IMPROVEMENTS IN SAFETY VALVES
Year: 1874

page_text: PROVISIONAL SPECIFICATION left by John Radford at the Office of
the Commissioners of Patents, with his Petition, on the 10th January
1874.
I, JOHN RADFORD, of the Central Brass Works, Thornton Road,
Bradford, in the County of York, Brassfounder, do hereby declare the
nature of the said Invention for "IMPROVEMENTS IN SAFETY VALVES," to be
as follows, that is to say :-
My Invention relates to employing an auxiliary valve and disk, to.
which is fitted a weight for the purpose of keeping the required pressure
in the boiler or steam generator. For this purpose I construct my
improved safety valve with an outside cylindrical box, in which is fitted.
a main valve having a four ribbed stem working in a bush. The top
part of this box is made larger in diameter than the bottom part, and
the lid of the main valve fits truly in the top part of the box. Under-
neath the seat of the main valve is formed an opening, allowing the
steam coming through the bottom part of the valve box to pass and
travel through a steam passage to a round disk fitted in the top part of
the valve box. In this disk is formed an opening or chamber com-
municating with the steam passage. In the disk is fitted an auxiliary
valve seat, in which fits the auxiliary valve, which is formed on the end

page_text: of a stud. On the top of this stud is formed a collar fitting a top
opening in the disk, and on the top of the collar is formed a spindle,
on which is placed a weight to regulate the pressure.
The steam passing from the boiler or steam generator passes through
the steam passage formed under the main valve seat, then through the
passage made on the side of the cylindrical box, on through the opening
or chamber in the disk, and through the auxiliary valve, arriving in a
chamber formed between the disk and the top of the main valve, pressing
on the top of the main valve, keeping it shut.
Should the pressure in the boiler or steam generator exceed the
working pressure it will lift up the weight fitted on the spindle by
means of the auxiliary valve closing, and the main valve will open,
allowing the steam to escape through an escape pipe cast on the safety
valve box. Directly the pressure falls to the working pressure the
weight will fall and open the auxiliary valve and close the main
valve.
In the bottom part of the cylindrical valve box is cast or fitted a rib,
in which is fitted a tap or valve or their equivalent. To the tap or valve
is fixed a spiral grooved stem, to which is attached a spiral rod having a
float at the extremity. The tap or valve communicates with a passage
cast or formed on the side of the valve box, and communicates with the
lid of the safety valve box, in which is fitted a steam whistle. Should
the water fall below the required working waterline it will cause the
float to drop and turn the spiral rod and open the tap or valve, allowing
steam to escape through a passage made on the side of the safety valve 1
box and enter the chamber under the valve box cover and blow the
whistle, giving an alarm.
Instead of a float I can use a fusible plug, which I place in the stopper
of the whistle.
I also use a tap fitted to the side of the top valve box communicating
with the opening or chamber of the disk, and having a passage com-
municating with the escape pipe. This tap is for the purpose of blowing
off steam when under pressure, and when required to do so.