We have recently discovered that there is an inaccuracy in the environmental test conditions contained in the 2A test procedure.The temperature condition called ‘desert (Dry)’ of 60C and 30% RH is really not desert, nor is it particularly dry. In fact, these conditions have almost the same moisture content (absolute humidity) for the environmental conditions of 38C and 85% RH, which is defined as ‘Tropical Wet’.

An internet tool is available to calculate the comparable RH values for a desired temperature when the ‘ambient’ conditions are known. See Psychrometric Calculator.

So, in order for the desert conditions to be dry the absolute humidity should be about 20%. The conditions published in the ASTM D 4332 standard that describe ‘desert’ conditions are 60C and 15% RH. It can be seen from the worksheet that the absolute humidity (AH) is considerably less (19.5%) than it is at 38C and 85% RH (39.3% AH).

I will be working with ISTA to make a revision in the 2A standard to correct this inaccuracy.

Created on Tuesday, May 15th, 2007 at 2:22 pm. | Fled under DDL, Industry Insights. | Comment Feed