Pilot Plants in Hoods and Ventilated Enclosures

Hoods and ventilated enclosures are not always as effective as assumed. Follow these guidelines to safely install and operate pilot plants in hoods and ventilated enclosures.

Installing a pilot plant inside a hood is an increasingly common research practice in the chemical process industries (CPI). Small microscale pilot plants are often installed in standard laboratory hoods (Figure 1), such as bench hoods, or floor-mounted hoods (Figure 2). Larger pilot plants are often installed in larger commercially available hoods or custom-fabricated hoods (Figure 3). Most of these, particularly larger hoods, are floor mounted. Specially designed ventilated enclosures that lack a standard hood plenum but are intended to perform as hoods are also common. These are usually (but not always) floor mounted.

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▲Figure 1. Many small laboratory-scale pilot units are installed in a hood.

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▲Figure 2. Pilot plants can be installed in floor-mounted hoods, like the one shown here.

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▲Figure 3. The custom floor-mounted hood shown in this image was designed to contain several distillation pilot plants.

Regardless of the type of hood or ventilated enclosure used, its high ventilation rate is considered a prudent safety measure to avoid the accumulation of flammable gases and vapors and mitigate potential fire or explosion hazards. However, hoods and ventilated enclosures are not always as effective as assumed in hazard analyses. This article reviews some of the safety issues associated with installing pilot plants in fume hoods and discusses some guidelines for safe installation and operation of these systems...