Reverse osmosis water purifier

A reverse osmosis water purifying device is provided with a flush water restrictor which serves to provide a suitable back pressure on the reverse osmosis membrane in order to affect the purification process. The device is designed for attachment to any source of pressurized water. The restrictor device consists of a capillary tube sized to provide a suitable ratio of flush water to purified water. A ball-type check valve surrounds the capillary tube at its point of exit and the ball valve may be dislodged in order to flush the membrane. The core of the membrane assembly is filled with activated charcoal in order to provide for a more efficient and complete purification.

BACKGROUND OF THE INVENTION 
With the national trend toward the use of natural food products and the 
like in recent years, many people have increasingly sought alternatives to 
the tap water generally available. Such alternatives consist of either 
buying mineral, spring or distilled water or in the alternative to purify 
one's tap water to a more satisfactory level. Of the home purification 
devices presently available, most fall into one of two categories. First, 
many home distilling units are available, and while these are capable of a 
high degree of purification, they suffer from the drawback that energy is 
required to run them which consequently adds to the cost of the water in 
addition to the fairly high initial cost of such units. The second 
category of purifiers are generally those of the activated charcoal type 
which, although inexpensive and fairly efficient, do not remove enough 
impurities to provide truly healthful water. 
Various reverse osmosis water purifiers have been proposed and built in the 
past, the principle being well-known. Such prior devices are typified by 
U.S. Pat. No. 3,695,446. Such devices tend to be fairly bulky and, in 
addition, have been suited mainly for commercial use in that they have not 
presented a construction which a consumer could easily disassemble and 
reassemble or which is suitably compact for home use. The prior art 
devices also do not provide an apparatus which is easily operated by the 
consumer and which may be easily cleaned or flushed in order to extend the 
life of the reverse osmosis membrane. Also the prior art devices have 
tended to be bulky and expensive and aimed mainly at the commercial 
market. 
It is therefore an object of this invention to provide a reverse osmosis 
purifying device which may be manufactured inexpensively and used by the 
consumer in his or her home with a minimum of maintenance, expense and 
difficulty. It is further an object of this invention to provide a device 
which may be easily flushed in order to clear out residue build up from 
the reverse osmosis membrane and which may be easily adjusted to match the 
prevailing water condition in the area of where it is being used. 
SUMMARY OF THE INVENTION 
A cylindrical housing is provided which contains a spirally wound reverse 
osmosis membrane cartridge. The purified water spirals into the center of 
the cartridge while the feed and flush water runs axially between the 
layers of the cartridge. In order to properly utilize the reverse osmosis 
membrane, a substantial pressure must be placed on the feed water which is 
generally equal to the pressure of the water coming out of the tap. In 
order to do so, a back pressure must be created at the flush water outlet 
by means of a restrictor. The restrictor is formed by utilizing a 
capillary tube of substantial length and sufficient to restrict the flow 
and provide the suitable back pressure for operation of the reverse 
osmosis membrane. The capillary tube is coiled in the bottom of the 
housing. The core of the reverse osmosis membrane is filled with activated 
charcoal which serves to further purify the water before it is passed out 
at the device. A plug is provided at the bottom end of the housing for 
draining and recharging the charcoal in the center. The capillary tube of 
the restrictor passes through a small rubber ball check valve wherein the 
ball is normally held against its set by the tap water pressure. When it 
is desired to flush the device the check ball is dislodged from its seat 
by means of a small tube manipulable from outside the device in order to 
push the ball away from the seat and allow water to flush freely through 
the device thereby carrying away the salt and other residue build up from 
the reverse osmosis membrane surface thereby prolonging unit life as well 
as producing better results. The flush valve also can be used to release 
pressure in the unit when it is wished to disconnect the unit from the 
faucet or other source of pressurized water thereby preventing splashing 
of the user. 
These and other objects and advantages of this invention will more fully 
appear from the foregoing description made in connection with the 
accompanying drawings, wherein like reference characters refer to the same 
or similar parts throughout the several views.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to FIG. 1, the reverse osmosis purifying device generally 
referred to as 10 is comprised of a generally cylindrical housing 12 
having an upper half 14 and lower half 16. The inlet fitting 18 of the 
device 10 is connected via inlet hose 20 to faucet 19 by means of a 
conventional snap-on faucet connector 22. An outlet fitting 24 allows 
finished, purified water to flow through outlet tube 25 into any storage 
container desired. Flush water outlet fitting 68 is connected by means of 
hose 76 to a drainage source which can be a conventional sink drain. 
