Compressed Air Best Practices - October 2008 - (Page 53) Compressed Air Industry AUTOMOTIVE TRANSIT | 10/08 | Factor #2: Pressure Drop The next consideration is pressure drop across inlet filters. Pressure drop is simply the difference in vacuum between the inlet of the filter and the discharge of the filter. Pressure differential across inlet filtration can be important in that if it is excessive, there are higher costs associated with operation of the vacuum pump. High vacuum differentials result in a higher capacity requirement. In simple terms, the vacuum pump has to create a deeper vacuum to account for the loss across the inlet filter. If vacuum pump capacity is fixed, the result will be a loss of vacuum at production equipment. “In many cases,. the expected service life of a vacuum pump comes down to how well it is protected from incoming contamination.” Factor #3: Serviceability The final key component is serviceability. It is recommended that whatever design being used have elements that are easy to clean or change. Most vacuum pump applications have single inlet filter configurations. In this scenario, the vacuum pump must be shut down to change or clean inlet filter elements. A better arrangement is to install a dual- inlet filter system so that one side can be cleaned while the other side is in operation. In this manner, low differentials can be maintained throughout the production cycle and demand applications can realize maximum vacuum at the point of use. Also note that when servicing cartridge style filter elements, it is important to keep debris out of the pump inlet when the loaded element is removed from the filter housing. Conclusion Inlet filter design should not be taken lightly. The best course of action is to obtain a particulate sample and send it to a capable lab for analysis. They will provide a full report on particulate size distribution so that decisions can be made regarding media and filter configurations. Also, contact your vacuum pump manufacturer for information on how much and what size particulate their vacuum pump can tolerate. For very small particulates, specialty media such as HEPA (high-efficiency particulate air) or ULPA (ultra-low penetration air) may be required. Once this information is gathered, design the inlet filter for low-pressure drop and easy serviceability. The benefits to this process will be longer service life of vacuum pumps and extended production uptime. For more information, contact Dan Bott, Dan Bott Consulting LLC, tel: 251-609-1429, email: dan@dbott.com, www.danbottconsulting.com www.airbestpractices.com 53 http://www.danbottconsulting.com http://www.airbestpractices.com
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