, e.g.
between 3 and 6 inches for the size of valve shown in Figure I, will
limit pressure variations from this cause to 1 or 2 per cent. When
using a spring in compression, care must always be taken to avoid
buckling of the spring to the extent where it touches some
neighbouring structure such as the wall of its container which gives
rise to frictional restraints on the spring movements and leads to
erratic pressure control. The avoidance of this defect involves the
use of relatively short helical springs and/or wide spring containers.
Both 125 of these features are undesirable and hence tension springs
are preferred.
When using a valve according to the present invention for controlling
the pressure of a stream of gas which term is taken to include 130
780,198 steam and other vapours, it is sometimes permissible to

7. provide only an escape vent to deal with leakage past the piston 1.
Thus when air or steam are passing through the valve, the passage 9 of
Figure I or the passage 31 of Figure III may be replaced by a simple
vent in the end cap 16.
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