Bowl Refractor Lantern with Inner Dome Refractor

Crompton Lamps :-

This light but robust lantern embodies the following features:-

• Enclosed dustproof construction.
• Smooth outer surface to bowl.
• Snap action toggle fasteners.
• Symmetrical or non-axial distribution.
• Top or side entry.

1. Construction

The canopy of this lantern, available in two versions, one for side and the other for top entry, is a robust but lightweight aluminium alloy casting. A central tapped boss with a locking nut is provided for the top entry version. In the case of the side entry lantern the bracket entry is cast integrally with the canopy and includes a bracket stop and moisture baffle. A drainage channel is also provided to lead any condensation from the bracket arm out of the lantern. Two Allen screws are used to secure the lantern to the bracket arm. Two Allen screws are used to secure the lantern to the bracket arm.

The outer prismatic bowl is carried in a light but strong cast aluminium alloy frame hinged on one side to the lantern canopy. Two snap action toggle fasteners are provided on the other side of the canopy to secure the frame when closed whilst, for the exclusion of dust, gaskets are interposed between the bowl and its frame and between the bowl frame and the lantern canopy.

Screwed to the inside of the canopy is a cast lampholder bridge piece. This is specially shaped so that, in the case of the top-entry lantern, no condensate can fall on to the lampholder or the lamp itself. The lampholder is supplied ready wired with heat resisting cable to a porcelain terminal block conveniently mounted near the bracket entry. A clearly marked earthing terminal is also fitted.

Light control is achieved primarily by the combination of inner dome refractor and outer bowl. A top reflector is however fitted to ensure maximum light output. The dome refractor is attached to this reflector which is provided with key hole slots so that both refractor and reflector may be removed from the lantern as one assembly and without the complete withdrawl of the retaining screws. These screws are so located that the reflector and refractor can only be inserted with the correct orientation with respect to the road.

2. Material And Finish

3. Focusing

Alternative sets of clearly marked bosses are provided for the mounting of the lampholder bridge so that the two sizes of lamp are accommodated in the correct focal position.

4. 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.

5. Optical Data For Non-Axial Lantern Type S401DV or S406DV

FIG. 1
Polar distribution for non-axial lantern type S401DV with 500W 8410-lumen lamp
A: In vertical plane through centre of main beam. B: Plan distribution of 77° cone

FIG. 2
Iso-candle diagram for non-axial lantern type S401DV with 500W 8410-lumen lamp.