MENTS IN METERS FOR GAS, WATER AND OTHER FLUIDS." IMPROVE
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by Wilfrid Airy at the Office of the
Commissioners of Patents on the 7th February 1882.
WILFRID AIRY of Queen Anne's Gate in the City of Westminster.
MENTS IN METERS FOR GAS, WATER AND OTHER FLUIDS."
IMPROVE-
This Invention has for its object improvements in meters for gas, water and other
fluids.
The arrangement of the meter for measuring air gas or other fluid of small
specific gravity by means of a fluid of greater specific gravity shall be first
described.
For the sake of clearness in the description it is assumed that the fluid to be
measured is gas and the heavier fluid water.
The measuring drum of the meter consists of an outer cylinder or envelope
connected by three spiral threads with an inner cylinder or core forming altogether
a short archimedean screw of three threads. The core is hollow and open at the
ends. At each end of the core is rigidly fixed a strong open frame having a central
boss through which the axle of the meter passes and to which it is keyed. The
axle is produced both ways to bearings in which it revolves. The bearings aro
rigidly secured to sides or partitions of the box or case of the meter. To the
entry end of the measuring drum a disc is fitted and is tightly secured all round
at its edge to the edge of the outer envelope of the drum. The disc has a central
hole through which passes freely the supply pipe from the gas main or other source
of supply. At the outlet end of the drum there is no disc or plate and the outer.
envelope ends in a circle passing through the points of the spiral threads. But it
may be found advantageous to close up the outlet end of the drum by a disc or
plate with a central orifice and to allow the gas to escape through the said orifice
or by a bent pipe in the same manner as at the entry end. The revolutions of the
drum are registered by a counter which is connected by a vertical shaft and a
toothed wheel with a worm keyed on to the axle of the meter. At the outlet end
of the meter there is keyed upon the axle a toothed wheel which actuates a small
archimedean screw working in a cistern at the end of the box or case of the meter
separated by a partition from the part of the box in which the drum revolves.
This archimedean screw delivers water from the cistern into the meter part of the
box. A return pipe passes through the partition and has its upper end at the lovel

page_text: of the water on the meter side of the partition. The outlet pipe for the gas after
passing through the drum is connected with the case or box of the meter.
The drum is constructed preferably in metal. The spiral threads are made by
preference of thin sheets of metal in the developable form as originally used for the
construction of archimedean screws by the inventor.
The joints of the outer edges of the threads with the outer envelope must be
nade gas tight. The joints of the inner edges of the threads with the core are also
by preference made gas tight, though this is not necessary if the level of the water
inside the meter be never allowed to fall so low as the top of the core, as ought in
general to be the case. The hollow core is made by preference a tube closed around
the periphery, but in certain cases it might with advantage have a number of holes
cut through it in order to allow of the free passage of water from the inside of the
core to the water surrounding it.
The joint of
The drum may have any number of threads but in general three or four threads
will be sufficient to ensure an equable flow of gas from the meter.
the end disc with the outer envelope must be made gastight.
The action of the meter is as follows:-The meter is placed so that the axis of
the drum is horizontal or nearly so. Water is poured into the box till both the
meter and the space surrounding the meter are filled above the top of the central
orifice in the end disc and above the top of the core. The box is then closed and
made gas tight. Gas is then admitted by the bent supply pipe to the space
between the end disc, and the threads of the drum and it fills such of the spiral
chambers as are above the water level. The spiral threads are made of such length
that when the upper descending edge of the mouth of a spiral chamber is just
immersed in the water at the inlet end of the meter the upper uprising edge of the
mouth of the same chamber at the outlet end of the meter has not risen above the
surface of the water. Consequently as the meter revolves successive spiral
chambers full of gas are poured out at the outlet end of the meter into the space
-surrounding-the-meter,-and-thence pass by the outlet pipe to where the gas is being
used. The total quantity of gas passed through the meter per revolution will be
ascertained by experiment, and will continue constant so long as the water level
remains constant. The number of revolutions will be shown by the counter and
therefore the total volume of gas passed in any given interval will be accurately
ascertained by inspection in the ordinary way. The revolution of the meter is
caused by the pressure of the gas from the supply pipe acting on the inclined
spiral threads; this pressure produces a revolution of the meter whenever gas is
being abstracted through the outlet pipe as the pressure inside the drum is then
greater than the pressure outside.
The quantity of gas that can be passed through the meter in a given time will
depend upon the rate of revolution of the drum and the rate of revolution will
mainly depend upon the rate at which the water can recover its normal level
inside. For as the drum revolves the water occupying the lower part is continually
pushed forwards by the action of the spiral threads from the inlet end towards
the outlet end and is there discharged into the water surrounding the drum.
The meter will only turn so fast as admits of the water supply at the inlet end
being renewed and the water surface inside the drum maintained at its normal
level. Consequently it is of great importance to provide the utmost possible
facilities for the water to pass from the outside of the meter to the inlet end inside
the drum. This is effected by the inventor in three ways viz. 1st through the
orifice in the end disc. 2nd through the hollow core from the outlet end towards
the inlet end. 3rd by the passage of water over the core from the outlet to the
inlet end of the meter.
For renewing the water so as to make up for the loss by evaporation and other
causes and so to maintain a constant level of the water in the box the inventor
proposes to use a very small archimedean screw driven by the meter whenever it
is in action and lifting a very small quantity of water from a cistern at one end of
the box and discharging it into the water surrounding the meter. The surplus

