IMPROVEMENTS IN DIMINISHING AND AIR VALVES
Year: 1877

page_text: PROVISIONAL SPECIFICATION left by William Hanson at the Office of the
Cominissioners of Patents on the 16th July 1877.
WILLIAM HANSON, Engineer and Machine Maker, of Bradford, in the County of
York. "IMPROVEMENTS IN DIMINISHING AND AIR VALVES."
My Invention relates to diminishing or reducing the pressure of steam, and to
closing air valves by means of mercury. For this purpose I construct my improved
diminishing valve with a case, in which is fitted a pipe, and to which is fitted an
equilibrium valve of a "double beat" form; the top of the valves is connected to
a lug formed on the base of a circular cup, in which mercury is placed; on the out-
side, and near the top of the cup, are fitted swivel joints similar to the bearers of a
pair of scales; these joints oscillate on a ring formed on the end of the equilibrium
valve lever; inside the cup is placed a small pipe which extends through the lid of
the valve chamber or case a sufficient height to equalize the weight of mercury with
the pressure reduced; the pipe passes through a gland or stuffing box fitted on the
top of the valve case, and on the top of the pipe is fitted a closed cup to receive the
mercury forced up the pipe; the fulcrum of the equilibrium valve lever works on
swivel joints, which are fitted or formed on the lever, and oscillate on brackets cast
in the inside chamber of the valve case; on the other end of the equilibrium valve
lever is fitted a weight. An increase of pressure within the valve chamber or case
increases the pressure on the surface of the mercury contained in the cup, causing
the mercury to rise in the pipe and reducing the weight of the cup on the equi-
librium valve lever until it equals the weight of the reduced pressure; the weight
on the lever being reduced causes the balance weight to fall and close the equi-
librium valve; when the pressure decreases the mercury falls down the pipe into
the cup, pressing down the lever and opening the equilibrium valve; a safety valve
is fitted on the top of the valve case.
The air valve is principally employed on steam traps, but may be used for other
purposes. The top of the steam trap is made with a circular chamber constructed
with a top flange in which is screwed the top part of a circular cup which is formed
at the base with a recessed chamber to hold mercury. The top part of the cup is
made with an opening in which works a vulcanite india-rubber spindle, having on
the top a small valve which works in a seat formed in a cup or bonnet fitted on the

page_text: top circular chamber of the steam trap. In the top part of the mercury cup are
formed air holes which open in the circular top chamber of the steam trap, and the
inlet steam pipe is fitted on the side of the circular chamber.
The small valve fitted on the vulcanite india-rubber spindle remains open until
such time as there is no pressure or steam in the trap; the air is discharged through 5
the air openings; directly the air is expelled the steam enters the trap, heating the
mercury in the cup, which expands and lifts up the vulcanite india-rubber spindle
and valve, closing it. When the steam is turned off the mercury falls and opens
the air valve.