Asking The Right Questions About Cartridge Dust Collection
Choosing the best system for a given application involves research and attention to detail
Over the past decade, cartridge-style dust collectors have overtaken baghouses as the preferred technology for pharmaceutical dust collection. Combining maximum filtration efficiency with compact size and reduced pressure drop, a high efficiency cartridge dust collector will in most cases be the system of choice.
Choosing the best cartridge collection system for a given application, however, involves research and attention to detail. This article will review four key areas of investigation. By reviewing these topics with a knowledgeable equipment supplier and knowing the right questions to ask, engineers will be better equipped to make informed dust collection decisions.
1. Will the dust collector ensure compliance?
Engineers today must deal with an increasingly complex alphabet soup of regulations as the EPA, OSHA and other organizations continue to tighten air quality and safety requirements. Meeting these requirements should be first and foremost in any dust collection game plan. Failure to comply may result in fines, production shutdowns or costly litigation. In one recent case, a federal jury awarded $20.5 million to the plaintiffs in a lawsuit involving workplace air quality.
Continuous Liner Discharge System
Personal protection involves understanding the toxicological properties of the material, reviewing the Occupational Exposure Limit (OEL) and performing a risk-based exposure evaluation to determine the methods for proper control. In many cases, some level of isolation and containment is required due to the fact that the pharmaceutical dust is extremely potent and must not be released into the surrounding environment while being captured.
How can engineers know if dust collectors will comply with OEL? The equipment supplier should provide a written guarantee stating the maximum emissions rate for the equipment over an 8-hour time weighted average (TWA).
Engineers should also become familiar with the National Fire Protection Association's new "NFPA 68 Standard on Explosion Protection by Deflagration Venting", which provides stringent and mandatory requirements for dust collection applications involving explosive dusts. The change from a guideline to a standard is enforced by OSHA, which in October 2007 launched a National Emphasis Program focusing on the safe handling of combustible dusts.
Deflagration and explosion potential exists with most active pharmaceutical ingredients (APIs). Control measures such as explosion venting, chemical suppression and isolation systems may be required depending on the physical characteristics of the dust relating to Kst (a measure of the rate of pressure rise or deflagration index of a dust cloud), MIE (Minimum Ignition Energy) and the location of the collector. When explosion vents are required, they must be vented to the outside by either placing the collector outdoors or ducting the vent exhaust a specified distance through the building structure.
Many plants will have to install updated explosion venting equipment in accordance with NFPA standards.
Camfil Farr APC recommends use of an independent professional engineer to specify what explosion protection is required for a given material as it relates to standards in NFPA, ATEX and the major insurance carriers.
The new directives are significant because many plants will now have to install updated dust collection/ deflagration venting equipment or chemical suppression equipment that is manufactured in accordance with NFPA standards to ensure compliance.