The ASTM D6536/D6536M-18 standard provides a method of measurement of the length of the dip tube of a mechanical pump dispenser. This method is used to determine the length from the bottom of the sealing surface of the pump dispenser to the end of the dip tube, ensuring accurate measurement of the bare length of the dip tube. This is essential to ensure that the pump dispenser works effectively in different containers. The unit of length used in the standard can be SI units or inch-pound units, and the values in each system need to be applied independently. The standard does not cover all safety issues. Users need to follow the corresponding safety and environment specifications, and determine the applicability of the regulations according to the actual situation.