Improvements in Filters and their Installation.
Year: 1896

page_text: Improvements in Filters and their Installation.
I, WOLF DEFRIES, of 4 Danes Inn, Strand, London, Engineer, do hereby declare
the nature of this invention to be as follows,
My invention relates to those filters in which the filtering medium is such that
within wide limits the certainty of the filtration is independent of the pressure
under which the liquid to be filtered is delivered. Its object is. to provide simple
means of constructing and working such filters.
In applying my invention to those filters which are worked by the production
of a partial vacuum in the filtered water-chamber I so select the dimensions of the
pump or other apparatus determining the vacuum and regulate its speed that it
is only capable of pumping the minimum quantity of water which it is
intended to take from the filter to which it is attached. In this way, as
compared with the ordinary method in which it is endeavoured to obtain
initially a higher output, the deposit first attaching to the filtering medium
is attached with the least pressure and the whole deposit is usually therefore, the
more readily detached when it is desired to remove it, while the filter will continue
to give this normal output for a longer time without removal of the deposit. As
the pores of the filtering medium become obstructed by deposit, the vacuum produced
by the pump in drawing its normal quantity of wator for the filter is increased:
I therefore provide a vacuum gauge communicating with the filtered water
chamber, and its reading serves as an indication of the extent of deposit which has
occurred and ultimately of the epoch at which it should be removed.
I may adopt any ordinary method of removing the deposit, and I may before
starting filtration float a coating of Kieselguhr or other light material on to the
tubes. If I do this, I prefer to construct my filter in a trough. shaped form, and
in charging with the Kieselguhr determine a flow of water from end to end of it,
pumping the water if necessary, backwards and forwards or through and through
until a sufficient deposit has been uniformly distributed over the filtering medium.
I may interpose inclined baffle plates at convenient distances along the trough, so
thst the direction of motion of the powder, which tends to settle by gravitation,
may be altered through the alteration given by the baffle plates to the flow of the
water which carries it. For some waters I dispense with the use of Kieselguhr or
equivalent material, and, having emptied the filter of its water, steep it in a suit-
able solution, such as undiluted or diluted hydrochloric acid is for such waters as
I have examined. By a suitable solution I mean one which sufficiently dissolves
out the substances which attach the deposit to the tubes to enable it to be readily
detached from them, and at the same time sterilises the tulies. I may introduce my
solution by means of a spraying apparatus, consisting for instance of sparge pipes
perforated at various angles to cover the whole of the filtering surface or surfaces,
and connected by mains suitably braced together for supplying the solution. These
mains with their braced frame may be capable of a traverse longitudinally or
transversely so as to both vary the position of the jets in relation to the

page_text: various parts of the filtering medium and to enable a larger surface to be covered
by a given number of sparge pipes. I may prolong the use of this apparatus with
the solution so as to detach the deposit during the application of the acid, in such
case taking care that when it is desired to remove the deposit the solution is
allowed to run off, so that the power of the jets may be reserved for the removal
of the deposit; or I may use this apparatus with ordinary or with filtered water in
a similar way.
In certain cases I may desire to use backward filtration and where the filtering
medium consists of tubes closed at their upper end and having their open lower end
projecting into the filtered water chamber, the ordinary method of backward
filtration would leave the tubes to a large extent full of air and prevent the liquid
from coming into contact with the filtering tubes, or at least with a sufficient
portion of them. To meet this difficulty in the case of those tubes,, such as Pasteur
(Chamberland) tubes, in which the tube when steeped in water is capable of prevent-
ing the entrance of air, even with a perfect vacuum in its interior, I empty the
unfiltered water cell and exhaust the filtered water chamber to the highest degree,
and so arrange the valve or valves controlling the entrance of the liquid to be
filtered backwards that it is admitted to the filtered water chamber while the latter
is still exhausted. Before exhaustion I may fill the filtered water chamber with
liquid of the same kind as that intended to be used for backward filtration so that.
the exhaustion prior to the admission of the actual liquid may be as nearly as
possible confined to the air within the filter tubes and the total quantity of air
which on admission of that liquid remains within them be as small as possible.
The liquid to be filtered backwards may be filtered under any convenient pressure;
and I find considerable advantage in either allowing the tubes to steep in the
solvent before mentioned before applying the backward filtration or in some cases
in using the solvent itself for the purpose of backward filtration.
These methods and constructions are applicable to a combination of several
filters to make an installation. In such application each cell liable to be separately
cleaned will be furnished with an independent exhaust pump and gauge. Where
it is desired to employ a steam pump of which the regulator does not sufficiently
control the speed under varying load, the steam supply may be controlled by a valve
operated through suitable mechanism by the difference between the pressures
within and without the filtered water chamber.
In applying my invention to a pressure filter in which the pressure is
determined by a pump or equivalent mechanism I proceed in all respects as with
an exhaust filter such as I have described substituting only a pressure gauge for
a vacuum gauge on the pump, which in this instance deals with the unfiltered
instead of the filtered water. The maximum pressure is determined by a relief
valve in the ordinary way. Where the pressure is determined by a gravitation
head the inlet is controlled by a valve operated by a regulator placed on the
filtered water outlet, and the maximum pressure is fixed by a reducing valve, a
pressure gauge being inserted between the valve controlled by the regulator and
the inlet.
The materials to be employed in construction will be those ordinarily used for
liquids similar to those in question or any improvements upon them.
Instead of one liquid for cleaning, sterilisation, or backward filtration as above
described, I may use two or more consecutively, in which case if desired, one may
clean and one sterilise, or each in some measure discharge both functions, or the
combination do so by chemical reaction within the filters.
Dated this thirty-first day of December, 1896.

