Hefner lamp

The Hefner candle ( HK) is an obsolete, in Austria, Germany and Scandinavia once common unit of luminous intensity.

Definition

It is defined by the amount of light that radiates a designed by the physicist Friedrich von Hefner - Alteneck Amylacetatlampe, the Hefner lamp at 40 mm flame height and 8 mm wick diameter in the horizontal direction.

History

The light unit was adopted in 1890 by the German Association for Gas and Water professionals as Hefner unit and 1897 and by the Association of German Electrical Engineers under the name Hefner candle.

So far in Germany available light units the old light unit were ( defined by a 83 g heavy wax candle that burns with a flame height of 42 mm), the unit of the German Association of Gas and Water, DVGW ( defined by a paraffin wax candle 20 mm in diameter at 50 mm flame height ) and the Berlin light unit ( defined by a spermaceti candle with flame height 44.5 mm and a consumption of 7.77 g per hour). Subsequent units of intensity are the New Candle ( NK) from 1 July 1942 and the candela (cd ) from 1948.

The unit HK is still used today in the name of gas and kerosene pressure lamps.

Conversion

1 HK