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Keith Blackman Limited full range | Gas Lanterns
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Inverted High Pressure Gas Lamp
High pressure gas lamp. Revolutionary design for high pressure gas systems. Some of the heat
from the hot products of the combustion of the gas was given to the gas-air mixture
by means of a special heat interchanger. (This was a radical departure from the
accepted theory that the burner of a high pressure gas lamp had to be kept as
cool as possible.) Keith showed that the aim must be to heat
the mixture to within a few degrees of its ignition temperature. Intensities of
50-60 candle power in the horizontal plane for each cubic foot of gas burner were
achieved. First exhibited at the Franco-British Exhibition in 1908 and at the
Scottish National Exhibition in Edinburgh in the same year. Designed for use in most of the principle streets
of the City of Westminster in 1911, installed and maintained by the
Gas Light and Coke Company. The lamps
were used with the Keith Rotary Gas Compressor. This design of lamp
is used for large units having two or three mantles each
giving 1,500 candle power nominal. Each mantle has its
separate burner system, so that it is possible to arrange for
cutting out part of the light after midnight. Suitable controlling
means are fitted to the tubular supports or, in some cases, to the
bottom casting embodying the socket and arms.
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???
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3,000-4,500 candle power
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2-3 burners
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Post Top
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1937 Paper
1937 Paper
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Suspension Lamp / Keith Lamp
High pressure gas lamp. Some were fitted with special directional reflectors.
Standard pattern suspension lamp of pleasing design, supplied with a special heat-resisting
globe which alows the use of smaller casings. There are four models with illumination output
of 500, 750, 1000 and 1500 candle power. Each of the lamps, when used for street lighting,
can be supplied with raising, lowering and trversing gear for bracket and central suspension.
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805
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500 candle power
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1 burner
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Top Entry
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1932 catalogue
1944 Journal
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805
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750 candle power
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1 burner
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Top Entry
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1932 catalogue
1944 Journal
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805
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1000 candle power
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1 burner
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Top Entry
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1932 catalogue
1944 Journal
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805
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1500 candle power
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1 burner
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Top Entry
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1932 catalogue
1944 Journal
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Suspension Lamp
High pressure gas lamp. Described as a smaller version of the City lamp. Could be fitted with 1932 pattern heaters
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???
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2000 candle power
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2 burners
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Top Entry
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1932 catalogue
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Suspension Lamp
High pressure gas lamp. Described as using the Standard Pattern. Used in the City of London and West End.
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920
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3000 candle power
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2 burners
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Top Entry
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1932 catalogue
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City Lamp
High pressure gas lamp.
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???
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??? candle power
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2 burners
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Top Entry
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1932 catalogue
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nominal squat pattern lamp / squat type keith lamp
High pressure gas lamp. A range of Squat pattern lanterns were made. Some were fitted with special directional
reflectors. A high pressure gas lamp, fitted with an automatic lighter, and largely employed for
street lighting on raising, lowering and traversing gear. Short overall length, and fitted either
with the standard 22" reflector, or smaller 16" reflector. Could also be used for shop front lighting.
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807
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1000 candle power
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1 burner
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Top Entry
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1932 catalogue
1938 programme
1945 Advert
1945 Programme
1946 Advert
1947 book
1951 book
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supervia
A high pressure gas lamp made under licence from the patentees
South Metropolitan Gas Company. It is also known
as the Metro-Supervia lamp. Specially designed for street lighting.
Large numbers of these are used in London and the provinces
and the lamp is claimed to be the last word in street lighting by gas. Suited for bracket arm or
central suspension. Can be fitted with axial or non-axial reflector. Believed to have been introduced
in 1935. It has an important modification to the shape of the incandescent mantle, with
a special slit burner. The mantle, in shape, is like a flat bag. The flat sides are kept from
blowing out by cross stitches inside the mantle. The flat surfaces of the mantle are arranged
to face up and down the street so that most of the light is given in the direction where
it is needed. With it there is an increase in the flux of light above that obtaiend
with the ordinary cylindrial mantle for a given gas consumption - this is probably
due to an increased pre-heating of the combustible mixture: the mantle is fixed closer
to the underside of the heater, and the mixture in passing through a narrow slit
is more highly heated throughout than is possible in the final stage of heating in
a cylindrical nozzle. Incldues a Holophane refractor giving maximum directional beam
10° below the horizontal. Made in two sizes with enamelled steel reflectors 22" diameter. Length
with cup and ball joint and automatic lighter is 27½". The light can be reduced, say at midnight,
by lowering the gas pressure.
Has a 'Type 1 Distribution' (Non Cut-Off) according to the draft 1945 specification.
