With proper maintenance and concentration control, metalworking fluids can last for years. It’s important to keep an eye on machining fluid sumps and systems, but, regardless, the fluid will eventually need to be changed out. The following signs call for a DCR, or “Dump, Clean, & Recharge”:

1. Low sump level: Level should be checked daily. Fluid will evaporate over time, increasing chemical concentration. This can be maintained with a refractometer and addition of fresh fluid, but a drastic change might be a sign of leakage. If draining is required to perform system repairs, a DCR will be needed.

2. Abnormal fluid: If the fluid has a visible amount of suspended dirt, tramp oil, or debris, it may no longer be salvageable. Small amounts can be skimmed off, but extreme changes in appearance is a key sign that replacement is needed. Gray or black fluid often means bacteria is present, whereas yellow or brown fluid may be a sign of excess tramp oil.

3. High microbiological level: Low pH is often an indicator of bacterial and fungal growth. This level can be maintained to an extent with biocides & fungicides (such as KATHON 886 MW, which can be purchased on our website here) but will require a fluid changeout if a critical level is reached. Strong, rancid odors are a sign of high microbiological concentrations.

4. Product change: If switching over to a new product, it may be incompatible with the existing fluid.

If you find that it may be time for a DCR, make sure not to miss the key steps highlighted below. Go over your plan in a meeting with all necessary personnel to ensure a smooth changeover!


1. Test the existing fluid and surrounding areas for microbiological levels prior to dumping to make sure all potential sources of bacterial & fungal contamination are removed.

2. Discuss rates or volumes of dumped fluid, cleaners, and rinse water with key waste treatment personnel, if needed, to confirm that this waste fluid volume can be properly disposed of.

3. Remove tools and parts from the production line to prevent any staining or residue.

4. Address any necessary repairs while system is down.


1. Check that a cleaner has been purchased and delivered, and proper concentration has been determined.

2. Confirm that the filtration system can handle the increased load of dirt and debris.

3. Determine if the cleaner should be added before or after the dump.

4. Sensitive components should be protected before the cleaning process begins.

5. Proper rinsing is important to minimize foaming of the new fluid. Check the pH of the final rinse and compare it to the fresh water to confirm that proper rinsing has been completed.

6. Add replacement fluid right away. If a clean system remains stationary for long, rust may develop.


1. Ensure the replacement fluid arrives on time and necessary concentration is determined.

2. Make sure water quality is good for recharge.

3. Confirm that all equipment is in place and functioning properly, with everything turned back on.

4. Make sure the fluid looks right and flows properly.

Following these steps should ensure a smooth DCR. To view and purchase our available cleaning and metalworking fluids, please visit us at https://www.quakerhoughtonconnect.com.

If you have any questions or are seeking product recommendations, don’t hesitate to contact us by phone at 1-888-872-1375 or email us at inquiries@qh-connect.com.