Justification for Section 3.3 suggested change: The existing wording requires that the dial be marked in 7 kPa increments and requires that the gage be used to measure pressure at 69 kPa. Thus the user would be required to estimate the width of 1/7 of the space between divisions. Furthermore the accuracy requirement (2kPa) is equal to 1/3.5 divisions. Standard Laboratory Practice only allows for estimating a value equal to the value of each division. In this case one can only estimate to the nearest 3.5 kPa. In addition, after much research, AMEC has been unable to locate a pressure gage that is marked in 7 kPa increments. Available pressure gages are marked in 2 kPa increments. The existing standard does not allow the use of other technology and it is our experience that the use of a pressure transducer and digital display can be checked for accuracy with significantly greater precision without estimating values between marked divisions. Additional Comments A review of older versions of this standard indicates that the initial requirements of the gage (1 psi increments accurate to 0.25 psi) was problematic from the start. Revisions to the standard to include SI units as the standard resulted in even more problems and required the use of equipment that is not readily available.
Keywordsfineness of hydraulic cement; Portland cement; Sieve analysis--building materials; Fineness--hydraulic cement (blended/portland); Hydraulic cement concrete
Draft Under Development