A New Process of and Means for Cleaning Filter-material.
Year: 1898

page_text: Date of Application, 10th Oct., 1898
Complete Specification Left, 4th Apr., 1899-Accepted, 1st July, 1899
PROVISIONAL SPECIFICATION.
A New Process of and Means for Cleaning Filter-material.
I, ALFRED DERVAUX, of 73, Boulevard du Nord, Brussels, in the Kingdom of
Belgium, Engineer, do hereby declare the nature of this invention to be as
follows:-
In gravel or sand-filters the very minute distribution of the impurities present
in unfiltered water, as soon as the filter is set in action after a thorough cleaning,
causes, at first, not quite clear water to pass out of the apparatus, because not all
the impurities are kept back by the thoroughly cleansed gravel. etc. Not until the
unfiltered water has passed through the filtering substance for a certain time does
the filtered water come out perfectly clear. The cause of this will be seen in what
follows; It is true the gravel, and so forth can keep back a certain amount of
the impure substances but is not in itself the actual filter-material; in fact the
real filtering is caused by the impurities still remaining behind in the filtering-
substance that is to say by the silt itself. Indeed in a certain sense the filtering-
substance only serves as a repository for the actual filtering components that is
for the filtering silt.
To accomplish the perfect filtration of unfiltered water a suitable quantity of
that particular kind of water is necessary in which there is silt, in which filter-
material is contained:-If this quantity of silt is not there the water passing
through the filter-material will not be thoroughly cleansed because a certain
amount of insoluble, suspended components can pass through the compartments
of the filter, but if there is a sufficient quantity of silt in or upon the filter-material
in reserve, to prevent the passing of every single impurity the water will pass
out from the filter-apparatus absolutely clear.
At
The more unfiltered water flows through the filtration-stuff the more silt collects
in or on the filter, and so much the more resistance to the passing through of the
water. It will at last reach a point at which the silt collected in or on the filter-
stuff offers a resistance which balances the column of water to be filtered.
this precise moment the cleansing of the filterstuff must take place so that the
further filtration may be effective. After what has been previously said it is
therefore manifest that the object must be during the cleansing of the filterstuff
not to get rid of the entire mass of silt but to leave behind a certain fixed quantity
of it which when the fresh stream of unfiltered water flows in keeps back the
collected impurities of the latter but on the other hand is sufficiently small in
quantity to offer the very smallest resistance to the inrush of the water to be
filtered. In this way without any loss of labour at all pure water is obtained.-
Now the above-mentioned process gains for its object an effective automatic clean-
ing out of the filter-stuff and also a renewed power of working the apparatus, and
at the same time by leaving behind a certain amount of the silt in the filter to
effect a thorough cleansing of the water immediately upon setting the apparatus
in action.
In order that my invention may be fully understood I will proceed to describe
the drawing annexed in which a longitudinal section of the apparatus to be
employed for carrying the invention into effect is represented.
The water to be filtered flows through a pipe A into the cylinder B which carries
it into the chamber C, above the filterbed F. The latter rests upon the perforated

page_text: bottom P.
The water rushes through the filterstuff F from top to bottom passes
on into the chamber V and reaches from here the central pipe K out of which
it rises into the reservoir R. It leaves this reservoir through the cup D and the
waste pipe E so that the level N is uniformly maintained. The filterstuff F offers
a continually increasing resistance to the iurush of water in proportion to the mass
of silt left behind so that in the cylinder B the level of the unfiltered water must
continually rise while that of the filtered water in the reservoir R remains the
same. Further in the reservoir R a receiver L is arranged which above is closed
and stands in close connection with the filter C. In this receiver L there is the
pipe S which discharges underneath the filter apparatus into the silt-room Y. The
connection of the receiver L and the pipe S, which discharges underneath the
filter, together produce a siphon, for there will be a sucking action set up as soon
as, within the receiver L, the rising water reaches the upper mouth J of the pipe S.
