The purpose of this contract is for the preventative maintenance and ISO/IEC 17025 accredited calibration of four environmental chambers located on the NIOSH Pittsburgh campus. The equipment requires ... The purpose of this contract is for the preventative maintenance and ISO/IEC 17025 accredited calibration of four environmental chambers located on the NIOSH Pittsburgh campus. The equipment requires basic maintenance and regular calibration in order to maintain ISO/IEC 17025 accreditation and to be able to accurately conduct respirator approval and audit testing..