Deionized Water
Guidelines
· All deionized water rinses should be tested for bacteria once per week according to the procedures in Section 12-2, Electrocoat Recirculated / Dip Rinses, Testing.
· Treat for bacteria when the deionized water rinses test positive (>103) two (2) consecutive times.
· Treat the entire deionized water rinse system.
· Use the total number of gallons in the rinse system, plus 10% for piping, to calculate the amount of biocide to add.
· Alternate biocide treatments. Kathon EDC 1.5% or other liquid biocide one time, silver nitrate (AgNO3) the next.
· Biocides (i.e. kathon, hydrogen peroxide, etc.) are contact killers. The biocide must come in contact with the bacteria to kill it.
· Maintain biocide level for 24 hours.
Dosage
See Section 12-4 for suppliers and recommended dosages.
Kathon EDC 1.5%(or equivalent) - Add 1 – 2.3 gallons of liquid biocide per 1,000 gallons of rinse system to be treated.
Example: The dosage for an electrocoat system with a 3,500 gallon recirculated deionized water rinse would be as follows:
3,500 gallons recirculated DIW rinse
350 gallons 10% for piping
3,850 gallons to treat
3,850 gals. ¸ 1,000 = 3.85 gallons of liquid biocide
This is assuming a treatment of 1 gallon of biocide per 1,000 gal of E-Coat.
Hydrogen Peroxide (H2O2)– Add 5 gallons of 30% hydrogen peroxide per 1,000 gallons of rinse system to be treated.
Example: The dosage for an electrocoat system with a 4,000 gallon deionized recirculated rinse would be as follows:
4,000 gallons recirculated DIW rinse
400 gallons 10% for piping
4,400 gallons to treat
(4,400 ¸ 1,000) x 5 = 22 gallons of 30% H2O2
Silver Nitrate - Add 0.33 lb. per 1,000 gallons of E/Coat system to be treated. This is equal to 39 PPM dosage. For infections >105, a higher dosage of silver nitrate may be required.
Example: The dosage for a 3,500-gallon DIW stage would be as follows:
3, 500 gallons recirculated DIW rinse
350 gallons 10% for piping
3,850 gallons to treat
3,850 gallons ö 1000 = 3.85 X 0.33 = 1.3 Lbs. Silver Nitrate