page_text: Improvements in Filters and their installation.
I, WOLF DEFRIES, of The Lawn, Thames Ditton, in the County of Surrey, (late
of 4 Danes Inn, Strand, London,) Engineer, 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 those filters in which the filtering medium is such that
within wide limits the certainty of the filtration is independent of the pressure
under which the liquid to be filtered is delivered. Its object is to provide simple
incans of constructing and working such filters.
In applying any invention to those filters which are worked by the production
of a partial vacuum in the filtered water-chamber, as for instance in the case of
a river supply, I so select the dimensions of the pump or other apparatus deter-
mining the vacuum and regulate its speed that it is only capable of pumping the
actual quantity of water which it is intended to take from the filter to which it is
attached. In this way as compared with the ordinary method in which it is
endeavoured to obtain initally a higher output, the deposit first attaching to
the filtering medium is attached with the least pressure and the whole deposit
is usually therefore, the more readily detached when it is desired to remove it,
while the filter will continue.to give this normal output for a longer time without
removal of the deposit.
As the pores of the filtering medium become obstructed by deposit, the vacuum
produced by the pump in drawing its normal quantity of water for the filter is
increased. I therefore provide a vacuum gauge communicating with the filtered
water chamber, and its reading serves as an indication of the extent of deposit
which has occurred and ultimately of the epoch at which it should be removed. It
will be observed that this reading denotes the effective pressure on the unfiltered
side necessary to produce the desired quantity of water.
I may adopt any ordinary method of removing the deposit, and I may before
starting filtration float a coating of Kieselguhr or other light material on to the
filtering tubes. If I do this I prefer to construct my filter in a trougn shaped form,
and in charging with tlic Kieselguhr determine a flow of water from end to end of
it, pumping the water, if necessary backwards and forwards or through and through
until a sufficient deposit has been uniformly distributed over the filtering medium.
I may interpose inclined baffle plates at couvenient distances along the trough so
that the direction of the motion of the powder which tends to settle by gravitation,
may be altered through the alteration given by the baffle plates to the flow of water
which carries it so as to distribute the powder over the filtering medium with
approximate uniformity. For some waters I may dispense with the use of Kiesel-
guhr or equivalent material, and, having emptied the filter of its water, steep it in
suitable solution, such as undiluted or diluted hydrochloric acid is for such wateis
as 1 have examined. By a suitable solution I mean one which sufficiently dissolves
out the probably colloid substances which are deposited in the tubes or which
attach the deposit to the tubes so as to enable the deposit to be readily detached
from them, and at the same time sterilises the tubes. I may introduce my solution
by means of a spraying apparatus, consisting for instance of sparge pipes per-
forated at various angles to cover the whole of the filtering surface or surfaces, and
connected by mains suitably braced together for supplying the solution. These
mains with their braced frame may be capable of a traverse longitudinally or
transversely so as to both vary the position of the jets in relation to the various
parts of the filtering medium and to enable a larger surface to be covered by a
given number of sparge pipes. I may prolong the use of this apparatus with the

