Cleaning Copper Tube Heat Exchanger
- Set up a 30 or 55 gal barrel ½ full of water, and a recirculation pump, to pump into the heat exchanger, and return back from the heat exchanger to the barrel. The input should be at the bottom; the output should be at the top.
- Add ½ quart or so of silicone based antifoam; then add 5 gal, or as directed (depends upon size of system), of RTA 9947 to the barrel.
- Start circulation to the heat exchanger with the pump.
- Test the % acid content of the returning solution. It should not go higher than 3 to 5% for the initial injection period.
- Test every 15 minutes. When the % acid decrease is less than ½% between tests, add more RTA 9947, always keeping below the 3% total acid concentration.
- Continue to add more RTA 9947 until the % acid no longer decreases for a ½ hour period from the previous test. After the acid no longer reduces, the HE should be fairly clean.
- Dispose properly and safely of the solution in the barrel and in the system, and flush the system with water.
- Refill the barrel with water, add 1 qt to ½ gal of RTA 1130 (diluted 50%), or Caustic Soda 50%, and recirculate for 15 minutes.
- Make sure that the circulation water tests higher than 8.3 ph. (Add 1 drop of Taylor #638 reagent, or equivalent phenolphthalein indicator solution-test sample turns red if above 8.3 ph)
- Drain and rinse the system with water by pumping water through the heat exchanger.
Acid Test Procedure
Add 1 ml of cleaning solution to a 25 ml test tube with approximately 20 or 30 ml of water.
Add 2 drops of total alkalinity indicator (Taylor # 645, or equivalent) reagent. If the solution stays green, the cleaning solution contains relatively little acid.
If the solution turns red, add 5.0 N sodium hydroxide (NaOH), until the solution goes to green. Multiply number of drops required by 0.75% per drop (or the factor required on your acid test, which depends on the drop size).
Note-Control at a maximum of about 3% acid in the cleaning solution.