At any installation where the normal flow of product may be stopped other than by the hose nozzle valve e.g., at pre-pay stations, the system must include UL listed equipment with a feature that causes or requires the closing of the hose nozzle valve before product flow can be resumed or before the hose nozzle valve can be replaced in its normal position in the dispenser.
Okla. Admin. Code § 165:25-2-73