(a) Test standards must be certified annually by a recognized or accredited laboratory that adheres to ISO 17025 standards. A service company must maintain at least one test standard per licensed device category as follows:(1) Low flow: five-gallon or greater test measure or prover;(2) High flow: prover with a capacity that exceeds the amount of liquid delivered by the device in one minute at the maximum flow rate.(b) A test standard that becomes damaged must be taken out of operation immediately and recalibrated prior to use. A test standard that is beyond repair must be taken out of service permanently.(c) A service company must maintain the minimum test standards per licensed device category at all times.