page_text: solution so as to detach the deposit during the application of the acid, in such case
taking care that when it is desired to remove the deposit the solution is allowed to
run off, so that the power of the jets may be reserved for the removal of the
deposit or preferably after steeping the tubes for a sufficient time in the solvent,
1 may use this apparatus with ordinary or filtered water in a similar way.
In certain cases I may desire to use backward filtration. Where the filtering
medium consists of tubes closed at their upper end, and having their open lower end
projecting into the filtered water chamber, the ordinary method of backward
filtration would leave the tubes to a large extent full of air and prevent the liquid
from coming into contact with the filtering tubes, or at least with a sufficient
portion of them. To meet this difficulty in the case of those tubes,, auch as Pasteur
(Chamberland) tubes, in which the tube when steeped in water is capable of prevent-
ing the entrance of air, even with a perfect vacuum in its interior, I empty the
unfiltered water celi and oxhaust the filtered water chamber to the highest degree,
and so arrange the valve or valves controlling the entrance of the liquid to be
filtered backwards that it is admitted to the filtered water chamber while the latter
is still exhausted. Before exhaustion. I may fill the filtered water chamber with
liquid of the same kind as that intended to be used for backward filtration so that
the exhaustion prior to the admission of the actual liquid may be as nearly as
possible confined to the air within the filter tubes and the total quantity of air
which on admission of that liquid remains within them, be as small as possible.
The liquid to be filtered backwards may be filtered under any convenient pressure;-
and I find considerable advantage in either allowing the tubes to sleep in the
solvent before mentioned before applying the backward filtration or in some cases
in using the solvent itself for the purpose of backward filtration.
These methods and constructions are applicable to a combination of several
filters to make an installation. In such application each cell liable to be separately
cleaned will be furnished with an independent exhaust pump and gauge the speed
and output of each pump being thus kept constant and the vacuumi varying as
described.
In applying my invention to a pressure filter in which the pressure is
determined by a force pump or equivalent mechanism I proceed in all respects as
with an exhaust filter such as I have described, substituting only a pressure gauge
for a vacuum gauge on the pump, which in this instance deals with the unfiltered.
instead of the filtered water. The maximum pressure is determined by a reducing
or relief valve in the ordinary way. Where the pressure is determined by a
gravitation head I prefer to fix the inlet aperture by means of a cock or otherwise
of such dimensions as will in the least obstructed condition of the tubes permit
the passage of the desired quantity of water. As the tubes become obstructed the
pressure will rise on both sides of this inlet, and a pressure gauge attached to the
inlet main will give an indication as to the epochs of clearing similar to that
obtained in the vacuum construction, and like it varying with the effective
pressure on the unfiltered water necessary to produce the desired output.
The materials to be employed in construction will be those ordinarily used for
liquids similar to those in question or any improvement upon them.
Instead of one liquid for cleaning,, sterilisation, or backward filtration, as above
described, I may use two or more consecutively, in which case, if desired, one may
clean, and one may sterilise, or each' in some measure discharge both functions, or
the combination do so by chemical reaction within the filters. Chloride of lime
solution followed by hydrochloric acid solution may for instance be used for this
ригрове.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is;-
(1). The construction of filters to give approximately a constant output con-
sisting of a pump limited to a speed necessary for such outout or a cock or orifice

page_text: on the inlet passing only such output in combination with a vacuum or pressure
gauge indicating the variations of effective motive pressure occurring in the pro-
duction of the output for the purposes and as described.
(2). Filters with inclined baffle-plates interposed in the direction of flow of
water carrying Kieselguhr or equivalent material for the purpose and as described.
(3). In filters a traversing sparge pipe with jets at various angles for cleaning
in the manner described!
(4). A filter with closed filtered water chamber in conjunction with an exhaust
pump for the removal of air before admission of liquid for backward filtration as
desoribed.
(5). The process of regulating the supply of water to filters consisting of the
limitation of the initial vacuum or pressure to the amount necessary to produce
the desired supply and cleaning at epochs determined by the subsequent rise of
the necessary vacuum or pressure as shown on the vacuum or pressure gauge as
described.
(6). The process of cleaning filters formed of hollow bodies with closed upper
ends consisting of the withdrawal of a large part of the air contained therein and
the replacing of it by a suitable detergent liquid as described.
Dated this 20th do- of Canterban 1007