Issue link: https://www.e-digitaleditions.com/i/492796
Where will the dust collector be located? Dust collectors for tablet coating applications are usu- ally located indoors (photo), either in a maintenance or mechanical area adjacent to the Good Manufacturing Practice (GMP) space, or within the GMP space itself. If located within the GMP space, the dust collector must meet strict FDA requirements, just as all equipment in that space must, which may raise the costs of the collector. Less often, usually due to space constraints or local requirements, collectors are placed outdoors. If a com- bustible dust is involved, the collector will likely be equipped with an explosion vent, and you will need to calculate the explosion vent area required and how to properly direct the explosion to a safe location. Outside installations typically have longer duct runs, and thus cor- rectly configuring them takes on added importance to ensure consistent airflow from the coater to the collector. If incorrectly configured, the ductwork will lead to shorter filter life or blinding, which will cause the dust collector to malfunction and the coating system to fail. What is the best type of explosion-protection equipment? Explosion venting is the most basic and economical form of explosion protection, but it may not be an option if the collector is located within the GMP space and/or deep inside the building. In fact, that is where most coat- ing operations and associated dust collectors are, and that makes venting an explosion to an outside wall difficult. In these situations, and/or if the dust is harmful or toxic (particularly if solvents are used), the only option may be a chemical suppression system, which is much more costly than venting. See Figure 2. A chemical suppression system detects an explosion hazard within milliseconds and releases a chemical agent that extinguishes the flame before a deflagration can occur, protecting the dust collector from explosion. The inlet and/or outlet ductwork itself must also be protected from explosion. If chemical suppression is used on the dust collector, chemical isolation is typically used for the ductwork. Installed on the inlet and/or outlet ducting, it creates a chemical barrier that suppresses and isolates the explosion within the ducting and reduces the propaga- tion of flame. It also minimizes the pressure rise within connected process equipment. Mechanical isolation is another option. In these sys- tems, passive dampers or fast-acting valves prevent a deflagration from reaching upstream equipment. Determining which explosion-protection and duct-iso- lation methods are best for your coating operation 16 April 2015 Tablets & Capsules Figure 2 Explosion-protection methods a. Explosion vent b. Chemical suppression c. Chemical isolation d. Passive isolation valve (active mechanical isolation valves also available) Most dust collectors used with tablet coating operations are located indoors, as this one is. It includes two high-efficiency filter cartridges and a chemical suppression and isolation system.