Ask the Experts
The purpose of this blog is to provide a place for customers and the general public to ask questions about anything having to do with mist eliminators, how they work, recommendations and any other application specific questions. Our team of experts have extensive knowledge of all types of mist collectors and production environments.
To ask a question or make a comment, click on the comments link, someone will usually review and post your comment within 24 hours. If we find that the question is unique or would be of great service to others, we may make a new thread, starting with you comment. In any case, your question will be reviewed by several professionals, many of whom may choose to answer or add comments to existing answers.
Jason Wege Said,
December 13, 2006 @ 10:54 am
I am evaluating mist collecting systems, and have looked at Donaldson WSO, AirFlow systems and a Absolent ODF 2000. We have a Trion MP 1200 and an AirFlow system system in two other departments. They seem to work ok but they do blow some oil back into the plant. When measured at the outlet it measured .3-.5 mg/m3 We change the current filters every three months and this is about half way through the cycle. Is that performace what is expected from this type unit. The Absolent unit guarentees 2 years with out a filter change and guarentees less than .002mg/m3. The Airflow system is the same as our existing unit which has some benifits. I guess what are the pros and cons of each unit. The unit will be collecting mist from a water soluble oil concentration of about 7% and full synthetic mist at about 10% concentration.
Any input would be appreciated.
Jason Wege
Dave Said,
December 22, 2006 @ 4:33 pm
Jason,
In many applications, post-filtration may be needed, especially if you’re trying to adhere to a stringent cleanliness requirement. In many cases, simply adding a HEPA afterfilter could get you where you need to be, but ultimately it will be subjective to the application. In terms of an absolute guarantee on filter life, I would be a bit hesitant to guarantee a filter changing frequency, as it will depend on the individual application.
I would assume that whoever gave the "guaranteed" filter life must have thoroughly evaluated the project, measuring the amount of coolant being used, accounted for cycle times, calculated the concentration of fugitive mist, etc… Let’s say you have a leaky roof, and I provided a 5 gallon bucket - I can’t guarantee when you’ll have to dump the water out of that bucket, because I have no idea how much water is going to leak in - that’s probably not the best analogy, but you get the idea. 
Most performance guarantees will have some stipulation, or the performance will be rated based on a controlled environment, as in a testing facility. As testing procedures typically aren’t as intense as the actual operation, what looks good on paper may not necessarily apply out-of-the-box.
In my opinion, it would be most beneficial to address your machine tools with Electrostatic Pricipitators unless the application isn’t ESP-friendly. It’s no secret that there’s a considerable cost of ownership with media-based systems, and maintenance headaches with centrifugals, but they each have their own place in the machine shop. Of course, vendors who only carry centrifugals are invariably going to recommend centrifugals, and the same goes for the media vendors, and ESP vendors alike. On a personal note: being a provider of both media and electrostatic mist collectors, I would only use a media system if ABSOLUTELY necessary. ESP units will require more frequent PM scheduling than media units due to frequent cleaning, but having additional electronic cells on-hand quickly addresses that issue. The cost savings vs. having to constantly replace media filters in most cases makes it a no-brainer. In one particular instance, I visited a plant where they were spending in excess of $40,000 a month in media filters!
As for the average centrifugal unit, it’s not uncommon for the efficiency for finer mist to be lower, as its main function is to separate the heavier droplets. The media filter is included to catch the finer mist, but doesn’t always do a fantastic job. The balancing issues they have will invariably cause vibration issues, possibly leading to inaccuracies in part production. Another gripe maintenance techs have voiced is the job of essentially rebuilding the units when they have to replace the bushings and bearings every few years or so.
Bill Vogel Said,
July 25, 2007 @ 8:11 am
At our power plant we use a mist eliminator to remove the oil droplets from our turbine lube oil system vapor extactor. There is a need to impove the efficiency of this process and also to midigate the oil odor. The OEM of the turbine provided a separator some 30 year ago, and we are now trying to identify a system that will meet our current need. the lube oil system vapor extractor can provide a vacuum to the system of 1 to 5 inch H2O. any thoughts to new equipment.