Once foam builds up on a cleaning line, the spray pump starts running dry, the chemistry stops hanging onto the part surface, and no amount of rinsing water gets the rinse stage clean. The rework and the chemical consumption end up charged to the cleaning operation.
Chemi Tech makes defoamers for alkaline cleaners, acid cleaners and neutral water-based cleaning fluids, from the defoamer KM-500 series. Which grade to use depends on the surfactant system in the cleaner, the working temperature and the spray pattern. On spray lines the usual one is KM502, which holds up to strong alkali and acts quickly. Where it has to go directly into the cleaner formulation without clouding the system, KM suits better and is widely used on export-type products. Send over the cleaner formulation sheet and the process temperature, and we will run those items against each other before saying which grade to use, so you do not have to change a formulation round first.
Advantages of Chemi Tech Defoamers
The defoamer KM-500 series grades hold steady in both strongly alkaline and strongly acidic systems, without emulsion breaking or separating, and a cleaning bath is still clear after a week. The addition rate is low and puts no drag on cleaning power, so soil removal is not compromised. Knockdown is fast, so foam is held down as soon as the spray loop starts and the pump stops running dry. It withstands medium to high wash temperatures and is compatible with the nonionic surfactants commonly used. A further benefit of the low foam is that the rinse stage uses less water, and wastewater volume drops with it.
Chemi Tech notes that the behaviour above comes from a typical alkaline spray cleaning condition. Change the cleaner formulation or the process temperature and the results move. Run a small trial before switching the line.
Industry Pain Points and Solutions
Foam in a cleaner is hard to cure because the root of it is that foam is a born opponent of the surfactant, and suppressing it too hard costs cleaning power.
The first thing to surface when a formulation is touched is poor cleaning. Some chemistries hold the foam down and suppress wetting and emulsification along with it, so the oil and soil never come off. What Chemi Tech does is put detergency and defoaming into a single set of trials and read them together, rather than watching the foam height on its own.
What gets exposed next is bath life. If the defoamer is not compatible with the cleaner system, it separates the next day and the whole tank is written off early. What Chemi Tech does is run a compatibility check first, looking at both the standing and the heated state.
Once it is on the spray line there is a further point that does not hold, and static test conclusions often stop applying. Foam can be held down in a beaker and then re-form once the line runs at high circulation. What Chemi Tech does is run a dynamic circulation test at the customer's actual spray pressure and flow rate.
There is no need for you to test repeatedly. Compatibility, dynamic circulation, addition rate and addition point are run through in sequence by us, and adding one line to the batching record is all it takes.
Typical Conditions and Verification
Customer: a precision hardware component processor in Jiangsu, for an alkaline spray cleaning line and the rinse stage.
The plant recirculates its cleaning bath. The spray pump was running dry because of foam frequently, the workpieces occasionally carried alkali residue after rinsing, and rework before plating happened from time to time. The solution Chemi Tech's defoamers provided was this: working from the cleaner formulation and the spray parameters, KM-503 was selected from the KM-500 series and the addition points were set at both the batching tank and the circulation loop. After the change the spray pump stopped running dry, rinse-stage water consumption came down, and the re-inspection failure rate for alkali residue on the workpiece surface returned to normal. The hose on the cleaning line that had been used to wash foam away was put away.
FAQ
Will adding a defoamer affect cleaning power?
It can. Grades that suppress foam too hard suppress wetting and emulsification along with it, so the foam looks reduced while the oil and soil are not actually removed. The KM570 we supply to cleaner manufacturers is assessed on detergency and defoaming at the same time, and both sets of data are provided together.
Give the cleaner formulation and the spray conditions to our technical engineers, and we will run the compatibility and circulation tests, returning the results together with a recommended addition rate.