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Argus I for Group 'B' Roads

Single piece dome refractor lantern with outer bowl

Crompton Lamps :-

60/200W.Tungsten filament(GLS)
80/125W.Mercury Electric Discharge(MB/U)
80/125W.Mercury Fluorescent Discharge(MBF/U)

With an outer bowl to seal the interior against dust and weather, this simple but robust lantern embodies the following features:-

  • Automatic focusing of lamp and registration of refractor.
  • Totally enclosed quick release clips for removal of refractor.
  • Outer bowl available in glass or 'Perspex'
  • Internal single piece refractor in three distributions.

Lamp Wattage
and type
Complete Lantern Catalogue No.
60/200 GLSB.C.S121ASS121ANS121AX
60/200 GLSE.S.S121BSS121BNS121BX
80/125 MB/U
80/125 MBF/U
3-pin B.C.S121CSS121CNS121CX
For 'Perspex' instead of glass outer bowl add suffix 'P' e.g. S121 AS/P.
Unless otherwise specified standard ¾ B.S.P. tapping will be supplied.

Dimensions, Tapping & Height
Height12 5/8"
Tapping B.S.P.¾
Minimum length of thread required7/8"
Weight8 ¾lbs.

Refractor Catalogue Numbers

1. Construction

The skirt is cast with the body which is arranged for top entry and provided with three sets of tapped bosses for the fixing of the lampholder bridge assembly. This consists of a simple bridge piece, carrying the lampholder, with bayonet slots to engage fixing screws in the bosses. The bayonet slots allow the bridge to be change from one set of bosses to another or to be removed for wiring without the complete withdrawl of the fixing screws.

The body has two totally enclosed spring loaded clips for the retention of the refractor glassware. This is of the single piece dome type with prisms moulded on both its internal and external surfaces. A projection moulded on the neck of the refractor engages with a recess in the body casting and ensures correct angular location.

The outer bowl, which is held in position by three substantial fixing clips, is carried in a hinged retaining ring and is effectively sealed against the ingress of dust by two gaskets. Lugs on the ring engage with a self retaining wing nut fastening fitted to the lantern body.

2. Material And Finish

BodySilicon aluminium alloy LM6M, exterior finish aluminium, interior finish white
RefractorCrystal glass
Outer bowlClear glass or 'Perspex'
Bridge pieceMild steel cadmium plated
Hinge screwsStainless steel
Wing nutsBrass cadmium plated
Internal screwsMild steel cadmium plated

3. Distribution

Typical Polar Curves and an Iso-Candle diagram for the most popular 2/4116 non-axial refractor are given in Figs. 1 and 2.

FIG. 1
Polar distribution for 2/4116 refractor with 200W 2725-lumen lamp
A: In vertical plane through the centre of the main beam
B: Plan distribution of 80° cone

FIG. 2
Iso-candle diagram for 2/4116 refractor with 200 W. 2725-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 2/4116 Refractor

Beam Angle Horizontal170°170°
Beam Angle Vertical80°80°
Light output ratio77%76%
Light flux in lower hemisphere86%86%
Directional Intensity Ratio3.92.9