All liquid measuring equipment in service and all attached mechanisms and devices or those used in connection therewith must continuously be maintained in proper operating condition throughout the period of service of the equipment. Liquid measuring devices in service at a retail facility found to be in error predominately in a direction favorable to the measuring device owner or operator and near the tolerance limits are not considered to be maintained in a proper operating condition.
Okla. Admin. Code § 165:15-15-40