MELZ Medium Pressure Mercury ИГАР-2 500W

Medium pressure mercury lamps having hardglass arc tubes were produced in the former Soviet Union by the Moscow Electric Lamp Plant (MELZ). They were classified as ИГАР (Интенсивная Газосветиая Аргоиио-Ртутная), in English IGAR (Intensive Gas-discharge lamp with Argon & Mercury). The largest model was this ИГАР-2 of 500W, joined by the smaller ИГАР-3 400W and ИГАР-4 250W ratings. There was also an earlier ИГАР-1 500W actinic lamp with bare arctube.

The Soviet design has a number of differences vs Western lamps. Most notable is the unusually low luminous efficacy - this 500W rating delivering fewer lumens than the foreign 400W types. It is suspected that the reason may be due to a difference in the type of glass used for the arc tube. Foreign lamps employ high softening temperature aluminosilicate glasses, and over the years the glass was made progessively harder which permitted hotter operation - the resulting increase in mercury vapour pressure leading to increased efficacy. This Russian lamp is characterised by an unusually long discharge tube and quite low power density, which may have been required if it is made from a lower softening temperature glass, such as ordinary borosilicate.

The electrodes take the form of open coiled-coils, coated with an emissive oxide. The feedthroughs are unusually sleeved in small glass tubes. The emitter material appears to be different than on Western lamps. During run-up it is normal for tiny particles of emitter to become dislodged, and if these fall into the arc they become ionised. Most MA lamps show a pinkish colour flare when this happens, but this Soviet lamp produces an unusual deep violet colour flash, as illustrated in the third illuminated photograph.
Manufacturer: МЭЛЗ (MELZ Moscow Electric Lamp Plant)
Lamp Power: 500 Watts
Lamp Current: 4.4 Amps
Lamp Voltage: 125 Volts
Cap Type: E40s/45 Galvanised Steel + Vitrite
Bulb Type: T-41 T-13 in eighths/inch
Bulb Finish: Clear Borosilicate hard glass
Electrodes: CC-8 Open Coil Emissive oxide coating
Arc Length: 178 mm 7.0 inches
Atmosphere: Inner: Hg | Ar (1 atm) Outer: Nitrogen
Luminous Flux: 16,000 lm @ 100 hrs
Luminous Efficacy: 32.0 lm/W @ 100 hrs
Colour Temperature & CRI: CCT: 5400K CRI: Ra 6
Chromaticity Co-ordinates: CCx: 0.337 CCy: 0.421
Lifetime: 5000 hours
Warm-up & Re-strike Time: 6 minutes 10 minutes
Burning Position: Vertical ± 10°
Overall Length: 352 mm 13⅞ inches
Light Centre Length: 198 mm 7¾ inches
Factory: Moscow USSR
Date of Manufacture: February 1957 Date Code II-57
Original Value: Unknown
References: 1) Instruction Leaflet 1 supplied with lamp
2) Instruction Leaflet 2 supplied with lamp
3) Elektrische Lichtquellen Gasentladungslampen, A.P. Iwanov, publ. Akademie-Verlag Berlin, 1955, pp. 371-373, 394-397
4) ИГАР-2 Lamp of Roman Kalimulin at IXBT Russia
5) ИГАР-2 Lamp of Andrey Vasilievich at IXBT Russia
6) Лампьі Типа ИГАР и их Применение в Светокопировальньіх Аппаратах, Р.Т. Извеков & проф. А.П. Ивановым, Московский электротехнический комбинат „Электрозавод“, 1935 (IGAR Type Lamps and their Application in Photocopy Apparatus, R.T. Izekov & Prof. A.P. Ivanov, Moscow Electrotechnical Plant 'Electrozavod', 1935)