NTP (Normal Temperature & Pressure) Definitions
A few questions have arisen regarding the term NTP (Normal Temperature and Pressure). The following table helps to sort any potential confusion.
| Agency | Pressure | Temperature |
| Traditional
(Chemistry/Physics) |
29.92 “Hg
760 mm Hg |
492 ˚R
273 ˚K |
| ACGIH
(TLV) |
29.92 “Hg
760 mm Hg |
530 ˚R
298 ˚K |
| NIOSH/AIHA
(Traditional) |
29.92 “Hg
760 mm Hg |
537 ˚R
298 ˚K |
| ASHRAE
(Ventilation) |
29.92 “Hg
760 mm Hg |
528 ˚R
293 ˚K |
Source: Useful Equations, Practical Applications of OH&S Match: D. Jeff Burton, PE, CIH