1.1 These methods cover the measurement of atmospheric pressure with two types of barometers: the Fortin-type mercurial barometer and the aneroid barometer.
1.2 In the absence of abnormal perturbations, atmospheric pressure measured by these methods at a point is valid everywhere within a horizontal distance of 100 m and a vertical distance of 0.5 m of the point.
1.3 Atmospheric pressure decreases with increasing height and varies with horizontal distance by 1 Pa/100 m or less except in the event of catastrophic phenomena (for example, tornadoes). Therefore, extension of a known barometric pressure to another site beyond the spatial limits stated in can be accomplished by correction for height difference if the following criteria are met:
1.3.1 The new site is within 2000 m laterally and 500 m vertically.
1.3.2 The change of pressure during the previous 10 min has been less than 20 Pa.
The pressure, P
1.4 Atmospheric pressure varies with time. These methods provide instantaneous values only.
1.5 The values stated in SI units are to be regarded as the standard.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific safety precautionary statements are given in Section 7.
Product Details
- Published:
- 10/01/2007
- Number of Pages:
- 5
- File Size:
- 1 file , 86 KB