Methods and composition for cleaning a heat transfer system having an aluminum component
View Patent ↗Disclosed herein is a method and treatment system for rapid cleaning and protecting of automotive cooling systems containing controlled atmosphere brazed aluminum heat exchangers. The method and treatment system can optionally include a conditioning (passivating) step. The treatment system can comprise three different parts: (1) cleaner or cleaning solution; (2) conditioner or conditioning solution; and (3) compatible CAB aluminum protective heat transfer fluid.
1. A treatment system for a heat transfer system comprising: a cleaner comprising an azole compound and an organic acid having a pKa of less than or equal to 5.0 at 25° C.; and a conditioner separate from the cleaner wherein the conditioner comprises a pyrophosphate, an azole, and an alkaline metal phosphate.
2. The treatment system of claim 1 , wherein the organic acid comprises oxalic acid.
3. The treatment system of claim 1 , further comprising an organic phosphate ester.
4. The treatment system of claim 1 , wherein the cleaner is combined with water to form a cleaning solution.
5. The treatment system of claim 1 further comprising a refill heat transfer fluid.
6. The treatment system of claim 1 wherein the cleaner is a solid.
7. The treatment system of claim 4 , wherein the cleaning solution has a pH less than or equal to 2.0.
8. The treatment system of claim 5 , wherein the refill heat transfer fluid is free of silicate.
9. A treatment system for a heat transfer system comprising:
a cleaner comprising an azole compound and an organic acid having a pKa of less than or equal to 5.0 at 25° C.;
a conditioner separate from the cleaner comprising a pyrophosphate, an azole, and an alkaline metal phosphate;
wherein the cleaner, when diluted with water, has a pH less than or equal to 2.0 at room temperature and the conditioner, when diluted with water, has a pH greater than or equal to 7.5 at room temperature.
10. A method of cleaning a heat transfer system comprising:
draining a heat transfer fluid from the heat transfer system;
filling the heat transfer system with a cleaning solution wherein the cleaning solution comprises an azole compound and an organic acid having a pKa of less than or equal to 5.0 at 25° C.;
circulating the cleaning solution through the heat transfer system;
draining the cleaning solution from the heat transfer system;
filling the heat transfer system with a conditioning solution comprising a pyrophosphate, an azole, and an alkaline metal phosphate; and
circulating the conditioning solution through the heat transfer system,
wherein the heat transfer system comprises a controlled atmosphere brazed component.
11. The method of claim 10 , wherein the cleaning solution has a pH less than or equal to 2.0.
12. The method of claim 10 , wherein the conditioning solution has a pH greater than or equal to 7.5 at room temperature.
13. The method of claim 10 , further comprising draining the conditioning solution and filling the heat transfer system with a heat transfer fluid free of silicate.