mailing list
site map

Leo for Group 'A' Roads

Bowl Refractor Lantern

Crompton Lamps :-

250/400WMercury Electric Discharge(MA/V)

This light but robust lantern embodies the following features:-

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

EntryLamp Wattage
and type
Complete Lantern Catalogue No.
Top250/400 MA/VG.E.S.S391DSS391DNS391DX
Side250/400 MA/VG.E.S.S396DSS396DNS396DX
Unless otherwise specified 1¼ B.S.P. entries will be supplied.

Dimensions, Bracket Entries And Weight
Height18 5/8"
Side Entry B.S.P. (unthreaded) 1¼"
Minimum length unthreated tube required3¾"
Top Entry B.S.P.1¼"
Minimum length thread required1"
Weight19 ½lbs.

Refractor Catalogue Numbers

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.

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 prismatic bowl. A top reflector is however fitted to ensure maximum light output.

2. Material And Finish

Canopy, Bowl ring and Lampholder BracketSilicon aluminium alloy LM6M. Aluminium stoved enamel finish.
ReflectorVitreous enamelled steel
Toggle clipsSteel, cadmium plated
Hinge pinsStainless steel
Bowl retaining clipsMild steel cadmium plated
Bowl RefractorHeat resisting prismatic glass

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 Refractor Bowl No. 2/4140

Beam Angle Horizontal160°
Beam Angle Vertical75°
Light output ratio74%
Light flux in lower hemisphere84%
Directional Intensity Ratio2.8

FIG. 1
Polar distribution for 2/4140 bowl refractor with 400W 16800-lumen lamp
A: In vertical plane through the centre of the main beam
B: Plan distribution of 75° cone

FIG. 2
Iso-candle diagram for 2/4140 bowl refractor with 400W 16,800-lumen lamp.