First Name | Lance |
---|---|
Last Name | Wallace |
Email Address | lwallace73@comcast.net |
Affiliation | |
Subject | Comment on ANSI 867 test method |
Comment | I would like to comment on Section 37.4 of the revised ANSI Standard 867 for testing air cleaners. This section allows monitoring for 8 hours instead of 24 hours if a steady state has been reached. "Steady state" is defined as one in which the slope between hours 7 and 8 is not positive. This definition is defective. Let us assume that a true steady-state has been achieved. Then half of the measured slopes will show a small positive value and half will show a small negative value. According to the defective definition, half of all cases that indeed achieved a steady state after 7 hours would be wastefully required to complete 24 hours of testing. The economic impact of this depends on the fraction of cases that do reach a steady state in 7-8 hours, and on the difference in cost involved in monitoring for 24 hours instead of 8. The definition of the steady state should allow de minimus positive slopes to be proof of a steady state. The value of this positive cutoff can be determined as a function of the allowed precision of the measurement method (2%) coupled with observations of the slopes obtained by a sufficient number of Monte Carlo runs of 60 1-minute averages on a constant concentration subject to random 2% errors. I am aware that the ARB can not themselves change the ANSI Standard but in view of the possible economic consequences of the ARB regulation based on this standard, perhaps the Board can bring this to the attention of ANSI. |
Attachment | |
Original File Name | |
Date and Time Comment Was Submitted | 2008-07-01 08:09:04 |
If you have any questions or comments please contact Clerk of the Board at (916) 322-5594.