Fire and Smoke Testing
If dampers are expected to control smoke and air, it should be specified in the project's design by indicating the leakage amount allowed to pass through. Historically, Underwriters Laboratories 555S or Air Movement and Control Association laboratory methods are used to determine test procedures and leakage requirements.
Fan isolation or equipment room dampers generally require the National Fire Protection Agency exposure test. In addition, TVCDs could require fire ratings because they might be located inside equipment rooms with combustible items.
Generally, fire ratings are to be tested in accordance with British Standard 476-pt 20 fire tests for building structures and material. Dampers rated by British standards have shorter blade lengths and are built differently than NFPA qualifiers. British standard requirements limit gap or see-through during fire tests, caused by blade sag, frame deformation and blade rotation.
he longer the blades on TVCDs, the more mass and weight need to be supported during horizontal testing. To combat the effects, blade length and material thickness have become shorter and lighter to prevent premature gap exposure and extend rating time.
It's not uncommon for tested dampers to pass four-hour exposure requirements. Fire rated dampers may need sealing devices since they may be used for smoke control. Since British standards don't recognize air leakage requirements during fire tests, it's up to designers and system owners to request them.
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