This paper describes the National Voluntary Laboratory Accreditation Pro gram (NVLAP), administered by the National Bureau of Standards, and sum marizes the proficiency testing program for the Thermal Insulation Materials Laboratory Accreditation Program (Insulation LAP). NVLAP and its procedures for assessing, evaluating, and accrediting laboratories are presented briefly. The scope of the Insulation LAP is described. The results of the proficiency testing program over a four year period of testing are given. Eight tables show the sta tistical results of data submitted by participating laboratories for thermal trans mission properties, thermal conductance, surface flammability, settled density, critical radiant flux, and smoldering combustion.

Data System and a system of information analysis centers dealing with the broader aspects of the National Measurement System; provides appropriate services to ensure that the NBS staff has optimum accessibility to the scientific

Pressure bottle method of decomposition and analysis ior explosive or volatile compounds capaljle of decomposition at temperatures below the boiling-point. (3) Elaboration of methods for simultaneous recognition of hypophosphorous, phosphorous and phosphoric acids. (4) Discussion of the source of hydrogen in the preparation of phosphine. (5) Qualitative test for phosphine by ammonium molybdate.

The term NVLAP and the NVLAP logo are registered marks of the Federal Government, which retains exclusive rights to control the use thereof. Permission to use the term and symbol (NVLAP logo with approved caption) is granted to NVLAP-accredited laboratories for the limited purpose of announcing their accredited status, and for use on reports that describe only testing and calibration within the scope of accreditation. NVLAP reserves the right to control the quality of the use of the NVLAP term, logo, and symbol. • Annex A (normative) and Annex B (informative) have been added. This handbook is also available on the NVLAP web site (http://www.nist.gov/nvlap).

Portable X-ray fluorescent lead analyzers offer the most cost-effective and adaptable means for the non-destructive detection and measurement of lead in paint in housing. However, commercially available portable lead analyzers have had poor accuracy and precision below lead levels of about 3.0 milligrams of lead per square centimeter of surface area. This is particularly serious because the current operational criteria for lead paint hazard abatement, 1.5 or 2.0 mg lead/cmm aximum (used in many communities), is in this range. They have also performed relatively unsatisfactorily with regard to serviceability and maintenance.Two new portable lead analyzers based on x-ray fluorescence developed elsewhere under HUD contracts have been evaluated.One of the new devices was found to be unacceptable for field use because the prototypes of it were all inaccurate and imprecise, difficult to use and maintain.They were also very bulky and heavy.Although prototypes of the other lead analyzer did not meet all the requirements of the HUD contract, they showed considerable improvement over all previously available instruments in terms of accuracy, precision, ease of operation, and portability. They did, however, have some deficiencies which are discussed in the report.