{"data":{"id":"us/40-cfr-1065.315","jurisdiction":"us","citation":"40 CFR 1065.315","heading":"Pressure, temperature, and dewpoint calibration.","body":"(a) Calibrate instruments for measuring pressure, temperature, and dewpoint upon initial installation. Follow the instrument manufacturer's instructions and use good engineering judgment to repeat the calibration, as follows:\n(1) Pressure. We recommend temperature-compensated, digital-pneumatic, or deadweight pressure calibrators, with data-logging capabilities to minimize transcription errors. We recommend using calibration reference quantities that are NIST-traceable within ±0.5% uncertainty.\n(2) Temperature. We recommend digital dry-block or stirred-liquid temperature calibrators, with data logging capabilities to minimize transcription errors. We recommend using calibration reference quantities for absolute temperature that are NIST-traceable within ±0.5% uncertainty. You may perform linearity verification for temperature measurement systems with thermocouples, RTDs, and thermistors by removing the sensor from the system and using a simulator in its place. Use a NIST-traceable simulator that is independently calibrated and, as appropriate, cold-junction compensated. The simulator uncertainty scaled to absolute temperature must be less than 0.5% of Tmax. If you use this option, you must use sensors that the supplier states are accurate to better than 0.5% of Tmax compared with their standard calibration curve.\n(3) Dewpoint. We recommend a minimum of three different temperature-equilibrated and temperature-monitored calibration salt solutions in containers that seal completely around the dewpoint sensor. We recommend using calibration reference quantities for absolute dewpoint temperature that are NIST-traceable within ±0.5% uncertainty.\n(b) You may remove system components for off-site calibration. We recommend specifying calibration reference quantities that are NIST-traceable within ±0.5% uncertainty.","path":["Title 40—Protection of Environment","CHAPTER I—ENVIRONMENTAL PROTECTION AGENCY","SUBCHAPTER U—AIR POLLUTION CONTROLS","PART 1065—ENGINE-TESTING PROCEDURES","Subpart D—Calibrations and Verifications"],"source_url":"https://www.ecfr.gov/api/versioner/v1/full/2026-08-25/title-40.xml","current_through":"2026-08-25","vintage":"","retrieved_at":"2026-08-27T02:26:04Z","sha256":"bc625e8cf20090cbf10586017340a5856b6a509ede6d5f1b043ab0afa7d67100","source_id":"us-cfr","stale":true,"prev":"us/40-cfr-1065.310","next":"us/40-cfr-1065.320"},"notice":"GroundRules: Original legal text. Not legal advice."}