---
kind: "section"
citation: "40 C.F.R. § 1065.315"
title: "40"
number: "1065.315"
heading: "Pressure, temperature, and dewpoint calibration."
url: "https://uscodex.org/cfr/40/1065.315"
---

# §1065.315. Pressure, temperature, and dewpoint calibration.

- (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:
  - (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.
  - (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.
  - (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.
- (b) You may remove system components for off-site calibration. We recommend specifying calibration reference quantities that are NIST-traceable within ±0.5% uncertainty.

## Notes

### Amendments

[70 FR 40516, July 13, 2005, as amended at 73 FR 37305, June 30, 2008; 75 FR 23040, Apr. 30, 2010; 79 FR 23768, Apr. 28, 2014; 88 FR 4674, Jan. 24, 2023; 89 FR 29797, Apr. 22, 2024]

### Authority

Authority: 42 U.S.C. 7401-7671q.

### Source

Source: 70 FR 40516, July 13, 2005, unless otherwise noted.

### Amendments

[70 FR 40516, July 13, 2005, as amended at 73 FR 37305, June 30, 2008; 75 FR 23040, Apr. 30, 2010; 79 FR 23768, Apr. 28, 2014; 88 FR 4674, Jan. 24, 2023; 89 FR 29797, Apr. 22, 2024]