page_text: water so discharged would be returned to the cistern by means of a pipe the top of
which is at the level which the water surrounding the meter is intended to
maintain. But the inventor may use for this purpose in connection with the
meter any one of the well known and recognized methods either of maintaining a
constant water level in the meter box or of allowing in other ways for the
alteration of the water level in consequence of evaporation &c. so as to secure a
correct register of the amount of gas passed through the meter. And the inventor
proposes also to use instead of water glycerine, or a mixture of glycerine and
water, or oil, or any other fluid or mixture of fluids which would be less liablo to
waste by evaporation or otherwise and would supersede the necessity of mechanical
renewal of the fluid.
The inventor claims for his Invention as above described the following advantages.
1. That it consists of but few separate parts is easily constructed, and strong.
2. That it is certain in its action and accurate in its measureinent.
3. That the water passages are large and open, and that the circulation of the
water during the revolution of the metor is simple and complete.
4. That by reason of the smooth spiral surfaces of the threads and other smooth
metallic surfaces the water friction is reduced to a small amount.
5. That in consequence of the last mentioned two advantages the meter revolves
more rapidly than the wet meters in ordinary use, and the quantity of gas that
can bo passed through a meter of given capacity in a given time is greater than
can be passed through an ordinary wet meter of the same capacity in the same
time.
6. That as the delivery of gas from the meter, proceeds by a rapid succession of
small quantities the pressure outside the ineter will be maintained more equably
than is the case with the ordinary wet meters where the rate of revolution is
slower and the individual discharges are larger.
The arrangement of meter may be modified for measuring water, oil, or other
fluids of considerable specific gravity by means of a fluid of smaller specific gravity.
For the sake of clearness in the following description it will be assumed that the
fluid to be measured is water and the lighter fluid air.
The construction of the meter is as already described in the first part of this
Specification. But in the present case it is to a great extent immaterial whether
the core is made solid or hollow, and by preference the core will be made solid, or
hollow and closed up entirely. And as in the case first described the drum may
have any number of threads but in general three or four threads will be sufficient
to ensure an equable flow of water from the meter.
The action of the meter is as follows:—
The meter is placed so that the axis of the drum is horizontal or nearly so.-
Water is poured into the box and into the drum till both the drum and the space
surrounding the drum are filled to a normal level not so high as the bottom of the
orifice in the end disc. The box is then strongly closed and made air-tight, and
the upper part of the box and meter above the water surface is charged with air
by means of a detached air-pump at the pressure of the water from which the
entry pipe is led. Communication is then effected with the water in the entry
pipe by means of a tap, and when water is drawn off from the box by means of
the outlet pipe the pressure of the water inside the meter acting on the inclined
spiral threads will cause it to revolve and the supply will be renewed through
the entry pipe. The spiral threads are made of such length that when the lower
uprising edge of the mouth of a spiral chamber has just risen above the water at
the inlet end of the meter the lower descending edge of the mouth of the same
spiral chamber at the outlet end of the meter has not sunk below the surface of
the water. Consequently as the drum revolves successive spiral chambers-full of
water are poured out at the outlet end into the space surrounding the drum and
hence by the outlet pipe to where it is being used. The total quantity of water
passed through the meter per revolution will be determined by experiment and
will continue constant so long as the water level remains constant. The number

page_text: of revolutions will be shewn by the counter and therefore the total quantity of
water passed in any given interval will be accurately ascertained by inspection
in the ordinary way. The constancy of the water level is ensured in the following
way. As the meter revolves a small air pump continually forces a small quantity
of air into the upper part of the box in order to renew and make good any waste
of the air caused by absorption or mechanical removal of the air by the water.
The surplus air so forced into the box is allowed to escape by means of a tap
which is opened by a float whenever the level of the water surface is depressed
below the normal level at which the counter correctly registers the volume of water
passed. When the float has regained its normal position it closes the tap and thus
the water surface is maintained at its normal level. The same arrangement is
provided for the restoration of the normal level of the water surface in the event
of a variation of pressure of the water in the entry pipe.
The inventor claims for his Invention as above described the following
advantages.
1. That it consists of but few separate parts, is easily constructed and strong.
2. That it is certain in its action and accurate in its measurement.
3. That the water passages are large and open.
4. That the water flows through the meter in a straight current without bends
or obstructious of any kind.
5. That by reason of the smooth spiral surfaces of the threads and other smooth
metallic surfaces the water friction is reduced to a small amount.
6. That in consequence of the above mentioned advantages the meter revolves
very readily and with very small loss of pressure.
7. That as the delivery of water from the meter proceeds by a rapid succession
of small quantities the pressure outside the meter will be maintained very equably
and with very slight oscillation.