Improvements in Filters.
Year: 1892

page_text: Date of Application, 24th Dec.,. 1892
Complete Specification Left, 23rd Sept., 1893-Accepted, 9th Dec., 1893
PROVISIONAL SPECIFICATION.
Improvements in Filters.
We, EDMOND DELHOTEL and EDOUARD MORIDE both of 30 Rue de Lille,
Paris, France, Gentlemen, do hereby declare the nature of this invention to be
as follows:-
1
This invention relates to improvements in filters and is designed to obviate the
disadvantages that have hitherto obtained with filters containing sand or equivalent
finely divided material.
Sand filters give when new considerable output in proportion to the extent of
their filtering surfaces. When however water highly charged with impurities is
caused to pass into a sand filter, it is found that although the output of the filter is
high at first, it rapidly diminishes until in a few hours it is only a very small
fraction of the initial output.
This decrease in the capacity of the filter is not due to complete fouling or
choking of the sand but merely to the deposition in a layer on the surface of the
impurities of the water.
After the lapse of a certain period this layer begins to play the part of a filter.
The minute particles which form the same, oppose the passage of substances, even
the very finest carried by the water. The sand then serves merely as a support.
Under these circumstances, it will be readily understood that the sand filter loses a
great part of its advantages.
In order to remedy these drawbacks according to this invention the water to be
filtered is caused to flow on to the surface of the sand in such a manner that it
assumes a gyratory movement which it imparts to the body of liquid covering the
sand. Under these conditions the sand is constantly rubbed by the streams of
liquid in motion, whereby those particles which are less dense than the sand and
which are being constantly removed from the water, are kept in motion.
The mud is thus held in suspension in the water above the sand the surface of
which remains comparatively clean, and there is no longer any tendency to the
formation of a superficial deposit of bat slight permeability.
If the filter is arranged in such a manner as to allow of the water forming a
whirl or eddy around a central or dead point therein, in a central funnel for
instance, the impurities will tend to collect and become deposited at this point and.
can be discharged through a discharge-cock.
The water after having passed through the sand, will pass through a layer or
sheet of metallic cloth or other such material which keeps back the sand. The
filtered water then enters the distributing pipe or conduit.
One form of apparatus according to this invention consists of a metal reservoir
of cylindrical or other shape in which fine sand is placed. At the centre of the
reservoir is a vertical tube having at its upper part a funnel and at its lower part a.
cock. A pipe connected to an external source of supply terminates in a crown or
ring provided with distributing devices which may be suitably bent or curved.
This pipe serves to bring the water to the filter.
A layer or sheet of metallic cloth is placed at the lower part of the layer of
Band between cross pieces.
The filtered water as stated passes out of the filter by a tube and flows away
through the delivery conduit.
The supply and delivery conduits are connected together for washing the filter
as will be explained later on.
Two-way cocks are provided in these conduits.

page_text: In consequence of the arrangement of the distributing devices the water to be
filtered, assumes as above mentioned, a gyratory movement which draws the upper-
most layer of sand along with it. The water, after traversing the filter, falls into
the outlet tube, and cocks are arranged so as to enable the filtered water to be
discharged by the delivery conduit.
To clean the surface of the filter, means such as a discharge cock are provided
for relieving the upper part of the filter of pressure. Under the influence of the
counter-pressure of the filtered water and of the reduction of pressure of the
inflowing water, a slight ascending movement of the mass takes place. This
causes the upper part of the sand to be agitated and washed by the current of
water the velocity of which has increased owing to the aforesaid difference in the
pressures. Under the influence of this current, the impurities are caused to enter
the funnel whilst the sand, being more dense, is set in motion but cannot rise high
enough to be carried away if the apparatus is suitably arranged.
1111
This cleansing of the surface can be very quickly performed and requires merely
the simple opening of a cock which can be effected either by hand, or by any other
suitable means, it may be automatically.
This cleansing restores the filter almost to its original efficiency.
Our apparatus is also arranged in such a manner as to be capable of being
easily cleaned by a reverse current of water.
For this purpose the cocks are so arranged that the water, can be caused to enter
the filter by the lower part but so that there shall not be any communication
between the clean water conduit and the unfiltered water conduit.
The water entering below the sand carries the same upwards in the filter.
Having reached a certain height, the velocity of the liquid is no longer sufficient to
enable the sand to remain in suspension and it falls down again. The grains of
sand in thus rising and falling, rub against one another and become cleaned in an
efficient manner.
The impurities being less dense are carried off by the current
and pass away by means of the funnel.
The normal working is in this case resumed by turning the cocks so as to cause
the unfiltered water to enter the upper part of the filter. A two-way cock is also
provided to allow of blowing through for a short time before sending the water
into the filtered water conduit.
Instead of washing-out with unfiltered water, distilled or filtered water may be
employed.
The action of our filter can be rendered more effective by placing coagulating
reagents such as aluminous or ferric salts in the supply pipe.
By reason of the facility in cleaning, such a filter may be arranged in connection
with apparatus for distributing and mixing purifying compounds, when it will arrest
the chemical precipitates as well as the substances originally in suspension in the
water.
In order to obtain complete purification the surface of the sand may be covered
with a fine powder or purifying substance such as for instance, oxide of iron, or
vegetable or animal charcoal.
According to another arrangement a reservoir containing sand is placed in a
larger reservoir. The central tube and funnel are dispensed with, and the
impurities escape at the sides through the space between the reservoirs.
As will be obvious filters constructed as described may be variously modified
without departing from the nature of the invention.
Dated this 24th day of December 1892.

