IMPROVEMENTS IN GAS METERS
Year: 1850

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HENRY
MEDHURST, Engineer, in the employ of Mess" Shears and Sons, of Bankside,
Southwark, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of the United Kingdom of Great
Britain and Ireland, bearing date at Westminster, the Twelfth day of
November, One thousand eight hundred and fifty, in the fourteenth year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said Henry Medhurst, my exors, admors, and assigns, Her especial
license, full power, sole privilege and authority, that I, the said Henry Med-
hurst, my exors; adñiors, and assigns, or such others as I, the said Henry
Medhurst, my exors, adors, or assigns, should at any time agree with, and
no others, from time to time and at all times during the term of years therein
expressed, should and lawfully might make, use, exercise, and vend, within
England, Wales, and the Town of Berwick-upon-Tweed, my Invention of
"IMPROVEMENTS IN GAS METERS;" in which said Letters Patent is contained a
proviso that I, the said Henry' Medhurst, shall cause a particular description
of the nature of my said Invention, and in what manner the same is to be
performed, by an instrument in writing under my hand and seal, to be inrolled
in Her Majesty's High Court of Chancery within six calendar months. next
and immediately after the date of the said in part recited Letters Patent, as in
and by the same, reference being thereunto had, will more fully and at large
appear.

page_text: KOW KNOW YE, that in compliance-with--the said. proviso, I, the said
Henry. Medhurst, do hereby declare that the nature of my said Invention,
and in what manner the same is to be performed, are fully described and
ascertained in and by the following description thereof, reference being had
to the Drawings hereunto annexed, and to the figures and letters marked
thereon; that is to say :-
My improvements consist,-First, in the use and application to dry gas meters
of conical seat valves, with one or more passages to admit and discharge the gas
to and from the different compartments of gas meters. I cause these valves to
have a rotary
or partially rotative motion in their seats; and I so arrange
them that the valves themselves (excepting their faces), and the whole of the
machinery for working them, is not in contact with the gas, by which I avoid
corrosion of the parts employed; encreased durability, and ready access in case
of repair. The construction of meter we prefer when using such valves consists
of a cylindrical case (A, Figure 1, 2, 3, 4, 5, divided into two compartments
by the vertical division B, in each of which are placed a diaphragm box C,
forming the meter into four compartments, W, X, Y and Z. The lower part
of the case A, containing the working diaphragms E, F, is divided from the
upper by the valve plate D. The flexible diaphragms- E are fastened in
grooves to the outer edges of the diaphragm boxes C, their inner edges being
fastened in like manner to the shield or inflexible part of the diaphragm F,
to which the vertical shafts G, G, are attached. These diaphragms E, F, are
made to.vibrate with the shafts G, G, by the alternate action of the gas on
either side of them, and the vertical shafts are passed through stuffing boxes
a, a, in the valve plate D, to give the necessary movements to the valves
H, H, and the index J. On the top of the vertical shafts G, G, are fastened
levers b, b, at right angles with each other, with connecting rods c, c, acting
on a crank d, which is revolved by the vibratory action of the levers b, b.
This crank d drives two others on the same axle e, e, with connecting rods
ff, attached to arms 9, g, on the top of the cone valve H, H, which conse-
quently have a partial rotative motion in their seats to admit and discharge the
gas to the different compartments of the meter, as may be necessary. The
index J is worked by a screw h revolving with the crank axle e, e, and
works into a toothed wheel on the spindle j, communicating with the train
of wheels in the index. In consequence of the peculiar form of the screw
h, as was described in a former Patent, it matters not which way the
meter is worked, as the gas may be admitted at either the inlet or outlet
pipe, without affecting the registration, as the index always advances. The
action of the meter is as follows:-Gas is introduced at the inlet K, and passes

page_text: along the passages L, L, to the inlet ports of the valves a", a", Figures 2
and 6, then passes in the direction of the arrows (as shewn by the valves
drawn in section, Figure 6), to act upon the diaphragms. Suppose that gas
has been allowed to fill and extend the diaphragm to its limit, as shewn in the
plan of the left-hand diaphragm box (compartment W), the valve H then
alters its position, and allows the gas which had extended the diaphragm to its
limit to pass out into the outlet pipe M, through the pipe 6", by which it had
before entered; at the same time gas is passing from the inlet pipe k into the
external chamber or compartment Y, and forcing the diaphragm back to its
opposite limit (as shewn by the dotted lines. It will, therefore, easily be
seen, that the quantity of gas passing through the meter at one revolution of
the crank d is equal to four times the space occupied in the traverse of one
diaphragm from limit to limit, that is to say, twice for each diaphragm, both
being in action at the same time, but in different positions. The whole of the
gas passes out of the meter at the outlet pipe O to the burners.
My second improvement consists in the introduction to wet gas meters of a
cylindrical vessel to receive the float, the vessel having a small perforation
near the bottom, the use of which is, that upon any sudden increase of pressure
the valve attached to the float by the wire will not suddenly descend and close
as in ordinary meters, causing a vibration in the light, and in many instances
closing the valve, thereby shutting the gas entirely off, although the meter
may be properly charged with water. The cause of this will be better under-
stood by the following explanation:-In ordinary meters, when the gas is
turned into the meter, the water in the square box in front of the meter is
suddenly driven or forced into the compartment containing the wheel or drum,
in consequence of which the float descends in equal proportion, thereby
bringing the valve attached thereto so close upon the seating as to cause the
float to vibrate, causing thereby an unequal pressure in the meter, and conse-
quent unsteadiness of light. To prevent this I introduce the cylindrical vessel
C, Figures 8 and 9, containing the float B (the vessel C is made in any form
to suit the shape of the float), having the bottom F soldered into it. Near the
bottom F is a small orifice E to admit water into or from the square box I,
the use of which is, that if the pressure is suddenly augmented by any means,
the water in the square box I will flow through the centre opening H into the
5 compartment containing the drum wheel, as usual, but the water contained in
the vessel C will maintain nearly its original level, and then gradually descend,
taking the float B with it until the cone valve A sufficiently diminishes the orifice
of the seating G to balance the external pressure, thereby causing always an
equal pressure in the meter, and steady lights.