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Supervia
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??? candle power
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??? burners
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Top Entry
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1935 Paper
1936 Journal
1937 Advert
1937 Programme
1937 Paper
1939 Journal
1944 Journal
1945 Programme
1945 Paper
1946 Advert
1947 book
1951 book
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standard keith lamp
High pressure gas lamp designed for column fixing. The gas, at 3lbs pressure
from the high-pressure main, enters the lamps by way of a stirrup fitting (A)
which carries a tube (B) which is removable to allow easy withdrawal of
the nipple holder (C) for cleaning, when necessary. The correctly formed
venturi tube (D) enables the jet of gas to entrain all the air required for
the complete combustion of the gas. The pressure of the gas and air mixture at
the end of the venturi is sufficient to overcome the resistance of
the parts of the gasburner system, including the mantle. A screw (E)
adjustable from the outside of the lamp casing, is provided to enable
adjustment of the quality of the mixture to be made, the air-to-gas ratio
being dependent upon the resistance to the flow. This is necessary in order
to attain the best possible lighting effect. It is to be noted that the
injector is capable fo producing a mixture with an excess of air when
the lamp is fully heated and the adjusting screw is open to the full
extent. THis allows the necessary adjustment to be made when the lamp has
reached normal working conditions by screwing (E) inwards. The heater (F)
with its burner nozzle (G), is a most important component in the lamp.
It is designed to allow the gas-air mixture to be heated by the hot gases
leaving the incandescence mantle. This heater, or heat interchanger,
paradoxically as it may seem, serves to keep the burner nozzle cool - or
at least, keeps it from becoming heated to an undesirable temperature. This
is effected by the rapid conduction of heat from the nozzle to the body
of the heater through which the combustible mixture flows on its
way to the burner heat. To aid the conduction of the heat from the
end of the nozzle, the latter is of heavy section and is made of metal
having good heat-conducting properties. The absorption of too much heat
by the metal nozzle is prevented by surrounding it with a close fitting
clay ring (H). To this ring the mantle (J) is attached and
the clay ring is screwed on to the nozzle flame-tight. The nozzle is
always the hottest portion of the burner, but with the arrangement
described its temperature is kept below the ignition temperature of
the combustible mixture, and provided this temperature is not
exceeded, the hotter the nozzle the greater will be the light from the
mantle. So that it may burn quietly, it is important to remove turbulence in the air-gas
mixture before it issues from the nozzle. Eddying also increases the
tendency for the flame to "strike back" into the heater. The heater (F) is formed
of two dished cast-iron plates between which is clamped a metal diaphragm which is
provided with a number of small holes neare its periphery. When the mixture issues
from the older end of the venturi tube there is considerable turbulence, but in
its passage over the diaphragm and through the small holes this is damped down.
Any remaining turbulence is removed by means of a metal gauze (K) in the nozzle
itself. This gauze also serves to prevent flash back of the flame on extinction,
which might damage the mantle. It has already been noted that for the development of
the maximum light the ideal mixture is one in which the correct amount of air is
mixed with the gas for its complete combustion, and with such a mixture the speed
of propagation of the flame through it is also at its maximum. Therefore, the special
precuations indicated must be taken to prevent the flame striking back. The mantle,
which is tied to the clay ring, is not incinerated until it has been screwed onto the
metal nozzle. When first "burnt off" the fabric is in its most fragile condition, and it
is, therefore, desirable to light the burner with a deficiency of air in the mixture,
which gives gentle ignition. To avoid upsetting the quality of the combustible mixture
by operating the adjusting screw, when re-mantling is necessary, a metal disc (L),
attached to the end of a bi-metal strip, is provided in the upper half of the heater.
When the lamp is cold this disc offers resistance to the flow of air; but when the
heater is warmed the strip carrying the disc bends back and allows the proper quantity
of air to flow with the gas. The time taken for this operation is only a few
minutes. The lamp casing consists of an inner cylindrical body (M) fitted with a
transverse box (N), and made usually of stainless steel. This material has been
found to be the best for withstanding the high temperature and the corrision due to
condensation in the first minutes of lighting. The transverse box is connected
with the air inlet chamber (O) of the lamp and closed off otherwise from
the chimney, so that the injector which it surrounds can only draw fresh air
warmed up by the products of combustion which pass up the spaces between the
box and the cylindrical body.
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???
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1000 candle power
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1 burner
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Top Entry
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1937 Paper
1945 Advert
1945 Programme
1946 Advert
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keith column lamp
High pressure gas lamp. Column version of the Standard Keith Lamp (above).
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???
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??? candle power
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1 burner
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Post Top
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1937 Paper
1945 Advert
1946 Advert
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Nominal Suspension Lamp / Keith Suspension Lamp
For use on high-pressure gas. Used for both street lighting and shop lighting. The lamp is complete with automatic lighter for distance lighting,
and has a chromium-plated copper casing and dome, black enamel cowl and reflector, and forms a
handsome unit. It is of multiple burner type, giving an output of 1000 candle power. The model can
also be supplied with a single burner.