page_text: COMPLETE SPECIFICATION.
Improvements in Filters.
We, EDMOND DELHOTEL and EDOUARD MORIDE, both of 30 Rue de Lille,
Paris, France, Gentlemen, 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 :-
This invention relates to improvements in filters and is designed to obviate the
disadvantages that have hitherto obtained with filters containing sand or equivalent
finely divided material.
Sand filters give, when new, a considerable output in proportion to the extent of
their filtering surfaces. When, however, water highly charged with impurities is
caused to pass into such a filter, it is found that, although the output of the filter
is high at first, it rapidly diminishes until in a few hours it is only a very small
fraction of the initial output.
This decrease in the capacity of the filter is not due to complete fouling or
choking of the sand but merely to the deposition in a layer on the surface of the
sand, of the impurities of the water.
After a certain time this layer begins to play the part of a filter. The minute
particles which form the same, oppose the passage of substances, even the very
finest, carried by the water. The sand then serves merely as a support for the said
layer. Under these circumstances, it will be readily understood that the sand
filter loses a great part of its advantages.
In order to remedy these drawbacks, according to this invention, the water to be
filtered is caused to flow on to the surface of the sand in such a manner that it
assumes a gyratory movement which it imparts to the body of liquid covering the
sand. Under these conditions the sand is constantly rubbed by the streams of
liquid in motion, whereby those particles which are less dense than the sand and
which are being constantly removed from the water, are kept in motion.
The mud is thus held in suspension in the water above the sand the surface of
which remains comparatively clean, and there is no longer any tendency to the
formation of a superficial deposit of but slight permeability.
If the filter is arranged in such a manner as to allow of the water forming a
whirl or eddy around a central or dead point therein, in a central funnel for
instance, the impurities will tend to collect and become deposited at this point and
can be discharged through a discharge-cock.
The water after passing through the sand, passes through a layer or sheet of
suitable material such as metallic cloth which keeps back the sand. The filtered
water then enters the distributing pipe or conduit.
In the accompanying drawings,
Fig. 1 is a vertical central section partly in elevation; and
Fig. 2 a sectional plan of a filter constructed according to this invention.
R is a metal reservoir that may be of cylindrical shape as shown and which
contains fine sand up to the level a b. At the centre of the reservoir is a vertical
tube T having at its upper part a funnel C and at its lower part a cock D. A is
a pipe connected to an external supply pipe E, and terminating within the reservoir
in a crown or ring provided with distributing devices in the form of pipes B which
are suitably bent or curved as shewn in Fig. 2. The pipe A supplies the water to
be filtered.
F is a layer or sheet of metallic cloth placed at the lower part of the mass of
and and held between suitable cross pieces as shown.
The filtered water passes out of the filter by a tube I and flows away through
he delivery conduit J.
The supply and delivery conduits E I and J are connected together and provided

