(a) A county or municipality may not enact or enforce an ordinance or rule that is inconsistent with this chapter or the board’s rules unless allowed by this chapter.
(b) If a municipality by ordinance adopted rules relating to mobile service units not later than 180 days after the board adopted rules relating to mobile service units and the rules adopted by the municipality are more restrictive than the board’s rules, the rules are not invalid under Subsection (a).

(c) This chapter does not invalidate a municipal or county ordinance or rule that was in effect on September 1, 1969, and that relates to the storage of flammable liquids or relates to or prohibits mobile service units.
(d) The board rules must provide that a facility that is in service before the effective date of an applicable rule and that is not in strict conformity with the rule may continue in service if the facility does not constitute a distinct hazard to life or property. The rules may delineate the type of nonconformities that should be considered distinctly hazardous and the nonconformities that should be evaluated in light of local conditions. The rules must provide that a person who owns a facility affected by the rules receives reasonable notice of intent to evaluate the need for compliance and the time and place at which the person may appear to offer evidence on that issue.