Improvements in or relating to Valves.
Year: 1898

page_text: Date of Application, 26th Mar., 1898-Accepted, 26th Apr., 1899
COMIDELE DIFCITICATION.
Improvements in or relating to Valves.
I, PAOLO MARTINELLI, Managing Director of the Societe pour l'exploitation de
decouvertes Industrielles, Naples, in the Kingdom of Italy, do hereby declare
the nature of this invention and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement:
This invention relates to a valve which automatically closes when the fluid in
the conduit to which it is applied escapes, and is represented by way of example in
various forms and positions in the accompanying drawings in vertical section.
The device consists of two cylindrical bodies A B, and CD (Fig. 6) which intersect.
The part A B has two flanges one A connected to the pine through which the fluid
escapes, and the other B connected to the pipe through which the fluid enters.
The other part CD has a flange C to which is secured a cover E and a flange F, to
which is secured a bracket G supporting the usual mechanism for
operating the spindle of the valve. At the intersection of the two
parts there is a conical portion H forming a hollow space I. In the
part AB there is an enlarged portion K which forms a space L. The fluid
enters through B, passes into the chamber I then through the annular opening M,
into the space L and out through A. In the part CD there is a valve-piston m
seating in M. This valve fits loosely in the parts CD so that the fluid entering
under pressure through a small port o enters the chamber q and exercises pressure
on the face of the valve opposite to the seat M (Fig. 6). The spindle of the valve
is not rigidly secured to the valve, so that the latter can slide upon it, as may be
seen from the drawing. This spindle is however provided with a head by means
of which it is possible by turning the hand wheel to force the valve against its
seat M as shown in Fig. 2, or to lower said valve as shown in Fig. 1, and leave
it free in its ascending closing movement by replacing the spindle in such position
so that its pointer coincides with the central notch of the support as shown in
Fig. 1. The valve m is thus free in its movement so that it can close the
opening M. If now there is escape of compressed fluid in the conduit connected
to A, this fluid attains an abnormal velocity in the chamber L, in consequence of
which there is a great loss of pressure in the ratio of the square of the velocity under
the face of the valve m, so that the difference of pressure on both sides exceeds the
weight of the valve and forces it against its seat, as in Fig. 3 thus closing the
valve. If it is desired to secure the valve in this position, it is sufficient to turn the
band wheel so as to bring the head r up against the top of the valve (as shown
in Fig. 6).
When the valve is to be opened, the spindle is turned until its head r pushes the
valve down as shown in Fig. 4, and then the spindle is returned in such a position
that its index or pointer coincides with the notch in the centre of the bracket.
In this position shown in Fig. 4 the valve is fully open, the spindle having been
screwed down and its head having pressed the valve away from its seating M, after
which the spindle will be operated in the opposite direction to render the valve
independent of it as already explained. The fluid enters at B flows around the
valve casing and over the top of the valve through the chambers D, L and outlet A.

page_text: Should the pipe burst on the side A of the valve the suction action set up will
draw the valve to its seat and the fluid on the inlet side will pass through
the passage o and press against the rear face of the valve and so hold it firmly
closed as shown in Fig. 3. The valve may be made to react even if there is an
escape the size of which is only 100 of the area of the valve. This is effected by
bringing the valve nearer to its seat by means of its spindle. When the valve is
totally closed, as in Fig. 2, all the pressure of the fluid coming through B acts
upon one side of it and nothing or only atmospheric pressure on the other face
nearest to the annular seat. It then it is desired to open the valve, a strong
pressure must be exercised on it by means of the hand wheel and spindle which
must be very strong. To avoid this and to avoid a sudden opening of the valve
which would assist priming and cause too great an expansion, the head r of the
spindle is utilised by making it of conical shape so that it closes the annular opening t
(Fig. 2) round the spindle in an air-tight manner and there is also made an
opening or openings n in the valve of dimensions to suit the size of the pipe,
through which openings all the fluid enters the interior of the valve when the
spindle is lowered and passes through the annular opening into the tube A
(Fig. 5) recesses or grooves being provided in the end of the spindle for this
purpose. Thus after a certain time the pipe A will gradually become filled with
Huid having the same pressure as at B. Owing to the pressure being thus
balanced, it will be very easy to open the valve, and it will even open automatically
by reason of its weight. The spindle and hand wheel of the valve may be in any
position with its automatic working being at all modified.
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:-
1. A cut off valve for steam pipes comprising a piston arranged in a chamber
connected to and communicating with the steam pipe, whereby the valve is
kept open under normal conditions by the pressure of steam on one face of the valve
being greater than that on the other face, but should the steam pipe. burst the
pressure will become lower on that side of the valve and the greater pressure of
steam on the other side will cause the valve to close automatically substantially as
described.
2. The combination and arrangement of parts constituting the complete cut
off valve for steam generators substantially as described or illustrated in Figure 1 or
in Figure 2 or in Figure 3 or in Figure 4 or in Figure 5 or in Figure 6 of the
accompanying drawings.
Dated this 26th day of March 1898