AN IMPROVED LOCKED SAFETY VALVE ARRANGEMENT FOR MARINE AND OTHER PURPOSES
Year: 1873

page_text: PROVISIONAL SPECIFICATION left by Edward John Cowling Welch at
the Office of the Commissioners for Patents, with his Petition, on
the 4th January 1873.
I, EDWARD JOHN COWLING WELCH, of Liverpool, in the County of
Lancaster, Engineer, do hereby declare the nature of the said Invention
for "AN IMPROVED LOCKED SAFETY VALVE ARRANGEMENT FOR MARINE AND
OTHER PURPOSES," to be as follows:-
This Invention consists of a metal chamber at the bottom of which is
the valve seating. Upon the seating rests a valve without any guides
or spindle, and with either a flat or conical seating; just above the valve
is a diaphragm of india-rubber or other flexible material, such as thin
metal plate with annular corrugations; by preference I use india-rubber
with canvass "laid "in it; this allows the india-rubber to be flexible.
without being too elastic. Through the centre of the diaphragm passes
a spindle the bottom end of which is conical and rests in a conical recess
formed in the valve; a nut and washer press the india-rubber diaphragm
against a shoulder formed on the spindle and thus forms a tight joint.
The outer edge of the diaphragm is held fast in a recess in the
flanged joint made with the cover of the chamber, and the spindle

page_text: itself 1s guided through a note Dored in the cover. This spindie
therefore serves to keep the valve on the centre of the seat and has no
guides below the diaphragm. On the upper portion of the cover of the
valve chamber a tall cylindrical chamber is formed in which the spring
is placed; the bottom end of this spring rests upon a circular plate of
rather less diameter than the spring chamber, and which plate has a
hole bored in it to enable it to pass over the valve spindle. This spindle
is of rather increased diameter where it passes through the bore in the
cover so as to give a shoulder both above and below the cover. Against
the lower shoulder the diaphragm is pressed, and on the upper shoulder
the plate upon which the spring bears rests. Upon the top of the spring
a similar plate is placed, but this plate has two lugs projecting from it
and fitting in vertical slots in the spring chamber. Above this is a solid
nut with a screw cut on its periphery, and which runs in a thread cut
on the interior of the upper half of the spring chamber. Through the
centre of this nut the valve spindle passes, the nut thus acting as a
guide for it; the nut however is chiefly intended for adjusting the spring
and thus the pressure on the valve, the two lugs on the upper plate
preventing the spring being injured by being dragged round when the
nut is screwed up or down.
A cover is fastened by what is termed a bayonet joint, or by any
convenient joint to the top of the spring chamber and is secured by a
padlock, thus preventing the adjustment of the valve being tampered
with. A relieving lever passes through the upper portion of the spring
chamber above the adjusting nut and through a slot in the valve spindle,
which lever upon being raised relieves the valve, but being pressed down
comes in contact with an internal stop which prevents it reaching the
bottom end of the slot and putting additional pressure on the valve.
The flange joint on the top of the valve chamber can be fastened by a
separate padlock, and this joint can be opened for repairing the valve
without it being possible to alter or get at the spring adjustment.