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808
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??? candle power
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1 burner
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Top Entry
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1938 programme
1944 Journal
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808
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1000 candle power
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3 burners
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Top Entry
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1938 programme
1944 Journal
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Magnalux / High Intensity Lamp / High Candlepower Low Pressure Lamp
Described as a "distinct innovation" in 1937. Based on ideas first put forward
by Lucas. This operates on low-pressure gas mains
and embodies novel principles to ensure much higher candle-power results than obtainable from
ordinary low-pressure lamps. Introduced as the Magnalux in 1938, it offered 50% gerater efficiency
than low-pressure lamps, with results approaching the performance of high-pressure gas. Fig. 11 is a diagram
showing the principle of the new lamp: (A) is a mantle, or one of a row
of mantles; (B) is a bunch of small tubes surrounded by a refractory mantle ring
which fits closely to the heater body (C). The tubes (B) are fed
with a mixture of gas and air having as high a proportion of oxygen
as can be obtained by means of the low-pressure gas injector which
feeds the chamber (D). The two chambers (EE) are connected to the
space around and between the small tubes of the bunch (B). The
crux of the problem is to cause the secondary air to enter this space
against the resistance of the mantle and without the pull of the chimney.
Surrounding the chimney body of the lamp is an outer chamber (F)
similar to that used with an ordinary low-pressure lamp, which is supplied
with air through baffled openings above the reflector. This chamber
is not connected directly with the globe (G), so that no secondary
air is allowed to enter the gloe, contrary to the practice in normal
low-pressure lamps. THe chamber communicates at the top with the
chimney by means of the openings (HH), so that the static pressure
in the cmaber is approximately the same as that in the chimney. Two
uprising tubes (JJ) are connected to the chamber (F) by the bends
(KK). These tubes, which have internal spiral strips to facilitate heat
transmission, rise through the chimney and are carried through the
cowl and upwards for an appreciable distance. Return bends on the top
are connected to two descending tubes (LL), the lower parts of which enter, by
bends and horizontal tubes, the chambers (EE). These tubular systems
form syphons which oeprate by the fact that the air in the rising members
is heated by the chimney gases and in the descending members is cooled
by exposure to the outside air. In this way a slight pressure above
atmosphere is set up at the foot of the descending tube. By this means
a supply of secondary air reaches the burning mixture, which issues
from the tubes (B), in quantity slightly in excess of that required
for complete combustion, and at a sufficient pressure to overcome
the mantle resistance. The important point to note is that no
matter how the suction of the main chimney is increased or reduced
by the wind, it can have no influence on the pressure difference
set up by the syphons. Fig 12 is the section at right angles
and shows a row of mantles intended to be disposed broadside
to the length of the street: Injector (M) provides the primary
mixture. The gas supply is brought down the centre
of the lamp in the usual way and passes through a
special form of auto-lighter (N) to the gas nipple.
Adjustment of the quality of the mixture is made
by the needle valve (O). On the other side a box
(P) contains a Horstmann electric
lighter of the Comet type and its battery.
Fig 13 shows a modified prototype. The chimney is divided, which enables
the mantles to be rasied nearer to the suspension point, so that this
distance is no greater than in standard low-pressure lamps. The syphon
tubes are arranged to straddle the bracket or other means of suspension.
Both prototypes were shown at the 1937 Folkestone Conference with
the lamp of Fig. 11 installed in Marine Terrace and Lower sandgate Road
and the lamp of Fig. 13 was installed in Padnor Park Road.
Initially avaialble in three- and four-light options. A lumen output of 15,000
is obtained from the four-light size on gas supplied at a pressure of 5" w.g. THis
increase in efficiency is of the order of 50% over that hitherto obtainable
with low pressure outdoor lamps.
First installed along Woburn Place in Holborn in 1938.
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"Small" High Intensity Lamp
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??? candle power
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1, 3, 4 burners
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Top Entry
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1937 Programme
1937 Paper
1937 Journal
1938 Journal
1938 Advert
1938 Programme
1939 Advert
1939 Journal
1939 Programme
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"Small" High Intensity Lamp
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??? candle power
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3 burners
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Top Entry
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1937 Programme
1937 Journal
1938 Advert
1938 Programme
1939 Advert
1939 Journal
1939 Programme
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"Large" High Intensity Lamp
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??? candle power
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4 burners
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Top Entry
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1937 Programme
1937 Journal
1938 Advert
1938 Programme
1939 Advert
1939 Journal
1939 Programme
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Decorative Lamp
High pressure gas lamp principally for shop facia lighting.
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???
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1000 candle power
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1 burner
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Top Entry
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1945 Programme
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