Im- PROVEMENTS IN SAFETY AND RELIEF VALVES."
Year: 1873

page_text: LETTERS PATENT to John William Melling, of Birkett Bank, Wigan,
in the County of Lancaster, Engineer, for the Invention of "Im-
PROVEMENTS IN SAFETY AND RELIEF VALVES."

page_text: Now my Invention consists in obviating the above defects by making
the valve and seat with two faces, and by exposing only a part of the
area of the valve to the pressure of the steam when the valve is closed,
but when the blowing-off point is reached and the valve is slightly
raised the steam escapes in the ordinary way through one of the faces
and is admitted under the other face and to the other portion of the
valve, thus acting on a greater area. By this means the valve is raised
to the desired height against the increasing resistance of the spring,
springs, or weight.
The steam that is admitted under the second portion of the valvo is 1
allowed to escape through a hole in the valve; this hole as well as the
area of the second portion of the valve is proportioned to suit the
pressure of the steam, the height to which it is desired the valve shall be
raised, and the mode of loading.
Or instead of steam being admitted under a face and to a part of the
valve not exposed to pressure when the valve is closed, as above
described, the steam may be allowed to escape under a face from the
upper part of the valve on which it was pressing to keep the valve
closed, and thus allow the steam underneath to raise the valve more
freely. The steam in this case is supplied to the upper part of the valve
through a hole in it that is proportioned as before.
The valve may have any desired number of faces for the escape of
steam; or the compensating portion may be detached and act through a
lever or other connection on the main portion of the valve.

page_text: Lord One thousand eight hundred and seventy-three, in the thirty-
fourth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said John William Melling, Her special
licence that I, the said John William Melling, my executors, adminis-
trators, and assigns, or such others as I, the said John William Melling,
my executors, administrators, and assigns, should at any time agree with,
and no others, from time to time and at all times thereafter during the
term therein expressed, should and lawfully might make, use, exercise,
and vend, within the United Kingdom of Great Britain and Ireland, the
Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN
SAFETY AND RELIEF VALVES," upon the condition (amongst others) that I,
the said John William Melling, my executors or administrators, by an
instrument in writing under my, or their, or one of their hands and
seals, should particularly describe and ascertain the nature of the said
Invention, and in what manner the same was to be performed, and cause
the same to be filed in the Great Seal Patent Office within six calendar
months next and immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said John William Melling, do hereby
declare the nature of my said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and
by the following statement (that is to say) :-
These improvements are for the purpose of increasing the efficiency of
safety and relief valves.
In ordinary safety valves the lift, and consequently the orifice for the
escape of steam or other fluid, is very limited, more particularly with
high pressures.
Now my Invention consists in obviating the above defects by making
the valve and seat with two or more faces, and by exposing only a part
of the area of the area of the valve to the pressure of the steam when the
valve is closed, but when the blowing-off point is reached and the valve is
slightly raised the steam escapes in the ordinary way through one of the
faces and is admitted under the other face and to another portion of the
valve, thus acting on a greater area. By this means the valve is raised
to the desired height against the resistance of the weight, or against the
increasing resistance of the spring or springs, and notwithstanding
the diminished pressure under the valve near to the escaping orifice.

page_text: through the narrow orifice f and through the hole g. By contracting
the orifice at the steam that passes through the face a³ is made to assist
in raising the valve earlier than would be the case if the steam were
allowed to escape freely by the hole g. As the valve rises the orifice f
widens, but as the face a³ is larger than the said orifice it soon supplies
steam faster than the orifice over the collar f¹ can discharge it; the
pressure under e then increases so as to raise the valve to a height
depending on the mode of loading the proportion of the part e to that
of d which is the portion of the valve exposed to lifting pressure when
closed, and the area of the hole g.
If the valve is to be loaded by dead weight or a weighted lever the
part e is not required to be so large as when a spring or springs are
employed, because the dead weight offers a constant resistance, while
that of the springs increases. Also when the valve commences to blow
off it may be caused to rise to its full height sooner or later by suitably
proportioning the diameter of the collar f¹ and the width of the orifice f.
In Figs. 3 and 4 the same principle is carried out. When the blowing-
off point is reached the steam that passes between the faces a³, 6³, into
the space e has to pass through the orifice fand the annular hole g
surrounding the spindle of the valve A, the spindle is attached to the
valve by the cross bar shewn in the plan. A groove or grooves are cut
in the spindle to allow steam to get freely under it to help to raise the
valve. In smaller valves of this kind holes are drilled in the solid top
as substitues for the annular hole g.
In Fig. 5 are shewn two kinds of valves loaded with the same spring.
The valvo A is the same as Fig. 1, with the addition of the central
collar i, the object of which is for the purpose of contracting the area of
the hole through which the steam escapes when the valve reaches a
certain height. By this means the steam is retained at a higher pressure
under the part e, and consequently is more effective for raising the valve.
The collars f¹ and i may be made adjustable by screwing them into the
boss of the seating B, or otherwise. The valve A¹ is a modification of
Fig. 3 and 4, and allows a greater area for the approach of the steam to
the faces a¹, a³, when blowing off; it has also an additional collar i,
shewn for the purpose before mentioned. The spring / which acts on
the lever is shewn as adjustable by having its lower end passing

page_text: through a loop that fits in the fork or standard C, and it has two
shoulders on which the nut m bears; this nut screws on the bottom of
the standard and has three lugs, each with a hole in it, so that if desired
by passing the pin n through one of them and the hole in the lug the
nut may
be secured by a lock, as shewn.
Figs. 6 and 7 represent a modification of Figs. 1 and 2, with the
collar shewn on the valve; this valve is guided and weighted by
having its central spindle passing through the guide o and fitted with
the nut a³ on which the collar p bears, on which collar are two V pieces
supporting the cross bar to which the springs k are attached. On the
guide o is centred the lever q for the purpose of raising the valve from
its seat by hand; the lever is made in two pieces, the outer end that
passes through the casing screws into the other part so that it can readily
be removed. When the casing is placed over and secured by locks, or
otherwise, the valve is completely secured from being tampered with as.
the broad head of the lever q inside completely covers the hole through
which the screwed part of the lever passes, and the plater under the
discharge orifice prevents any interference from above.
The valve is shown partly raised; when rising higher it contracts the
orifice for the steam escaping between the inside of the valve and the 2
collar i.
In Fig. 8 is shewn another mode of regulating the exit of the steam
from the part e. 8 is a valve fitting loosely on and guided by the
weighting screw t, and held down by the spring u; the annular orifice
over which the valve rests is crossed by four arms. When the steam 2
enters the part e it is there retained by the spring u and valves until the
desired pressure is reached when the spring allows the steam to escape
at a suitable rate.
Having thus stated the nature of my Invention and described several
modes of performing the same I wish to observe that I do not intend to a
limit myself to the details given, and that I make no claim to an annular
or double faced valve, as valves with two or more faces have before
been used; but what I claim is,―
First. The modes of constructing valves, as shewn and described,
whereby the steam in escaping assists in holding the valve open to 8
facilitate the discharge of the steam.

page_text: And, Secondly. In the use of a regulator to control the size of the orifice
for the discharge of the steam and the area against which the escaping
steam first acts, as shewn and described.
In witness whereof, I, the said John William Melling, have hereto
set my hand and seal, this Fourth day of May, One thousand eight
hundred and seventy-four.