National Physical Laboratory

Calibration and supply of pyrometric lamps (700 °C to 2600 °C)

Pyrometric Lamp
Calibration of tungsten ribbon lamps

Tungsten ribbon and blackbody lamps are standard sources of thermal radiation whose radiance temperature is accurately related to the lamp current. They provide convenient and portable reference sources for the calibration of other lamps, blackbody sources and some radiation thermometers, such as disappearing filament pyrometers.

NPL can supply calibrated pyrometric lamps operating over the range 700 °C to 2600 °C with calibration uncertainties as low as 0.5 °C for a high-stability lamp at 1000 °C. NPL also calibrates customer supplied lamps over the range 700 °C to 2600 °C, and disappearing filament pyrometers, against either an NPL standard lamp or a blackbody source, within the range 800 °C to 3000 °C. All calibrations are traceable to the ITS-90, and the service is UKAS accredited (NPL is a UKAS accredited calibration laboratory number 0478).

Technical information

Several different types of calibrated tungsten ribbon and blackbody lamp are available, the choice of which depends on the required accuracy and temperature range - see table below for details. High-stability tungsten ribbon lamps offer the lowest uncertainties, while cylindrical envelope lamps provide a cost effective solution when higher uncertainties can be tolerated. Blackbody lamps have a higher emissivity (0.99) and therefore can be used over a wider wavelength range. However their smaller target size and greater sensitivity to alignment make them more difficult to use than tungsten ribbon types in many situations.

Customers' lamps can be calibrated over the same temperature ranges and with the same calibration uncertainties as equivalent NPL supplied lamps. In order to maintain calibration accuracy it is recommended that all lamps are re-calibrated every two years (every five years for cylindrical envelope types) or after 100 hours of use.

Lamps are normally calibrated at a wavelength in the region of 650 to 660 nm, although calibrations may be carried out at 906 nm by arrangement.

Lamp Type Target sizes
(nominal)
Operational
range / °C
Uncertainty of
calibration / °C
High-stability vacuum 1.5 mm or 3 mm wide 700 to 1700
or
1000 to 1700
±1.0 at 700 °C
±0.5 at 1000 °C
±1.0 at 1700 °C
High-stability gas-filled 1.5 mm or 3 mm wide 1600 to 2200 ±1.5 at 1600 °C
±2.0 at 2200 °C
Blackbody vacuum 1 mm diameter 750 to 1700
or
1000 to 1700
±2.0 at 750 °C
±1.5 at 1000 °C
±2.5 at 1700 °C
Cylindrical envelope
and Single Window
Vacuum
1.3 mm or 2.5 mm wide 700 to 1500 ±3.0 at 700 °C
±1.5 at 1000 °C
±2.5 at 1500 °C
Cylindrical envelope
and Single Window
Gas-filled
1.3 mm or 2.5 mm wide 1300 to 2300 ±4.5 at 1300 °C
±4.0 at 2300 °C
Cylindrical envelope
Double window
Vacuum
1.3 mm or 2.5 mm wide 700 to 1500 ±3.0 at 700 °C
±1.5 at 1000 °C
±2.5 at 1500 °C
Cylindrical envelope
Double window
Gas-filled
1.3 mm or 2.5 mm wide 1300 to 2300 ±3.5 at 1300 °C
±3.0 at 2300 °C
Blackbody gas-filled 1 mm diameter 1600 to 2600 ±5.0 at 1600 °C
±5.5 at 2600 °C

Contact

Customer Services tel: +44 20 8943 6315
E-mail: temperature_enquiries@npl.co.uk

Last Updated: 1 Sep 2017
Created: 11 Sep 2007

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