Sirius for Group 'B' Roads
Bowl refractor lantern
Crompton Lamps :-
| 100/200W. | Tungsten filament | (G.L.S.) |
| 80/125W. | Mercury Electric Discharge | (M.B./V.) |
| 80W. | Mercury Fluorescent | (M.B.F./V.) |
This simple but robust lantern embodies the following features:-
- Automatic focusing of lamp and registration of refractor.
- Dustproof lantern construction.
- Single piece bowl refractor, with external surface mainly smooth, available in two distributions.
|
|
| 100/200W GLS | B.C. | S141AO | S141AV |
| 100/200W GLS | E.S. | S141BO | S141BV |
80/125W MB/V
80 MBF/V | 3-pin B.C. | S141CO | S141CV |
|
Unless otherwise specified standard ¾ B.S.P. tapping will be supplied. |
| Dimensions, Tapping & Height |
| Height | 13" |
| Diameter | 12" |
| Tapping B.S.P. | ¾"; |
| Minimum length of thread required | 7/8" |
| Weight | 7½lbs. |
| Refractor Catalogue Numbers |
| Symmetrical | 4115 |
| Non-Axial | 2/4115 |
1. Construction
There are only four main parts, viz. body casting, lamp holder bridge assembly, refractor bowl and bowl retaining ring. The reflector
is cast with the body which is arranged for top entry and provided with two 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 changed from one set of bosses to the other or to be removed
for wiring without complete withdrawl of the fixing screws.
Both types of refractor used with this lantern are of the single piece bowl type with prisms on the internal surface,
the external surface being smooth. Correct angular location of the bowls is ensured by the engagement of a projection
on the bowl with a cut-out in the bowl retaining ring.
The refractor, which is held in position by three substantial fixing clips is carried in a hinged retaining ring. Two gaskets effectively
seal the interior against the ingress of dust.
Lugs on the bowl retaining ring engage with a self retaining wing nut on the lantern body providing a simple yet secure fastening.
2. Material And Finish
| Body | Silicon aluminium alloy LM6M, exterior finish aluminium, interior finish white and
underside of reflector white |
| Bridge piece | Mild steel cadmium plated |
| Refractor bowl | Crystal glass |
| Bowl retaining ring | Silicon aluminium alloy LM6M, finish aluminium |
3. Distribution
Typical Polar Curves and an Iso-Candle diagram for the 2/4115 refractor bowl are given in Figs. 1 and 2.
FIG. 1
Polar distribution for 2/4115 refractor with 80W. MB/V 3000-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 2/4115 refractor with 80W. MB/V 3000-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 2/4115 Refractor
| MB/V |
| Beam Angle Horizontal | 160° |
| Beam Angle Vertical | 75° |
| Light output ratio | 74% |
| Light flux in lower hemisphere | 86% |
| Directional Intensity Ratio | 3.4 |
|
