IMPROVEMENTS IN SAFETY VALVES
Year: 1884

page_text: We WILLIAM NEWZAM NICHOLSON and ARTHUR THOMAS ALLCOCK, both of
Newark upon Trent in the County of Nottingham, Mechanical Engineers, do
hereby declare the nature of our Invention for IMPROVEMENTS IN SAFETY VALVES
to be as follows:-
Our Invention has for its object Improvements in Safety Valves and relates
especially to those valves, where, if any additional weight is placed upon them
beyond that at which they are set to blow off, a secondary valve will be opened
and steam discharged until the overweight is taken off; and for which Letters
Patent dated the First day of March One thousand eight hundred and eighty four
and numbered Four thousand two hundred and eleven were granted unto us.
In the above recited Letters Patent we describe a compound valve made up of an
annular valve opening outwards and an internal central valve opening inwards and
closing the central hole of the annular valve.
The first part of our Invention consists of a method of balancing the steam
pressure upon the internal central valve, to do so, we form the main annular valve
with two chambers on its upper side, one above the other. The uppermost of these
two chambers is in communication with the steam in the Boiler by means of one or
more side passages made in the body of the valve, and the lower chamber is in free
communication with the atmosphere. In lieu of the inner central valve having
only one disc opening inwards to the steam chamber we provide it with an
additional one openining downwards to the atmosphere in the lower chamber, and
80 constituting what is known as an equilibrium valve. The spindle of this
valve passes upwards through the steam chamber of the annular valve and is
connected to it by the arrangement of an adjustable spiral spring bearing with
its upper end on a collar on the internal central valve spindle and with its lower
end on the top of the main annular valve as described by us in the before recited
Letters Patent. To enable the internal central valve to be passed through the
base of the main annular valve, a circular opening is provided in it and stopped
with a removeable plug. This plug has one or more stops on its upper side which
engage with similar stops formed on the bottom of the internal central valve, so
that when the latter is rotated it will carry the main annular valve with it and
turn it on its seat. The lower side of the plug is provided with feathers or guides
to guide the annular valve on to its seat.

page_text: The second part of our Invention is a further modification and consists of a
prolonged central steam passage attached on the upper side of the main valve
which opens outwards as before described. The upper end of this passage is closed
but steam ports are made in its circumference opening outwards between two valve
seatings, surrounding these seatings and opening downwards is an equilibrium
valve having two internal faces and so closing the steam ports in the circumference
of the central steam passage. This valve is held upwards to its seat by a spiral
spring which surrounds the central steam passage and butts thereon with its lower
end. To hold the compound valve so formed to the seat of the main valve the
load is applied by any of the means in ordinary use, acting on a cap which is
placed on the head of the equilibrium valve. For rotating the valve one or more.
stops are formed on the top of the cover of the central steam passage and engage
with similar stops made on the underside of the cap of the equilibrium valve; so
that by rotating the latter its motion is communicated to the main valve.
Safety valves constructed in accordance with our Invention may be used as Low
Water Indicators by connecting a float in the boiler with a sliding rod or chain to
the weighted end of the lever of the valve, or its equivalent, in such a manner that
when the float rises with high water in the boiler it has no effect upon the lever
but if the water falls below a given level the weight of the descending float will
come upon the lever and open the internal central valve, or its equivalent. Steam
will then be discharged from the boiler until the water has risen again to its
proper lowest level.

page_text: We WILLIAM NEWZAM NICHOLSON and ARTHUR THOMAS ALLCOCK both of
Newark upon Trent in the County of Nottingham, Engineers, do hereby declare
the nature of our Invention for IMPROVEMENTS IN SAFETY VALVES, and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement :—
Our invention has for its object improvements in Safety Valves, and relates
especially to those valves, where, if any additional weight is placed upon them
beyond that at which they are set to blow off, a secondary valve will be opened
and steam discharged until the overweight is taken off, and for which Letters
Patent, dated the first day of March, One thousand eight hundred and eighty
four, and numbered Four thousand two hundred and eleven were granted unto us.
In the above recited Letters Patent we described a compound valve made up of
an annular valve opening outwards and an internal central valve opening inwards
and closing the hole of the annular valve.
Our invention consists of a method of balancing the steam pressure upon the
internal central valve.
In the accompanying sheet of drawings Fig. 1 is a sectional elevation of a
complete valve and Fig 2 is an elevation of the main valve detached.
We form the main annular valve A with two chambers G and G¹ on its upper
side, one above the other. The uppermost of these two chambers G is in
communication with the steam of the Boiler by means of one or more side passages g
made in the body of the main valve A, and the lower chamber G¹ is in free
communication with the atmosphere. Instead of the inner central valve having
only one disc B we provide it with an additional one B¹ opening downwards to
the atmosphere in the lower chamber G¹ and so constituting what is known as an
equilibrium valve. The spindle C of the internal central valve so formed passes
upwards through the steam chamber G and is connected to the main valve A by
the arrangement of an adjustable spiral spring S bearing with its upper end on a
collar D on the internal central valve spindle C, and with its lower end on the top of
the main annular valve A as described by us in the above recited Letters Patent.
To enable the internal central valve to be passed through the base of the main
annular valve A a circular opening is provided in it and stopped with a removeable
plug M. This plug has one or more stops N¹ formed on its upper side which
engage with similar stops N formed on the bottom of the internal central valve B¹,
so that when the latter is rotated by means of its spindle C it will carry the main
annular valve A with it and turn it on its seat a.
The lower side of the plug M is provided with feathers or guides to guide the
main annular valve A on to its seat a.
Figure 3 shows in sectional elevation another method of carrying out our
Invention.
The equilibrium valve B and B is in this case inverted and reversed, being
attached to the main annular valve A by the central steam passage G. The
equilibrium valve seating b and b¹ is held up to the valve B and B' by the spiral

page_text: spring S, which in this case surrounds the steam passage G and is adjustable by
the nut d. The weight to load the main valve A is applied by any of the ordinary
methods to the equilibrium valve seating band 61 acting on its cap C; and should
this weight be in excess of what the spring S is adjusted to carry, it will be
deflected and the equilibrium valve seating b and 61 opened and the steam
discharged.
One or more stops N are formed on the under side of the cap C, which, on being
rotated, come in contact with the corresponding stops N¹ made on the top side of
the equilibrium valve B and B and so rotate it together with the main valve A.
Having now particularly described and ascertained the nature of our said
Invention and in what manner the same is to be performed we declare that what
we claim is
1. The construction of the compound valve A, the internal equilibrium valve
Band B¹ and its spindle C with the spring S or its equivalent, substantially as
shown in Figures 1 and 2, and for the purposes described, or any mere modification
thereof.
2. The employment of one or more stops N and N¹ in combination with the
internal equilibrium valve B and B and the annular valve A, substantially as
shown in Figures 1 and 2, or any mere modification thereof.
3. The construction of the compound valve A the equilibrium valve B, and B¹
with its seating b and b¹ and the spring S or its equivalent, substantially, as shown
in Figure 3, and for the purposes described or any mere modification, thereof.
4. The employment of one or more stops.N and N' in combination with the
cap of the equilibrium valve seating b and b' and the equilibrium valve
B and B¹, substantially as shown in Figure 3 or any mere modification thereof.
Dated 23rd September 1885.