page_text: with two-way cocks G, H and K for enabling the filter to be washed as will be
hereinafter explained.
In consequence of the arrangement of the distributing devices or pipes B the
water to be filtered assumes, as above mentioned, a gyratory movement which
draws the uppermost layer of sand along with it. The water, after traversing the
filter, passes into the outlet tube I and the cocks G H and K are turned so as to
enable the filtered water to be discharged by the delivery conduit J.
To clean the surface of the filter the discharge cock D is opened and the upper
part of the filter thus relieved of pressure. Under the influence of the counter-
pressure of the filtered water and of the reduction of pressure of the inflowing
water, a slight ascending movement of the mass of sand takes place. This causes
the upper part of the sand to be agitated and washed by the current of water the
velocity of which has increased owing to the aforesaid difference in the pressures.
Under the influence of this current a gyratory or whirling motion is imparted to
the impurities which are thereby caused to enter the funnel C and flow off through
the cock D whilst the sand, although set in motion, is more dense and cannot rise
high enough to be carried away if the top of the funnel C be arranged at a suitable
height as shown.
This cleansing of the surface of the mass of sand can be very quickly performed
and requires merely the simple opening of a cock which can be effected either by
hand, or by any other suitable means, it may be automatically.
This cleansing restores the filter almost to its original efficiency.
As will be seen our apparatus is so constructed and arranged as to be capable of
being easily cleaned by a current of water caused to flow in the reverse direction
through the sand, so that should the mass of sand become charged with impurities
it can be readily cleaned.
For this purpose the cocks G H and K are so operated that the water instead
of passing from pipe E into pipe A and thence through the mass of sand to
pipe I is caused to enter the filter by the said pipe I the, cock K being closed so
that there shall not be any communication between the clean water conduit J
and the unfiltered water conduit E.
The water entering freely below the sand, carries the same upwards in the filter.
Having reached a certain height the velocity of the water is no longer sufficient to
enable the sand to remain in suspension and it falls down again. The grains of sand
in thus rising and falling, rub against one another and become cleaned in an efficient
manner. The impurities being less dense, are carried upward by the current and
then pass away in a downward direction through the funnel C and the cock D
which is then open.
The normal working is resumed by closing the cock D and turning the cock G
so as to cause unfiltered water to again enter the upper part of the filter. The two-
way cock H also serves to allow of blowing through for a short time before sending
the water into the filtered water conduit.
Instead of washing-out with unfiltered water, distilled or filtered water may be
employed for this purpose, in which latter case the cock G is closed and the cocks K
and H turned so as to place the conduit J in communication with the bottom of the
filter.
The action of the filter can be rendered more effective by placing coagulating
reagents such as aluminous or ferric hydrates in the supply pipe E.
By reason of the facility in cleaning, such a filter may be arranged in connection
with apparatus for distributing and mixing purifying compounds, when it will arrest
the chemical precipitates as well as the substances originally in suspension in the
water.
In order to obtain complete purification, the surface of the sand may be covered
with a fine powder or purifying substance, such for instance as oxide of iron, or
vegetable or animal charcoal.
Fig. 3 is a vertical section to a reduced scale showing a modified arrangement in
which the reservoir » containing the sand s is placed in a larger reservoir ¹. The

page_text: central tube T and funnel Care here dispensed with, and the impurities escape at.
the sides through the space t¹ between the two reservoirs.
As will be obvious filters constructed as described may be variously modified
without departing from the nature of the invention.
Having now particularly described and ascertained the nature of the said inven--
tion and in what manner the same is to be performed we declare that what we
claim is :-
1. A sand filter in which the water is introduced by a pipe or conduit connected
to or ending in bent or curved distributing devices B, so constructed and arranged
as to impart to the water or other liquid introduced into the top of the filter a
gyratory movement which carries with it the upper layer of the sand and prevents.
the same from becoming fouled or charged with impurities.
2. A sand filter of the kind referred to in the preceding claim provided with a
central vertical tube having at its upper end a funnel and at its lower end a
discharge cock; and with pipes or conduits with cocks, the arrangement being such
that a reverse current of filtered, or unfiltered water, can be caused to enter the
lower part of the filter and flow upward through the sand therein for the purpose of
cleaning the same substantially as herein described.
3. A filter of the kind referred to in Claim 1, composed of two vessels placed one
within the other in such a manner as to leave between them an overflow space
through which impurities can escape.
4. The improved filter constructed arranged and operating as hereinbefore
described with reference respectively to and shown in Figs. 1 and 2, and in Fig. 3 of
the drawings annexed.
Dated this 23rd day of September 1893.
E. DELHOTEL,
E. MORIDE,
By L. W., per W. C.