Referring now to FIG. 2, upper housing 14 consists of a generally 
cylindrical portion having at one end threaded connector 14a for 
connection to the bottom cylindrical section 26 at bottom threaded portion 
16a. An o-ring 15 is located therebetween in order to assist in sealing 
between the two halves. Upper end wall 14b has depending therefrom outlet 
locating tube 50 and an outlet passage 88 located therein. At the bottom 
end 50a of outlet tube 50 a screen 84 prevents charcoal and the like from 
passing into the outlet as will be more fully described hereinafter. A 
membrane assembly generally 30 takes the form of a cylinder having a 
hollow core 46. Inlet fitting 18 is threaded into the side of lower 
housing 16 and there is provided between the outside of core assembly 30 
and housing 12 an inlet flow passage 26 which runs about the circumference 
between housing 12 and membrane assembly 30. A seal 28 is located towards 
the lower end of the membrane assembly 30 and serves to prevent the inlet 
water from traveling downwardly past that point. An upper retaining cup 56 
retains the upper end of membrane assembly 30 in relation to housing 12. 
The membrane assembly 30 consists of a spirally wound membrane laminate 32 
comprised of two layers of reverse osmosis membrane 32a and 32c 
sandwiching a felt-like material 32b. Such membrane assemblies are 
well-known in the art and can be formed of acetate or other materials. 
When water under pressure is placed against the sides of the membrane 
sandwich, due to the pressure differential caused by the water in felt 
material 32b being under no appreciable pressure, pure water will migrate 
through the membrane layers 32a and 32c into the felt spacer 32b where it 
will spiral inwardly as shown by the arrows to a pure water exit 40 
adjacent core 46. Core 46 has a number of apertures 48 which allow the 
pure water to flow inwardly therethrough. While the pure water flows in a 
spiral fashion around the spirally wound membrane, the feed water which 
becomes the flush water as it passes downwardly through the assembly flows 
axially through the device as shown in FIG. 2. The layers of membrane 
laminate 32 are kept apart by a screen-like member 34 which allows the 
feed water to flow between the layers of membrane laminate under pressure. 
One layer of the membrane sandwich is sealed to an adjacent layer by an 
outer seal 38 in order to prevent intermixture of the purified and flush 
and feed water and similarly inner seal 36 performs the same function at 
the inner end. The outer circumference of membrane assembly 30 is coated 
so as to prevent any permeability other than through the ends, those being 
namely feed water inlet 42 and flush water outlet 44. 
Retaining end cup 56 encircles and locates the upper end of membrane 
assembly 30. Cup 56 is comprised of cylindrical surface 56a depending from 
circular portion 56b. Water flows through inlet passage 26 into inlet 
chamber 54 at the upper end of the device. This chamber is stiffened by 
means of triangular ribs 60 shown in FIGS. 2 and 3. Cylindrical member 50 
has a plurality of axially extending notches 58 and inlet screen 52 is 
wrapped about member 50 in order to screen the incoming fluid from 
particles and the like. Notches 58 communicate with notches 56d of cup 56 
which are separated by ribs 56c as shown particularly in FIGS. 4, 5 and 6 
in order to provide communication with the inlet end 42 of membrane 
assembly 30. The lower end of membrane assembly 30 abuts against bottom 
wall 16a which has formed therein a toroidal shaped flush and outlet 
cavity 62. Outlet cavity 62 has coiled therein capillary tube 64 having a 
free end 64a with screen 65 located thereover. Capillary tube 64 is coiled 
in cavity 62, passes through outlet check ball 66 and into outlet tube 76. 
Check ball 66 is a small rubber ball valve having a passage through which 
capillary tube 64 passes. Check ball 66 is located in cylindrical check 
ball passage 72 in outlet fitting 68. A conical check valve set 70 
provides a surface against which check ball 66 rests when under pressure 
to prevent flow thereabouts except through capillary tube 64. A flush 
actuator 74 consists of a small piece of tubing through which capillary 
tube 64 passes and which is flared at end 74a to provide a means by which 
an operator may easily grip flush actuator 74 and press inwardly whereupon 
inner end 74b of flush actuator 74 dislodges check valve ball 66 from 
check valve seat 70 and allows the device to flush in a relatively 
unimpeded fashion out outlet tube 76. 
A threaded plug 78 is threadably located in bottom wall 16 of housing 12 
and has a slot 78a therein for engagement with screwdriver, coil or the 
like in order to facilitate removal. Plug 78 seals against o-ring 80 so 
that plug 78 provides access to the inside of core 46 which is filled with 
activated charcoal 82 which acts as a further filtering agent. Plug 78 
allows the charcoal to be removed and recharged without extensive 
disassembly of the remainder of the device as such removal and replacement 
is periodically required in order to insure proper performance. Screen 84 
is sandwiched between the upper ledge 46a of core 46, sealing o-ring 86 
and the bottom end 50a of cylindrical member 50 in order to retain the 
charcoal in the core area. 
