IMPROVEMENTS IN FILTERS FOR WATER AND OTHER LIQUIDS
Year: 1878

page_text: PROVISIONAL SPECIFICATION left by Henry Rawlings at the Office of the
Commissioners of Patents on the 23rd March 1878.
HENRY RAWLINGS, of No. 108, St. Martin's Lane, Westminster, Filter Manufacturer.
"IMPROVEMENTS IN FILTERS FOR WATER AND OTHER LIQUIDS."
My Invention relates to further improvements upon the Invention the subject of
former Letters Patent, No. 1053, granted to me and dated March the 23rd, 1875.
My present Invention relates to a better means for cleaning filters by a reversing
action with filtered water, when the water requiring filtration contains much sedi- "
mentary matter or dirt; to revivifying the filtering material by aeration; also to
provide a better arrangement for portable filters and for those used on shipboard, or
for travelling purposes.
In filters with a reversing or flushing action the almost invariable arrangement
is to flush them with the same dirty or impure water that is passed through the
filter to be purified, thus contaminating the filtering material at the very point
whero it is most essential that no contamination should exist.
My Invention relates to an efficient incans for flushing them with filtered instead
of unfiltered water. For so doing I construct pressure filters in pairs to be used
alternately, and joined together by a pipe at the top, with a stop-cock or valve
between then).
When requiring to be flushed the water which has been purified by passing
upwards through one filter will, by opening the stop-cock or valve in the connecting
pipe, be made to pass downwards in the other filter, carrying the accumulated
grosser impurities with it, and escaping by a valve or tap at the bottom of that
filter. After this has been sufficiently done, and the connecting stop-cock closed by
another and smaller pipe attached to or near the filtered water outlet at one end,
and to the upper part of the filter at the other end, a current of air will be drawn
through the filter not in use, for so long a time as the water runs from that tap a
sucking action will always be present in that pipe, drawing air through the filtering
material, which air enters through the flushing-ont valve or tap, and thus to a great
extent revivifies the filtering material by aeration.

page_text: Where only a single filter is used it may be flushed from a receptacle at a higher
level, or otherwise forced through by pumping or other pressure.
In filters for use on shipboard or for travelling, as the process is generally a very
slow one, requiring a large space for the collection of the filtered water, much
valuable space is occupied. By the adoption of the ascending principle, and only
using the most powerful filtering materials, such as animal charcoal, to purify the
water in a constant stream, the storage of filtered water is unnecessary, and as in
this class of filter only small amounts of water are generally required at a time the
unfiltered water space also may be greatly reduced, thus economizing space to the
utmost.
I construct two cylinders or other convenient forms, one within the other, the
inner one of which contains the filtering material, and having holes in the lower
portion to admit the water, which, after passing upwards through the filter, is
discharged by a syphon pipe on the outside of the outer cylinder or beneath it.
The space between the two cylinders contains the unfiltered water, and access is
given to the filtering material by a cap; or the outer cylinder may be dispensed
with, and a communication made with the charcoal chamber by means of a pipe
with a funnel-shaped top for the unfiltered water to be poured into. By this
arrangement only so much water need be placed in the filter as may be required at
one time, as the syphon will entirely empty it, thus always keeping the filtering
material in contact with the air when not in use.
Those arrangements also offer conveniences for applying wet cloths for refrigerating
purposes.
Household filters may also be constructed in the same manner, but with an
enlarged water-holding space and other modifications to suit circumstances.