Now exactly as the unfiltered water in the cylinder B rises proportionally to the
silt retained in the filter, so the level in the unfiltered water in the receiver L
rises until it reaches the opening J of the pipe S. At this moment the siphon LS
commences working and sucks the filtered water out of the cistern R through
the filterstuff from bottom to top entirely and with such power moreover that
in a few seconds almost the entire mass of silt is removed from the filter and
together with the water is carried off into the silt-room Y. At the head of the
receiver L a pipe Z of small diameter is placed which reaches down into the water
of the reservoir R to a certain fixed level M. As soon as the lower opening of the
pipe is free in consequence of the sucking out of the water from the reservoir R
the water in the room 1 sucking below the level M-the siphon S begins to cease
acting because atmospheric air enters through the pipe Z. The unfiltered water
which had flowed through the cylinder B into the filter chamber C but at the same
time as the filtered water during the few moments of the back-suction of the pure
water was also sucked up by the siphon gradually flows again from top to bottom
through the filterstuff F so that purified once again it rises through the pipe K
into the reservoir R so as to flow off by D E as soon as the level N is again reached.
For the reason that the violent suction only lasts as long as the water in the reser-
voir does not sink below the level M a certain quantity of silt remains behind in
the filter which works in such a way that immediately after the renewed backflow
of the unfiltered water through the filterstuff perfectly clear water runs out of the
apparatus.
The mass of the silt retained arranges itself according to the depth of the open-
ing of the pipe 7-and can be suitably adapted to any apparatus in which always
the same sort of water is used. As the siphon gradually ceases to act and the new
filtration also gradually begins so is the production of perfectly clear water from
the beginning still further secured. It is also a great advantage that the cleaning
out as well as the renewed filtration is effected quite automatically; so that all
manual labour and supervision is unnecessary and the cleansing proceeds always at
the proper time.
D
1
10
,
1000
I, ALFRED DERVAUX, of 73, Boulevard du Nord, Brussels, in the Kingdom of 5
Belgium, Engineer, do hereby declare the nature of this my invention, and in what

page_text: manner the same is to be performed, to be particularly described and ascertained
in and by the following statement; -
In gravel or sand-filters the very minute distribution of the impurities present
in unfiltered water, as soon as the filter is set in action after a thorough cleansing,
causes, at first, not quite clear water to pass out of the apparatus, because not all
the impurities are kept back by the thoroughly cleansed gravel etc. Not until the
unfiltered water has passed through the filtering substance for a certain time does
the filtered water come out perfectly clear. The cause of this will be seen in what
follows: It is true the gravel, and so forth can keep back a certain amount of
the impure substances but is not in itself the actual filter-material; in fact the
real filtering is caused by the impurities still remaining behind in the filtering-
substance, that is to say by the silt itself. Indeed in a certain sense the filtering-
substance only serves as a repository for the actual filtering components that is
for the filtering silt.
To accomplish the perfect filtration of unfiltered water a suitable quantity of
that particular kind of water is necessary in which there is silt, in which filter-
material is contained-If this quantity of silt is not there the water passing
through the filter-material will not be thoroughly cleansed because a certain
amount of insoluble, suspended components can pass through the compartments
of the filter, but if there is a sufficient quantity of silt in or upon the filter-material
in reserve, to prevent the passing of every single impurity the water will pass
out from the filter-apparatus absolutely clear.
The more unfiltered water flows through the filtration-stuff the more silt collects
in or on the filter, and so much the more resistance to the passing through the
water. It will at last reach a point at which the silt collected in or on the filter-
stuff offers a resistance which balances the column of water to be filtered. At
this precise moment the cleansing of the filter-stuff must take place so that the
further filtration may be effective. After what has been previously said it is
therefore manifest that the object must be during the cleansing of the filterstuff
not to get rid of the entire mass of silt but to leave behind a certain fixed quantity
of it which when the fresh stream of unfiltered water flows in keeps back the
collected impurities of the latter but on the other hand is sufficiently small in
quantity to offer the very smallest resistance to the inrush of the water to be
filtered. In this way without any loss of labour at all pure water is obtained.-
Now the above-mentioned process gains for its object an effective automatic clean-
sing out of the filter-stuff on the principles herein specified-that is--without
any manual labour and without any supervision and always at the right time
producing a cleansing out of the filter-stuff and also a renewed power of working
the apparatus and at the same time by leaving behind a certain amount of the silt
in the filter to effect a thorough cleansing of the water immediately upon setting
the apparatus in action.
