Coolant reconditioning system

A two part system providing initial filtration of free oil and dirt followed by biological filtration with a copper wool and brass wool filter medium.

BACKGROUND OF THE INVENTION 
This invention relates to filter systems, and in particular to a filter 
system particularly useful for reconditioning water-soluble coolants. 
Metalworking oils are used in industries as diverse as machine shops and 
machinery manufacturing. Water-based cooling and lubricating oils are 
routinely sprayed into metal-cutting and shaping equipment. Because the 
oils, especially in water-soluble coolant form, are generally recaptured 
and recycled, they often end up containing a mixture of bacteria and other 
contaminates that increase machine operator health risks and corrode 
machinery. Because machines often spray coolants into the ambient area 
both in droplet form and vapors, all parts of the machinery are adversely 
affected. Also, it is common for machine operators to experience chronic 
dermatitis and lung problems from biological growth in water-soluble 
machine coolants. Historically, machine operators have tried to protect 
themselves with gloves and masks. Generally, this has not been practical. 
Another solution has been to add chemical agents formulated to kill 
bacteria to the coolant. However, bactericides are themselves harsh and 
toxic, presenting other dangers to machine operators. To protect machinery 
and machine operators, coolants must be frequently changed. This raises 
other problems involving disposal of bacteria-contaminated coolant as well 
as cost to frequently replace coolant. 
Economically speaking, the most important metal-corroding and 
coolant-destroying microbe are the anaerobic, sulfate-reducing bacteria. 
These bacteria produce hydrogen sulfides, which react with iron, corrode 
metals and destroy coolants. 
SUMMARY OF THE INVENTION 
The present invention provides a filtration system which removes 
particulate matter and free oil, and then eliminates bacteria in 
water-soluble coolants. The invention is particularly effective in 
removing anaerobic bacteria, thereby protecting machinery and machine 
operators as well as extending the life of the coolant with a resulting 
savings in time and money. The filtration system is a two part system 
providing initial filtration of free oil and dirt followed by a contact 
chamber with a brass and copper wool packed element. Applicant has found 
that substantially all bacteria in the filtered water-soluble coolant is 
eliminated. The use of brass wool and copper wool eliminates the toxicity 
of bactericides, copper leachate and chlorine solutions. The coolant may 
be reused without side effects, thereby eliminating disposal problems.

