Trouble Shooting

Filter cloth

We have been able to increase lifetimes in many instances. One example is from 2 to 3 weeks to 2 to 3 months lifetime. Another example is from 3 days to over 3 weeks in chemical production. We do this by “fitting” the cloth to the application.

Please contact us for assistance in fitting your filter cloth for your application.

Vibration

Vibration in a centrifuge whether Inverting Filter Centrifuge, basket or peeler can come from a mechanical or process problem. Any evaluation should first start with running the machine empty from zero speed to maximum and checking the vibration. Instrument technicians should first verify that the vibration sensor and intrinsic safety barriers are all operational. If “empty” vibration levels are normal, you are looking at process problem. Remember that rotating equipment will have harmonics or the natural frequency of the machine matched to the rotational speed will show higher amplitudes of vibration. Processes should pass through these harmonics but not remain at them to fill or spin.

If “empty” vibration levels are running high, a mechanical check is necessary. First looking at the process end, then possibly system, bearing overhaul, etc.

Process Problem

You have heard of a home washing machine walking across the floor- it is usually what we call the “sneaker effect”. Once the liquid level in the washing machine goes down, the unbalanced load becomes apparent… sneakers or heavy blankets on one side of the machine. Same effect in a centrifuge but an uneven cake has developed during the filling cycle. If vibration is up in the spins after wash or final spin, the cake may have developed unevenly.

Troubleshooting this can sometimes be frustrating. Completing a grid with fill speeds can be helpful:

Varying filling speed and filling rate. Design of Experiment would dictate fewer – to be discussed in another article.

A CIC 800 or HF 800 Inverting Filter Centrifuge would have a table similar to this

 Fill Speeds

Fill Rates to be varied 800 1000
80 liters/minute
100 liters/minute
120 liters/minute

Average filling rate of an 800 mm Inverting Filter around 100-120 liters/minute. Then record the vibration data seen in the final spin. If necessary vary filling rate outside this range and speeds. Sometimes this can be challenging but a systematic analysis should yield the optimum speed and filling rate.

Have a process challenge in filtration, centrifugation?

Complete our Contact Form with your questions and we will be happy to review.