In order that my invention may be fully understood I will proceed to describe
the drawing which accompanied my Provisional Specification and in which a
longitudinal section of the apparatus to be employed for carrying the invention
into effect is represented.
The water to be filtered flows through a pipe A into the cylinder B which carries
it into the chamber C, above the filterbed F. The latter rests upon the perforated
bottom P. The water rushes through the filter stuff I from top to bottom passes
on into the chamber and reaches from here the central pipe K out of which
it rises into the reservoir R. It leaves this reservoir through the cup D and the
waste pipe E so that the level N is uniformly maintained. The filterstuff F offers
a continually increasing resistance to the inrush of water in proportion to the mass
of silt left behind so that in the cylinder B the level of the unfiltered water must
continually rise while that of the filtered water in the reservoir R remains the
same. Further in the reservoir R a receiver L is arranged which above is closed
and stands in close connection with the filter C. In this receiver L there is the

page_text: pipe S which discharges underneath the filterapparatus into the silt-room V. The
connection of the receiver L and the pipe S, which discharges underneath the
filter, together produce a siphon, for there will be a sucking action set up as soon
as, within the receiver L, the rising water reaches the upper mouth J of the pipe S.
Now exactly as the unfiltered water in the cylinder B rises proportionately to the
silt retained in the filter so the level in the unfiltered water in the receiver L
rises until it reaches the opening J of the pipe S. At this moment the siphon LS
commences working and sucks the filtered water out of the cistern R through
the filterstuff F' from bottom to top entirely and with such power moreover that
in a few seconds almost the entire mass of silt is removed from the filter and
together with the water is carried off into the silt-room Y. At the head of the
receiver L a pipe Z of small diameter is placed which reaches down into the water
of the receiver R to a certain fixed level M. As soon as the lower opening of the
pipe is free in consequence of the sucking out of the water from the reservoir R
the water in the roomi R sucking below the level M-the siphon S begins to cease
acting because atmospheric air enters through the pipe Z. The unfiltered water
which had flowed through the cylinder B into the filterchamber C but at the same
time as the filtered water during the few moments of the back-suction of the pure
water was also sucked up by the siphon gradually flows again from top to bottom
through the filterstuff so that purified once again it rises through the pipe K
into the reservoir R so as to flow off by D E as soon as the level N is again reached.
For the reason that the violent suction only lasts as long as the water in the reser-
voir does not sink below the level M a certain quantity of silt remains behind in
the filter which works in such a way that immediately after the renewed backflow
of the unfiltered water through the filterstuff perfectly clear water runs out of the
apparatus.
The mass of the silt retained arranges itself according to the depth of the open-
ing of the pipe Zand can be suitably adapted to any apparatus in which always
the same sort of water is used. As the siphon gradually ceases to act and the new
filtration also gradually begins so is the production of perfectly clear water from
the beginning still further secured. It is also a great advantage that the cleaning
out as well as the renewed filtration is effected quite automatically: so that all
manual labour and supervision is unnecessary and the cleansing proceeds always at
the proper time.
Having now particularly described and ascertained the nature of this invention,
and in what manner the same is to be performed, I declare that what I claim is:--
The process of automatically cleansing filter-material, consisting in forcing a
column of unfiltered water to rise during the period of filtering in consequence of
the increasing resistance of the impurities retained in the filter to such a degree
as to introduce the action of a siphon forcing cleansing-water through the filter-
material, and stopping the action of the said siphon before the filter-material be
freed from all impurities, substantially as set forth.
Motod his 4th day of Anvil 1800
GEO. THOS. HYDE,
1, Broad Street Buildings, Liverpool Street, London, E.C.
Agent for Applicant.