Improvements in and relating to Water Meters.
Year: 1896

page_text: Date of Application, 13th Aug., 1896-Accepted, 19th Sept., 1896
COMPLETE SPECIFICATION.
Improvements in and relating to Water Meters.
I, FRIEDRICH LUX, of Ludwigshafen-on-the-Rhine, in the Kingdom of
Bavaria, and Empire of Germany, Manufacturer, do hereby declare the nature
of this invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement:-
My invention relates to water meters as hereinafter described.
The usual wing-wheel water meters, by reason of their construction, present this
fundamental objection that, so long as the water passing therethrough has not yet
attained a certain quantity per unit of time (say, litres per hour), these water
meters will at first fail to indicate anything at all, whereas, upon the quantity of
passing water having gradually risen to a certain value, they will indicate part
of this quantity; but they will not indicate the entire quantity of water until a
still further increase has taken place. This error increases in proportion with the
size of the water meters and, therefore, becomes excessively great at times in
the case of large size conduits.
With a view to removing this objection it has been proposed to provide in
combination with a large water meter a smaller one, arranged parallel to the
former, and to provide, either directly in front or in the rear of the large water
meter, a valve so adjusted as to open only when the difference in the pressures
acting on the front and rear sides thereof reaches a certain predetermined limit.
In an arrangement of this kind those quantities of water which correspond to a
relatively small discharge in a given unit of time will pass through the smaller
water meter, whereas those quantities which correspond to a relatively great
discharge will pass through both the small and the large meter, and the quantity
thus passing through the large meter will then be correctly registered by the
latter.
However, in the case of a medium discharge, when the valve is just barely
opened, the quantities of water passing through the large meter will again be only
partly measured, or not at all.
A perfectly correct operation, in a combination of the kind above referred to,
would be obtained only if the valve were made to open, not gradually, but
suddenly and at once to a sufficiently great width to make sure that the quantity
of water passing the same in a given unit of time is large enough to be correctly
measured by the large meter.
To obtain this result is the object of my present invention; and, with a view to
the attainment of this object, my invention consists in transforming the usual
combination valve-no matter whether the latter be a hydraulic valve or a spring-
valve into what may be termed a "differential " valve, that is to say, a valve the
equation of forces of which, when the valve is closed, will represent a higher value
for the difference in pressure directly in front and in the rear of the valve when
the said valve is open.
In the accompanying drawings:-
Figure 1 is a section of an hydraulic valve.
Figure 2 is a section of a spring actuated valve and
Figure 3 is a section of a similar valve operated by a weight.
I provide ou the outside of, and at a suitable distance from, the valve seat B of
any of the usual forms of valve a guideway such as D, loosely surrounding the
periphery of the valve and having a larger sectional area than the opening covered

page_text: by the valve when on its seat, so that the valve A, in being lifted from its seat,
will with its periphery freely slide for a short distance within the said guideway
and will, immediately upon having been lifted from its seat, have its entire area
acted upon by the difference in pressure, whereas, during the time when the valve
rested on its seat, it presented only that portion of its area which was exposed by
the valve opening.
In other words: when the diameter of the valve A, as shown in the drawings,
is increased to a certain extent, that is to say, when its surface is made larger by
the additional annular portion BC which extends beyond the valve seat B, and
when the valve is provided with a comparatively loosely fitting cylindrical or other
guideway D extending to a short distance of its stroke, then the difference in
pressure, established upon water being discharged from the conduit, will, when the
valve is closed, act only upon the smaller area B--B (since the pressure prevailing
on the rear of the valve, and acting on both sides of the annular surface, is
equalized), whereas, immediately upon the valve being opened, it will act upon the
total superficial area C-C of the said valve.
Therefore, if the quantity of water discharge in a given unit of time be so large
as to cause the corresponding difference in pressure to exceed the resistance of the
valve, when the latter is closed, then the latter will be opened, and from this very
moment the difference in pressure will act upon the larger superficial area C-C,
and, hence, with increased force, thus causing the valve to be pushed along until
the forces acting thereon will have regained a state of equilibrium. And this will
only occur when the valve, in leaving its guideway D, will have become opened to
such an extent that the product of the (by this means) increased sectional area for
the passage of the water and of the reduced difference in pressure (equal to the
quantity of water passing in the unit of time) will again have become equal to the
product of the original superficial area and the original difference in pressure.
Supposing that a designate the number of litres of water passing through
the small water meter at the original difference in pressure, then the quantity of
water which will pass through the small meter, upou the valve having been opened
and the difference in pressure reduced thereby, will be 6 litres, whereas the quantity
passing through the large meter will be a-b litres. Thus, by correspondingly
adapting the relative proportion of the two valve surfaces, I am enabled to so
regulate the value a-b that it will be correctly registered by the large water
meter.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. In a water-meter combination as described, a valve having a valve seat, and
a guideway arranged outside of the valve opening at a distance therefrom and
loosely surrounding the periphery of the said valve, so that the latter will, in
moving away from its seat, freely slide within the said guideway during a portion
of its movement.
2. The herein described improvements connected with water meters constructed
arranged and operated substantially as hereinbefore described and shown in the
drawings.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.