WAC 296-835-11035
WAC 296-835-11035. Prepare dip tanks before cleaning
(1) You must drain the contents of the tank and open any cleanout doors.
(2) You must ventilate the tank to clear any accumulated hazardous vapors.
Reference: There may be requirements that apply before an employee enters a dip tank. See chapter 296-809 WAC, Confined spaces.