CFR > Title 40 - Protection of Environment > CHAPTER I—ENVIRONMENTAL PROTECTION AGENCY > SUBCHAPTER C—AIR PROGRAMS (Parts 50–99) > PART 89—CONTROL OF EMISSIONS FROM NEW AND IN-USE NONROAD COMPRESSION-IGNITION ENGINES > SUBPART D—Emission Test Equipment Provisions (§89.301 to §89.331) > 89.326—Engine intake air humidity measurement.

89.326—Engine intake air humidity measurement.

(a) Humidity conditioned air supply. Air that has had its absolute humidity altered is considered humidity- conditioned air. For this type of intake air supply, the humidity measurements must be made within the intake air supply system and after the humidity conditioning has taken place.
(b) Nonconditioned air supply procedure. Humidity measurements in nonconditioned intake air supply systems must be made in the intake air stream entering the supply system. Alternatively, the humidity measurements can be measured within the intake air supply stream.

Code of Federal Regulations

[59 FR 31335, June 17, 1994. Redesignated at 63 FR 56995, Oct. 23, 1998]