More is better in some cases but when it comes to chemistry in industrial cleaning, using too much is costly and could indicate process problems as well.
First, there is the obvious cost of using more chemistry. Most aqueous cleaning chemistries range in price from $15 to $40 per gallon but may exceed $100 per gallon. Excessive usage is going to have an impact. Using more chemistry than needed leads to a requirement to increase rinsing to remove excess chemistry left on the cleaned parts. Increased rinsing requires more water and, in the case of heated rinses, heat. But the added cost does not end there. Using more chemistry also increases the cost of disposal of both spent cleaning solution and rinse water.
The need to use a high concentration of chemistry may be an indicator that the chemistry is wrong for the application. The likelihood of this increases when it is necessary to exceed the chemistry provider’s recommended concentration in order to get parts clean. In most cases the recommended concentration range is already quite generous.
So how do you avoid excessive chemistry use?
- Experiment with concentration. I have seen an alarming number of instances over the years where far more chemistry was being used than was needed. In most cases, the cleaning liquid becomes fouled beyond further use by contaminants removed from parts long before the chemistry is depleted. Apply chemistry wisely – – Don’t just go blindly with the recommended concentration. Try using less than the recommended concentration and see what effect it has on cleaning. It’s easy enough to add more chemistry if you get a bad result. But you’ll never know unless you try.
- Experiment with tank life. Establish a dump cycle and stick with it. Operate without refreshing chemistry until cleaning starts to degrade. Subtract a safety margin from that (10 to 20%) to establish the dump cycle. Or, if you are using a refractometer, conductivity, titration, specific gravity, pH or other indicators to determine the need to replace chemistry, make sure that the numbers being used are appropriate for the chemistry and the application.
- Consider increasing temperature instead of chemistry. Most chemistry works better at higher temperature and heat may be less costly than chemistry. Increased temperature may also make contaminants easier to remove. Remember, however, that some chemistries have temperature limits that must not be exceeded.
- In line with the previous point, always verify that bath temperatures are being maintained. Burned out heaters and inaccurate temperature sensors are more common than one would expect.
- Consider reducing the load on chemistry by using less or different process fluids upstream. Things to look at are coolants and cutting oils as well as buffing or lapping compounds and more.
- Consider precleaning. This might be as simple as a dip in hot water to remove excess oil prior to cleaning. Oil displaced by water can be separated using a gravity water separator and may in some cases be reused. Pressure washing or just allowing parts to drain off prior to cleaning are other considerations.
- Check with the chemical manufacturer to see if the chemistry can be replenished. Some chemistry has specific components that are depleted by the cleaning process. Replacing just these components extends the useful life of the chemistry often at reduced cost.
Finally, if you see a need to increase chemical concentration to achieve the desired cleaning result act aggressively to determine why.
To further explore the topic and others of related interest check out this blog.
– JF –