FIG. 7 discloses an alternative embodiment of the inventive device wherein 
provision is made for direct snap-on engagement of device 110 to a faucet 
(not shown) by means of snap-on fitting 122. While device 110 is somewhat 
smaller than the previously described embodiment, such smaller sizes are 
required in order for the device to be accommodated within various 
household sinks. Thus water incoming through passage 154 communicates 
through passage 158 with the upper end 142 of cartridge assembly 130. The 
lower end of the device is substantially similar to that shown in FIG. 2 
including the flushing mechanism. Cotton filter material 185 is located in 
the outlet passage 188 which assists in locating and retaining the 
charcoal in the core chamber as described above. Water exits outlet 
chamber 188 by means of outlet tube 124 as shown in FIG. 7. 
Due to the nature of the membrane, once it has been wetted, it must remain 
wet (between uses) in order to remain effective. To keep the membrane wet 
one may place a simple cap or plug over the outlet hose 76. The other two 
ports of the device may be sealed by means of a plug 180 shown in phantom 
in FIG. 7 and which fits into snap-on fitting 122. Plug 180 has an 
aperture 181 therein for reception of pure water outlet hose 125. Of 
course the same plug construction may be used with the embodiment of FIGS. 
1-6. 
In operation, the device is hooked to a water faucet, the water travels 
inwardly through inlet tube 20, inlet fitting 18, and thence into inlet 
passage 26 surrounding membrane assembly 30 whereupon it travels upwardly 
into inlet cavity 54. There, after passing through inlet screen 52 
(ideally about 50 mesh) the water passes downwardly through notches 58 and 
slots 56d in cup 56 and into the inlet end 42 of membrane assembly 30. The 
tap water which is typically at a pressure of anywhere from 30-125 psi 
causes pure water to force its way through the membrane and into the 
membrane 32a and 32c and into the felt area 32b whereupon it spirals its 
way into the center as shown in FIG. 8. Thence, the pure water passes 
through apertures 48 and core 46 whereupon it passes through activated 
charcoal 82 which removes the final traces of chlorine, organics, 
chloroform and the like. The purified water then passes through outlet 
filter screen 84 and thence through outlet passage 188 and outlet tube 25. 
On the other hand, the feed and flush water travels downwardly as shown in 
FIG. 2 through the screen member 34 located between the membrane laminate 
layers until it enters outlet cavity 62. In order to maintain a suitably 
high pressure on the reverse osmosis membrane, a restriction is needed in 
the outlet so that the proper pressure can be exerted on the membrane. In 
the instant invention, a capillary tube serves this function and is easily 
adjustable to fit varying water types and conditions. Typically, the 
capillary tube is formed of 0.020 inch ID tubing which is coiled about the 
outlet cavity 62. The length of the capillary tube 64 then determines the 
rate at which water will flush through the device. If one starts with 
relatively clean water having, for instance, 300 ppm dissolved solids, 
then one would provide a capillary tube length of approximately four to 
five feet. Since this water is relatively clean, there is no need to flush 
a lot of water through the system in order to keep the membrane surface 
clear. Thence, with the relatively pure water to begin with and the large 
amount of restriction, the device will yield approximately one gallon of 
pure water for every two gallons of flush water passing through the 
system. On the other hand, should one start with a water that contains 
more contamination of say 3,000 ppm dissolved solids, one would cut the 
capillary tube to have a length of approximately one foot thereby 
providing less restriction and yielding approximately eight gallons of 
flush water for every gallon of pure water produced. With such relatively 
impure feed water, it is desirable to provide a certain amount of natural 
flushing action by lowering the restriction. In any case, whether with 
relatively pure water or relatively impure water, it is desirable to 
periodically provide a flushing action much greater than that provided in 
the normal operation of the device in order to pass a large amount of 
water over the surface of the membrane in order to clean off salts and the 
like which may become deposited there. In order to do so, all a user need 
do is press on the flared end 74a of flush actuator 74 then press inwardly 
thereby pressing end 74b against check ball 66 and moving it away from 
conical check seat 70 thus allowing a much larger amount of water to flow 
out of the system than would normally be allowed by the capillary tube. 
This flushing system is also useful in that even if the faucet to which 
the unit is attached is shut off, the unit will retan a high amount of 
internal pressure. In order to bleed off this pressure so the unit may be 
removed from the faucet without splattering, all one need do is actuate 
the flush mechanism as described above. 
While the preferred embodiments of the present invention have been 
described, it should be understood that various changes, adaptations and 
modifications may be made therein without departing from the spirit of the 
invention and the scope of the appended claims.