Neutral pH Cleaning Procedure – Heat Exchangers in Open Circuits

The procedure for cleaning heat exchangers in an open recirculating cooling system is as follows:

1. Isolate the exchanger and set up a circuit with an external tank and pump to circulate cleaning solution through the exchanger.
2. Determine the volume of the system to be cleaned.
3. Slug feed the neutral pH cleaner to the sump – a 10% solution is preferred for cleaning
4. Circulate the cleaner for 1 to 2 days
5. Sample the system several times per day and test for dissolved and suspended iron
6. If the total iron concentration reaches 8,000 ppm dump the cleaning solution and repeat the cleaning procedure
7. Samples should also be tested for pH – the pH will rise during the cleaning process
8. When the solution pH reaches pH 7.5 slug feed a 10 - 20% citric acid solution to neutralize
9. When the iron concentration reaches a plateau the cleaning is finished
10. Pump the cleaning solution out of the system. Flush the system and then replace with fresh make up
11. Place the heat exchanger back in service with treated recirculating cooling water as quickly as possible