There is no fixed number. If the regulator is in good working order, it is permissible to overhaul it every other year with an inspection procedure being performed on the “off” years. A unit that receives heavy or frequent use, such as rental, instruction, or commercial applications, should be serviced at least twice a year - or more often - depending on the conditions of use and the manner in which it is maintained.
If any issues are found during the inspection service, an overhaul may be performed. The parts kit used during the overhaul are free to the customer if the inspection or overhaul has been performed at least every year. The parts are free, but the labor costs for an inspection or overhaul is not.
