The scope of this standard is to describe various instruments and techniques for the measurement of moist air properties. Attention is given to methods appropriate for use in ASHRAE standard methods of test for rating or for determining compliance with ASHRAE environmental standards. These descriptions include the range of conditions over which their use is practicable@ the associated attainable accuracy@ and proper techniques of use to achieve desired accuracy. Specific attention is given to the wet-bulb and dry-bulb psychrometer and the dew-point hygrometer@ while other methods also are discussed. A discussion also is presented concerning calibration@ reference standards@ and traceability to standards of the National Institute of Standards and Technology (NIST) to help ensure accurate measurements. PURPOSE This standard sets forth recommended practices and procedures for the measurement and calculation of moist air properties in order to promote accurate measurement methods for specific use in the preparation of other ASHRAE standards. This standard recommends procedures for measurement of moist air properties in connection with a. the establishment of the desired moist air environment for tests of heating@ refrigerating@ humidifying@ dehumidifying@ and other air-conditioning equipment and b. the determination of the quantity of moisture in airstreams moving through or within such equipment or spaces.