ANSI IESNA RP 27.2-2000 pdf download Recommended Practice for Photobiological Safety forLamps & I amp Systems- Measurement Techniques .
4.1 Lamp Seasoning To maintain stable output during the measurement process and provide reproducible results, lamps shall be seasoned for an appropriate period of time. During the initial period of operation a lamp will change as its components come to equilibrium. If measurements are taken of an unseasoned lamp, the variations within the measurement period and between measurements will be significant. As the output of a lamp generally decreases over life, the seasoning time should be short to result in conservative hazard evaluations. Seasoning of lamps shall be done as stated in IESNA LM-54. For the purposes of these standards, the lamp output at the end of the seasoning period is the initial output. For lamps not covered by the LM-54 standard, a study may be required to find the minimum time required to stabilize the operation of a source.
4.2 Test Environment Measurements shall be made in a controlled environ- ment. The operation of sources and measurement equipment is impacted by environmental factors. Additionally, the formation of ozone in the measurement path may compromise accuracy and may pre- sent a safety hazard.
4.3 Temperature The ambient temperature will significantly influence the output of certain light sources; e.g., fluorescent lamps. The ambient temperature in which measurements are taken shall be maintained in accordance with the appropriate IESNA LMs noted in Section 3.1.
4.4 Drafts The characteristics of some light sources are signifi- cantly affected by drafts. For the applicable light source, refer to the appropriate IESNA LM guides noted in Section 3.1. Other than normal convection air, air movement over the surface of test lamps should be reduced as much as possible consistent with safety considerations (ozone production). When the system under test provides interlocks that maintain circulation, measurements shall be performed with circulation.
4.5 Extraneous Radiation Careful checks should be made to ensure that extra- neous sources of radiation and reflections do not add significantly to the measurement results. Visually black surfaces can be highly reflective to UV and IR radiation.
Radiation from hot baffles must be considered in infrared measurements due to the large input angle subtended by baffles. Water cooled baffles and double baffles are two methods for addressing baffle heating.
4.6 Lamp and Lamp System Operation The lamp or lamp system shall be operated under conditions that are standardized.