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Star III Lantern for Group 'A' Roads

Single piece dome refractor lantern

Crompton Lamps :-

300/500W.Tungsten filament(GLS)
125WMercury Fluorescent(MBF/V)

These simple but robust lantern embodies the following features:-

  • Automatic focusing of lamp and registration of refractor.
  • Bayonet fastenings for quick removal of refractor.
  • Single piece prismatic refractor in two distributions.

Lamp Wattage
and type
Complete Lantern Catalogue No.
300/500W GLSG.E.S.S160DSS160DN
125 MBF/VG.E.S.S160DSS160DN
Unless otherwise specified lanterns will be supplied with standard 1" B.S.P. tapping.

Dimensions, Tapping & Weight
Tapping B.S.P.1"
Minimum length of thread required1"
Weight15 lbs.

Refractor Catalogue Numbers

1. Construction

There are only four main parts, viz. body casting, lampholder bridge assembly, refractor and refractor retaining plate. The reflector is cast with the body which is arranged for top entry and provided with two sets of tapped bosses for the attachment of the lampholder bridge assembly. This consists of a simple bridge piece, carrying the lampholder, with bayonet slots to engage fixing screws provided in the bosses. They bayonet slots allow the bridge to be changed from one set of bosses to anotehr or to be removed for wiring without the complete removal of the fixing screws.

The refractor is of the single piece dome refractor type with prisms moudled on both its internal and external surfaces. Projecting studs from the refractor engage bayonet slots in teh refractor retaining plate which is itself screwed to the lantern body casting. The arrangement of studs and retaining plate is such that the refractor can only be assembled with the correct angular location.

2. Material And Finish

BodySilicon aluminium alloy LM6M, exterior finish aluminium, interior finish white and underside of reflector white
Bridge pieceMild steel cadmium plated
Refractor retaining plateMild steel sheradised
RefractorCrystal glass

3. Distribution

Typical Polar Curves and an Iso-Candle diagram for the most popular 2/4118 non-axial refractor are given in Figs. 1 and 2.

FIG. 1
Polar distribution for 2/4118 refractor with 500W 7930-lumen lamp
A: In vertical plane through the centre of the main beam
B: Plan distribution of 78° cone

FIG. 2
Iso-candle diagram for 2/4118 refractor with 500W. 7930-lumen lamp.

4. Focusing

The bosses to which the lampholder bridge should be fixed for each lamp size are clearly marked within the lantern.

5. Maintenance

The aluminium alloy from which this lantern is cast is highly resistant to corrosion in both industrial and marine atmospheres. Additional protection can be provided by occasional painting in service.

6. Optical Data For 2/4118 Refractor

Beam Angle Horizontal170°170°
Beam Angle Vertical78°80°
Light output ratio80%77%
Light flux in lower hemisphere90%81%
Directional Intensity Ratio5.62.6