DETAILED DESCRIPTION OF THE INVENTION 
Referring to the drawings in detail wherein like elements are indicated by 
like numerals, there is shown an embodiment of the invention incorporating 
a filter system 1 constructed according to the principles of the present 
invention. The filter system 1 is a two part filter system comprised of a 
bag filter 2 for removing free oil and dirt from used, water-soluble, 
machine tool coolant 20 and a contact chamber 10 for controlling 
biological contaminants in the coolant 20. The bag filter 2 has a filter 
medium comprised of polypropolene, wool and cotton. The filter system 1 
has a pump 4 which draws contaminated coolant 20 into an input pipe 3, 
through the bag filter 2, and pushes the coolant through the contact 
chamber 10, and out of the filter system through an output pipe 5 as 
bacteria-free coolant 21. See FIG. 1. 
The contact chamber 10 is comprised of a hollow, tubular element having a 
bottom 11 from which cylindrical side walls 12 extend vertically upward, 
said element 10 being generally cylindrical in shape and having a 
longitudinal axis generally perpendicular to the bottom 11 of said 
element. The element 10 has a top 13 connected to said cylindrical side 
walls 12, said top 13, bottom 11 and side walls 12 defining an element 
interior 14. The bottom 11 has a retaining screen 15 attached thereto. A 
gasket seal 16 is attached to the element top 13 and to the bottom 11. The 
element interior 14 is packed with brass wool 17 and copper wool 18. In 
this embodiment of the invention the brass wool 17 is positioned 
vertically above (downstream) the copper wool 18. A porous disk 19 is 
positioned within the element interior 14 in a plane transverse to the 
central, longitudinal, vertical axis of the element 10. The porous disk 19 
prevents channelling through the element 10. See FIG. 2. 
Coolant 20 to be decontaminated enters the element interior 14 from the 
bottom 11 passing through the retaining screen 15. The coolant 20 upflows 
through the copper wool 18, porous disk 19 and brass wool 17 and exits 
through the element top 13 as filtered and decontaminated coolant 21. The 
copper wool 18 is highly toxic to bacteria, killing substantially all of 
the bacteria in the coolant 20. The addition of brass wool 17, which is in 
itself is also highly toxic to bacteria, has a synergistic effect 
substantially increasing the killing effect on the bacteria. The brass 
wool also picks up any dissolved or leached copper in the coolant stream. 
The brass wool 17 is a coarse grade with an average fiber width of 5 
mils/0.005 inch. The copper wool 18 is also coarse grade with a purity 
greater than 99.9%. In this embodiment of the invention, the brass wool 17 
and copper wool 18 are packed in concentrations of 0.05 ounces per cubic 
inch. A packing variation of .+-.15% appears to be equally effective. In 
this embodiment of the invention the filter media combination of brass 
wool 17 and copper wool 18 is 50% brass wool and 50% copper wool. 
Applicant believes that a proportion of brass wool to copper wool in the 
range from 25% to 75% of total filter media will also be effective. 
Copper is a highly effective bactericide. The addition of copper wool to 
the contact chamber provides a highly effective medium for killing 
bacteria. However, copper in wool form bleeds or leaches a small amount 
into the coolant stream. Brass is known to have an affinity for heavy 
metals. There is an advantage to also using brass wool because of its 
affinity for picking up dissolved and leached copper from the coolant 
stream. Therefore, if any copper leaches into the coolant stream, the 
brass will clean it out from the coolant stream. 
Brass wool has also been found by applicant to be highly effective in 
killing bacteria. Applicant has found that passing a coolant stream with 
an average bacteria coli of 100 colonies/100 ml through a filter element 
with only brass wool resulted in the killing of all of the bacteria 
colonies. The test was repeated four times with the same results. Of the 
different forms of brass experimented with, only brass wool appears to be 
100% effective in killing bacteria. Although brass wool in itself may be a 
sufficient filter media to kill bacteria, applicant believes the 
seriousness of the dermatitis and lung infections experienced by machine 
operators makes it desirable to add copper wool to completely eliminate 
all biological contaminants in the coolant stream. However, as may be seen 
from Table 1 below, there is a synergistic effect to using both copper 
wool and brass wool, with the brass wool increasing the effectiveness of 
the copper wool in killing bacteria. 
Applicant has found in tests that the combination of copper wool and brass 
wool is particularly effective in reducing anaerobic bacteria and 
staphylococcus. Table 1 demonstrates the effectiveness of brass wool 
filtration alone (B), copper wool filtration alone (C), and copper 
wool/brass wool combination filtration (C/B). 
TABLE 1 
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Anaerobic/Facultative 
Filtration Plate Count CFU/mL 
Staphylococcus/mL 
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1 W/O Filtration 
2,600,000 150,000 
2 B 160,000 3,700 
3 C 72,000 950 
4 C/B 33,000 310 
______________________________________ 
As may be seen from the table, brass wool or copper wool is effective in 
reducing bacteria. However, the combination of brass wool with copper 
wool, doubles the effectiveness of the copper wool. There is clearly a 
synergistic effect in using this combination. In the tests presented in 
Table 1, the sample used was a highly contaminated coolant that had been 
in use for over six months and was stored in barrels for disposal. For 
filtration tests, the sample was divided into four even portions. One 
portion was tested without filtration. The other three portions were each 
passed through a separate filter element, i.e., one comprised of brass 
wool (B), a second comprised of copper wool (C), and a third comprised of 
copper wool and brass wool (C/B). The filter sample portions were each 
recycled through their respective filter elements for 30 minutes. The 
results are illustrated in Table 1. The bacteria had been reduced by over 
99%. 
It is understood that the above-described embodiment is merely illustrative 
of the application. Other embodiments may be readily revised by those 
skilled in the art which will embody the principles of the invention and 
fall within the spirit and scope hereof.