Corona I for Group 'B' Roads
Bowl refractor lantern
Crompton Lamps :-
| 45/60W | Sodium Discharge | (SO/H) |
This popular lantern is now available in two types, a standard lantern with accommodation for the lamp alone,
and a type 'SG' lantern with accommodation both for the lamp and the necessary CROMPTON lamp control gear. The
lanterns differ only in the depth of the top canopy and the arrangements of the internal reflector and fixings.
Features:
- High optical performance
- Dustproof construction
- Snap action toggle fasteners
- 'Perspex' bowl with smooth internal and external surfaces
- Hermetically sealed 'Perspex' refractor plates.
- Available for side or top entry.
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| STANDARD Lantern Accommodating Lamp only | 45/60 | Sodium B.C. | S290EX | S295EX |
| Type 'SG' Lantern with accommodation for Crompton Lamp and lamp control gear | 45/60 | Sodium B.C. | SG290EX | Not Available |
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Unless otherwise specified standard 1" B.S.P. tapping will be supplied. |
| Standard Type | 'SG' Type | DIMENSIONS, BRACKET ENTRIES AND WEIGHT |
| Height: | 10" | 11¾" | Side Entry: 1" B.S.P. Minimum length of unthreaded tube required | 4½" |
| Width: | 14" | 14;" | Top Entry: 1" B.S.P. Minimum length of unthreaded tube required | 1¼" |
| Length: | 18" | 18;" | Weight: Standard lantern, 10 lbs., S.G. lantern without gear, 17 lbs., S.G. lantern with gear, 30 lbs. |
1. Construction
The strength of this lightweight lantern is derived from its single piece cast canopy. This constitutes a weatherproof hood and
provides a rigid support for the optical system capable, in normal usage, of resisting all stersses due to vibration and windage. For pendant
suspension a canopy with a central tapped boss and locking nut is supplied. The alternative side entry canopy is secured by two
Allen screws and incorporates a bracket stop, moisture baffle and drainage channel to lead any condensation from the bracket arm out of the
lantern. Fixed to either canopy is a cast bracket, carrying a B.C. holder, a lamp support and an 'over-lamp' reflector.
The enclosing bowl is carried in a light but strong cast frame hinged to the canopy on one side and secured by snap action toggle fasteners
on the other. Gaskets are interposed between the bowl and its frame and between the bolw frame and canopy to prevent the ingress of dust.
The lampholder is wired with heat resisting cable to a porcelain terminal block mounted on the underside of the canopy adjacent to
bracket entry. A clearly marked earthing terminal is also fitted.
Light control is achieved primarily by means of prismatic 'Perspex' plates hermetically sealed to the inside of a 'Perspex' bowl so that
all prismatic surfaces are permanently protected from dust and all exposed surfaces of the bowl and plates, both inside and out, are completely
smooth to facilitate maintenance. Maximum light output is ensured by the overlamp reflector.
2. Material And Finish
| Bowl and Prismatic Plates | Clear 'Perspex' |
| Canopy, Bowl Frame & Lampholder Bracket | Silicon aluminium alloy LM6M. Stoved enamel finish. |
| Reflector | Electrically brightened aluminium |
| Lamp Support | Phosphor bronze cadmium plated |
| Toggle Clips and Hinge Pins | Stainless steel |
| Bowl Retaining Clips | Spring steel, cadmium plated |
| Gaskets | White felt |
| Lampholder | White porcelain |
3. Focusing
The lampholder and lamp support ensure that either size of lamp is correctly placed relative to the refractor plates.
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
| Beam Angle Horizontal | 180° |
| Beam Angle Vertical | 77° |
| Light output ratio | 80% |
| Light flux in lower hemisphere | 90% |
| Directional Intensity Ratio | 2.7 |
FIG. 1
Polar distribution with 60W 4200-lumen lamp
A: In vertical plane normal to lantern
B: Plan distribution of 77° cone
FIG. 2
Iso-candle diagram with 60W 4,200-lumen lamp.
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