The Gamma Series of centrifugal roof units is generally used in ducted systems for a wide range of exhaust applications. Construction Cowls are of UV-stabilised plastic. Steel components have a corrosion-resistant finish. Bird-mesh guards are fitted as standard on size 284 and above. Backward-curved centrifugal impellers. Motors Type - external rotor, squirrel cage induction motor. Electricity supply - 220-240V single or 415V three-phase, 50Hz. Bearings - sealed-for-life, ball. Speed-controllable using electronic or auto-transformer controllers except CE316. Internal Thermal Protection Thermal protection is supplied as standard on all units. Auto-reset is fitted to units up to '28.' and manual-reset for size '31.' onwards. Testing Air flow tests to BS848:Part 1, 1980. Noise tests to BS848:Part 2, 1985. Special Features Can be mounted at angles up to 30°. Twin fan units to give 100% stand-by capacity can be provided for vertical discharge arrangement in a limited range of sizes. Refer to our sales department for details. Backdraft dampers are an optional extra with single fan units and standard supply with twin fan units. The pressure loss must be added to the system pressure when making selections. Supply air units can be supplied; see pages D-30/33 for selection data.