Use
Designed for use in Groups A1 and A2 at mounting heights of up to 35ft. and in Group A3 at mounting heights of up to 40ft.

Lamp
175-watt Osram Golden Linear Sodium lamp.

Mounting
The Z9517 side entry lantern requires not less than 5 in. of horizontal unthreaded 1¼ in. B.S.P. When fully home two 3/8" diameter Allen type grub screws grip the barrel. Water running along the barrel is prevented from entering the lantern by a water baffle.

Lantern Body
One-piece light alloy die-casting. The body carries a white enamelled over-reflector, lampholders, lampholder clips and porcelain terminal block. An earthing screw and porcelain cable cleat are provided.

Lampholders
Two ceramic insultated bi-pin holders.

Optical System
Light Control is provided by two 'Perspex' refractor plates. The prismatic sides of the plates are bonded one to each inner side of a 'Perspex' bowl. Both inner and outer surfaces of the bowl are smooth for easy cleaning. The ends and sides of the bowl are lightly obscured.

The bowl is hinged to the lantern body and fastened by means of two stainless steel catches. A tropicalised felt gasket between the body casting and bowl ensures a weatherproof seal when the lantern is closed.

Weathering Finish
The alloy used is specially selected for its resistance to corrosion. Further protection is obtained by the use of a pre-treatment primer and stove enamel top coat.

[1] Principle conical polar curve.
[2] Principle vertical polar curve and polar curve in vertical plane parallel to street axis.

The above iso-candela diagram is based on an average lamp light output through life from a 175-watt Osram Golden Linear Sodium Lamp (20,000 lumens average, applicable at time of print).

Photometric data obtained from a Z9517 lantern with 175W Osram Linear Sodium Lamp	Lantern Data	Requirements of B.S. 1788 & C.P. 1004
Light flux in lower hemisphere (lumens)	13,200	See CP1004 Tables 10-16
Downward light output ratio	0.66	No limits specified
Angle of elevation of upper limit of beam	79°	75° must be within beam
Angle of elevation of lower limit of beam	67°	75° must be within beam
Peak intensity ratio	2.13	1.8 to 4.0
Maximum intensity ratio in the zone from 0° to 30°	1.18	0.3 to 1.7
Minimum intensity ratio in the zone from 0° to 30°	1.04	0.3 to 1.7
Maximum intensity ratio in the zone from 0° to 30°/Peak intensity ratio	0.55	0.7 Maximum
Angle at which 1.2 intensity ratio occurs above peak	83°	80° to 86°
Intensity ratio at the horizontal	0.38	0.7 maxiumum
Divergence of beam centre from the axis of the road in azimuth	Zero	15° Maximum

The Z9517 side entry lantern with the bowl opened to show the lamp mounting

Sectional scale drawing of Z9517 lantern. Lantern weight: 12½ lbs. (5.7 Kg)