Consumer Affairs

Inspection of Vehicle-Tank Meters
Information Sheet No. 8

Every vehicle-tank meter that dispenses oil in the City of Seattle must be tested and approved by weights and measures inspectors at the Consumer Affairs Unit (Test Station) [Seattle Municipal Code, Section 7.04.145]. Use of a vehicle-tank meter that isn’t approved is a criminal misdemeanor punishable by fine and/or imprisonment [SMC 7.04.690]. A weights and measures inspector will affix a lead-and-wire security seal on the adjustment mechanism of the meter. In addition, paper approval seals will be placed on the meter and in the windshield of the vehicle.

Inspection and test procedures for vehicle-tank meters are contained in Handbook 44 Specifications, Tolerances, and Other Technical Requirements for Weighing and Measuring Devices (1997) published by the National Institute of Standards and Technology (NIST). These inspections and tests are summarized in Examination Procedure Outline (EPO) No. 23 "Vehicle-Tank Meters: Power-Operated" and EPO No. 24 "Vehicle-Tank Meters: Gravity-Discharge".

The inspection will include an examination of the discharge lines and valves, pump (if installed), meter(s), and discharge hose. The tests must be conducted using the same liquid that is commercially measured. One or more "normal" tests are performed at the maximum discharge rate and at flow rates down to one-half the sum of the maximum discharge rate and the minimum flow rate. The test measures used at the Test Station are 300-gallon (heating oil) and 1,000-gallon (gasoline). "Special" tests will be performed for: (1) the minimum discharge rate (usu. 20% of maximum flow rate); and (2) split-compartment delivery (for multi-compartment vehicles). The split-compartment test requires that liquid be discharged from a compartment containing less than one-half the capacity of the test measure (or 150 gallons for heating oil and 500 gallons for gasoline) until the meter stops. Next, with the pump in operation, the valve for that compartment is closed and the valve for another compartment is opened to complete the test.

Calibrate meters for zero error. The tolerances for tests of vehicle-tank meters are as follows:

Maintenace tolerance applies to vehicle-tank meters in commercial use. Acceptance tolerance applies to new equipment and repaired equipment [Handbook 44, G-T.1]

Delivery tickets must be provided for heating oil [SMC 7.04.540]. The delivery tickets must contain the following information: name and address of the vendor, name and address of the purchaser, type of fuel, unit price, quantity delivered, and meter readings.