Z.8433/4 Lantern. Sectional scale drawing. The iso-candle is based on an average lamp light output through life from a 250 watt OSRAM H.P.M.V. lamp. (7,250 lumens) . 250 w. 400 w. Directional intensity ratio 2.5 2.2 Light above horizontal 2% 2% Light output ratio 60% 60%

"BLOWN CUT-OFF" LANTERN The lantern opened to show lamp mounting, magnetic deflector and focusing.

"Blown Glass Cut-Off" Lantern.

Use Main road lighting, roundabouts, roads in the vicinity of airfields, dock and waterside lighting. The lantern has a cut-off distribution which virtually eliminates glare. The peak candle power is about 70 deg. to teh vertical and above this the intensities fall off very rapidly.

These characteristics make the lantern particularly suitable for waterside lighting where for navigational purposes it is generally necessary for ligth to be shielded. Excellent results are also obtained at roundabouts where a cut-off distribution assists visibility.

It is particularly important that lighting on roads near airports should not be mistaken for any of the airfield lighting and on such roads it is therefore genreally necessary to use lanterns giving this form of cut-off light distribution. Lanterns should be mounted at 25 ft. and spaced not more than 95-100 ft. apart, road width up to 50 ft.

Lamp

Mounting Side entry. Requires a minimum length of 16 in. horizontal unthreaded 1¼ in. gas barrel. When fully home, two 7/16 in. Allen type grub screws grip the barrel.

Lantern Body Die-cast light alloy body. Totally enclosed lantern. The body carries terminal block, wiring, magnetic deflector, over reflector, focusing gear, lampholder and lamp steady. An earthing screw is provided.

Lampholder Porcelain G.E.S. wired with heat-resisting wire to a terminal block.

Over Reflector Immediately above the lamp is a non-magnetic polished reflector.

Magnetic Deflector On the reflector plate is mounted the magnetic deflector which is in series with the lamp and consumes 1 watt. The use of a magnetic deflector enables a MA/H lamp with a hard glass outer jacket to be operated at the same efficiency as the normal MA/V lamp.

Focusing Three focal positions are provided giving main beam at 60 deg., or 65 deg., or 70 deg.

Optical System
The glassware is a one-piece blowing, the upper portion being silvered, copper and lead-backed whilst the lower half has a slightly rimpled surface. The contour of the silvered portion has been very carefully designed to make maximum use of light from the lamp. Two stainless steel expanding springs act as an addition support for the glassware.

Weathering Finish The light alloy used is specially selected for its resistance to corrosion. Further protection is obtained by the use of a suitable primer, undercoat and matt aluminium finish top coat.

Erection Instructions Full erection and focusing instructions are enclosed with each lantern.

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