Improvements in Balanced Valves.
Year: 1892

page_text: Date of Application, 27th June, 1892
Complete Specification Left, 24th Mar., 1893-Accepted, 20th May, 1893
PROVISIONAL
SPECIFICATION.
Improvements in Balanced Valves.
I THOMAS WALTER BARBER of 5 Page Street, Westminster, in the County
of Middlesex, Engineer do hereby declare the nature of my said invention to be
as follows:-
The object of this invention is to so construct the valve proper & valve-box of
that kind of valve usually known as a "D slide," or its inodifications; that the
pressure of the motor fluid underneath the valve, in a cavity formed in the valve
for that purpose, shall be overbalanced by the pressure of the fluid on the outside
of the valve, in the box, to an extent just sufficient to secure its proper working.
To obtain this end, I use a valve of the above mentioned description, to which
an additional cover is added, so as to form a cavity enveloping the whole or part of
the valve proper, the said cavity being between the valve proper & the said cover.
Into this cavity the motor fluid is first introduced, through a port or ports suitably
located in the valve face of the box. The valve box is a closed chamber & has no
connection with the motor fluid supply, or any other source or means of pressure
whatever, save through the aforesaid port or ports in the valve face, covered by the
valve. Ordinary drain cocks may, of course, be attached, to draw off condensed
vapour in the case of steam valves &c.
The action of the valve is as follows:-When the pressure fluid is admitted
under the valve into the cavity of the valve, it instantaneously forces the valve off
its face & escapes into the closed valve box. Now the external area of the valve
with its cover is very much in excess of the internal area exposed to pressure &
consequently, a much less pressure in the box suffices to balance the pressure of the
fluid in the valve cavity. This lower pressure is almost instantaneously attained in
the box & the valve is forced back to its seat, being just balanced between the
supply pressure in the cavity & the escaped pressure in the box. No more fluid
(or pressure) will leak under the valve face until the pressure in the box is lowered
so much as to allow the internal pressure to once more lift the valve & so restore
the necessary equilibrium.
This action is quite automatic & is absolutely independent of any artificially
created pressures, or mechanical contrivances other than those herein described.
The ordinary mechanisms for controlling the valve, as regards its proper uses,
are retained without modification, save that, as the valve works with little or no
friction, they may be made of correspondingly less strength.
When motor fluids are in use, which have no inherent elasticity, such as water or
oil, it is desirable to add an air chamber to the valve box, to obtain the necessary
elasticity & variation of pressures.
60
For the purposes of this description I have used the words "motor fluid,"
pressure fluid & "pressure
which may be taken as having practically the same
meaning, as far as their application to this Specification is concerned.
27th June 1892.

page_text: COMPLETE SPECIFICATION.
Improvements in Balanced Valves.
I, THOMAS WALTER BARBER, Engineer, of 5 Page Street, Westminster, in
the County of Middlesex 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:-
The object of this invention is to so construct the valve proper & valve box of
that kind of valve usually known as a D slide," or its modifications, that the
pressure of the motor fluid underneath the valve, in a cavity formed in the valve
for that purpose, shall be balanced by the pressure of the fluid on the outside of
the valve, in the box, to an extent just sufficient to secure its proper working.
To obtain this end, I use a valve of the above description, to which an additional
cover is attached, so as to form a cavity enveloping the whole or part of the valve
proper the said cavity being between the valve proper & the said cover.
In the accompanying drawing,
Figures 1; 2; 4; 7 & 8 shew valves E. of this description with an additional
cavity A. formed round them, as described. This cavity may be continued over
the top of the valve proper, or may, on the contrary, even be discontinued on one
or more sides of the valve, if desired.
Into this cavity A. Figures 1; 2 & 4; the motor fluid is first introduced, thro
a port B. or ports, suitably located in the valve face C. of the box D. The valve
box D. is a closed chamber & has no connections with the motor fluid supply or
any other source or means of pressure whatever, save through the aforesaid port B
or ports in the valve face C, covered by the valve E.
The action of the valve is as follows:-When the pressure fluid is admitted under
the valve, into the cavity A. of the valve, through the port B. it instantaucously
forces the valve off its face & escapes into the closed valve box D.
Now the
external area of the valve E. with its cover F. is in excess of the internal area A.
exposed to pressure & consequently, a less pressure in the box D., acting on the
whole external area, suffices to balance the pressure of the fluid, acting only in the
valve cavity A. This lower pressure is almost instantaneously attained in the box
& the valve is forced back to its seat, being balanced between the. supply pressure
in the cavity A. & the escaped pressure in the box D. No more fluid (or pressure)
will leak under the valve face C. until the pressure in the box is lowered so much
as to allow the internal pressure to once more lift the valve & so restore the
equilibrium.
This action is quite automatic & is absolutely independent of any artificially
created pressures or mechanical contrivances, other than those herein described.
The ordinary mechanisms for the control of the valve, as regards its proper uses,
are retained without modification, save that, as the valve works with little or no
friction, they may be made of correspondingly less strength.
When motor fluids are in use which have no inherent elasticity, such as water or
oil, it is desirable to add an air chamber Figure 5; or an elastic piston, similar in
construction to that shewn in Figure 6; or any such suitable compressible device,
to the valve box D., in order to obtain the necessary elasticity & variation of
pressures.
Figures 7. & 8. are examples of the application of this invention to modifications
of the "D slide," ei. Figure 7. to a double ported valve & Figure 8. to an
expansion slide.
:-
For the purposes of this description I have used the words, fluid; motor fluid
pressure fluid & pressure; which may be taken as having practically the same
meaning, as far as their application to this Specification is concerned.

page_text: Having now particularly described & ascertained the nature of my said inven--
tion, & in what manner the same is to be performed, I declare that what I
claim is:-
1st. The combination of a valve, constructed with a cavity or cavities as
hereinbefore described; with a closed valve box, so arranged, that the pressure-
fluid escaping from underneath the valve, shall enter the box & create a counter
pressure & equilibrium.
2nd. The combination with the above described valve & box, of any suitable &
customary device, such as those herein described; to obtain the necessary variation
of pressure, in the case of non-elastic pressure fluids.
3rd. The addition of the cavity & the construction of a closed valve box as
herein described, to any of the forms of slide valves, such as are known as
modifications of the "D slide" & of which two examples are given in
Figures 7 & 8.
T. W. BARBER..