Standard lamps

The smoke point corresponds to the maximum possible flame height (without smoke formation) from a standardized lamp (NF M 07-028). The values commonly obtained are between 10 and 40 mm and the specifications for TRO fix a minimum threshold of 25 mm. The smoke point is directly linked to the chemical structure of the fuel it is high, therefore satisfactory, for the linear paraffins, lower for branched paraffins and much lower still for naphthenes and aromatics. 

The luminometer index (ASTM D 1740) is a characteristic that is becoming less frequently used. It is determined using the standard lamp mentioned above, except that the lamp is equipped with thermocouples allowing measurement of temperatures corresponding to different flame heights, and a photo-electric cell to evaluate the luminosity. The jet fuel under test is compared to two pure hydrocarbons tetraline and iso-octane to which are attributed the indices 0 and 100, respectively. The values often observed in commercial products usually vary between 40 and 70 the official specification is around 45 for TRO. 

Johnson et al. (1962) measured the quantum yield of Cypridina luciferin in the luciferase-catalyzed reaction for the first time, using a photomultiplier calibrated with two kinds of standard lamps. The measurement gave a value of 0.28 0.04 at 4°C in 50 mM sodium phosphate buffer, pH 6.5, containing 0.3 M NaCl. The quantum yield... 

Sample cells were fabricated from tungsten. Additional crucibles composed of a Pt-40 w/o Rh-8 w/o W alloy were also used in experiments on the PuPt phase. Each tungsten cell was vacuum outgassed at 1800 for 1 h before an experiment. The cell temperature was determined during the measurements by sighting with a pyrometer (Pyrometer Instrument Co.) onto a blackbody hole in each cell base. The pyrometer and sight glasses were calibrated with an NBS standard lamp. 

Calibration. In general, standards used for instrument calibration are physical devices (standard lamps, flow meters, etc.) or pure chemical compounds in solution (solid or liquid), although some combined forms could be used (e.g., Tb + Eu in glass for wavelength calibration). Calibrated lnstr iment parameters include wavelength accuracy, detection-system spectral responsivity (to determine corrected excitation and emission spectra), and stability, among others. Fluorescence data such as corrected excitation and emission spectra, quantum yields, decay times, and polarization that are to be compared among laboratories are dependent on these calibrations. The Instrument and fluorescence parameters and various standards, reviewed recently (1,2,11), are discussed briefly below. 

Once we have done this, we now have our three primary colors in the form of standard lamps, and can proceed to determine Items 1,2 3, given above on page 421. To do this, we vary the wavelength of the monochromatic light, and determine relative amounts of red, green and blue light required to match the monochromatic color. This is done, as stated before, for about 5000 observers. 

For recording of the emission spectrum, the emitted radiation is focussed on the slit of a monochromator and intensities measured attach wavelength. Since sensitivities of photocells or photomultipliers are wavelength dependent, a standardization of the detector-monochromator combination is necessary for obtaining true emission spectrum This can be done by using a standard lamp of known colour temperature whose emission characteristics is obtained from Planck s radiation law. The correction term is applied to the instrumental readings at each wavelength. Very often substances whose emission spectra have been accurately determined in the units of relative quanta per unit wavenumber intervals are... 

Lamp burning a test of burning oils in which the oil is burned in a standard lamp under specified conditions in order to observe the steadiness of the flame, the degree of encrustation of the wick, and the rate of consumption of the kerosene. 

According to Malyj and Griffiths (1983), determining the equilibrium rotational or vibrational temperature by the Stokes/anti-Stokes ratio is not as simple and straightforward as the equations imply. The authors discuss the problems which evolve as a result of using standard lamps and show how to meet these difficulties by using reference materials to measure the temperature as well as to determine the instrumental spectral response function. The list of suitable materials includes vitreous silica and liquid cyclohexane, which are easy to handle and available in most laboratories. The publication includes a detailed statistical analysis of systematic errors and also describes tests with a number of transparent materials. 

It is important to differentiate between calibration of the UV filter radiometer or luxmeter as prescribed in the ICH guideline and calibration of these devices for a specific lamp. In the first case, the calibration is carried out by the manufacturer to establish the response curve of the device. If the meters are calibrated against a standard lamp and used as received, they are well suited for measuring any variation of irradiance across the sample area and changes in total output with time. But they cannot be used to give an absolute measurement of irradiance or to compare irradiance between sources unless they are calibrated specifically for each source (21). 

Figure 15. Variation of relative emission with wavelength for Hanovia ozone-free and standard lamps (56)...

An optical pyrometer is simply a photometer using monochromatic light (usually. red) in which the intensity of radiation from either a standard or a constant source (electric lamp, oil flame, etc.) is compared with that from the object of which the temperature is desired. Frequently the two intensities are made equal by adjusting various types of absorbing devices (absorption glasses, iris diaphragm, etc.) interposed either on the furnace side or the standard-lamp side of the pyrometer, depending upon... 

TABLE 7.1. Standard Lamp Types, Lamp Efficacy, and Typical Applications"... 

The 24-h burning test (ASTM D-187) involves noting the average oil consumption, change in flame dimensions, and final appearance of wick and chimney. No quantitative determination of char value is made (IP-10). In this method the oil is burned for 24 h in the standard lamp with a flame initially adjusted to specified dimensions. The details of operation are carefully spec-... 

Figure 5.15 Calibration scheme — calibration standard lamp.

Reliability of Radiation Thermometers. Calibration of radiation thermometers at NIST is accomplished by focusing the radiance sensor at a blackbody furnace with known temperature. This blackbody furnace is previously calibrated by comparison calibration against a standard lamp, which, in turn, is calibrated at the gold point [52], With calibration performed at NIST, the accuracy of a radiation thermometer is within 0.4°C at the gold point, within about 2°C at 2200°C and about 10°C at 4000°C. 

Other Radiation Thermometers Traditionally, radiation thermometers used a red filter to achieve a monochromatic comparison between the incoming radiation and that of a standard lamp. With the development of photomultipliers, better precision and automation are possible, including direct detection—eliminating the use of a standard lamp in actual applications. 

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