1. Sections 265 to 270 of the Weights and Measures Regulations state that acceptance limits of error set out in column II of the appropriate tables apply only to tests made under controlled conditions. For tests made under other conditions, the acceptance limits of error are set out in column III of those tables.

2. Pressure, temperature and flow rate are the primary factors which affect test results. In order to consider test conditions as "controlled" the effect of these factors must not cause a change in the test volume by an amount greater than 1/3 of the applicable limit of error for the device.

3. In order to evaluate the performance of a meter within the accuracy stated in column II of the tables of sections 265 to 270 of the Regulations, an inspector must be able to control the change in temperature, pressure or other factors between the meter and the test measure within strict limits or alternatively, correction factors must be applied to the indicated volumes.

4. The following defines the controlled conditions to be applied to meters indicating in volumetric units of measure, when volumetrically tested to acceptance limits of error in laboratories, dealers' or manufacturers' premises.

4.1 Flow Rate Variation: The volumetric flow rate shall be stable to within ±10% of the maximum rated meter flow rate for 90% of the test volume.

4.2 Fast Flow Rate: Unless authorized by Measurement Canada's Engineering Directorate, the fast flow test shall be performed at a minimum of 80% of the maximum rated meter flow rate.

4.2.1 Fast flow tests at rates less than those prescribed may be conducted provided that:

4.2.1.1 documentation and test results supporting the proposed flow rates are submitted and approved by Measurement Canada's Engineering Directorate; and

4.2.1.2 the reduced flow rate will provide results consistent with those at the prescribed rate.

4.3 Slow Flow Rate: The slow flow test shall be performed at a flow rate greater than the minimum rated flow rate of the meter. The flow rate shall be determined by summing the minimum rated flow rate of the meter and 10% of the value of the maximum rated flow rate of the meter. The applicable slow flow rate can be calculated as follows:

Minimum rated flow + (Maximum rated flow rate x 0.1).

4.4 Test Volume: The test volume used shall not be less than:

	5 litres for slow flow meters with maximum flow rates of 10 L/min or less;

	20 litres for gasoline dispensers with maximum flow rates of 90 L/min;

	250 litres for refuellers with a maximum flow rate between 91 and 225 L/min (includes marine and truck refuellers and key locks).

4.5 For meters indicating in volumetric units, and with a maximum flow rate in excess of 250 L/min, a volumetric measure with a standard nominal capacity as close as practicable to the volume displaced by the meter in a period of one minute shall be used.

4.6 When a meter is evaluated using a pipe prover, the guidelines provided in the Measurement Canada training manual Operation and Use of Pipe Provers for Liquid Measurement shall apply.

4.7 Temperature Stability: The temperature, as measured in or near the meter, shall not vary more than ±2 ºC (of the mean) during any flow test.

4.8 Temperature Differences: The temperature of the test liquid, as measured in or near the meter, shall not, during any flow test, vary more than ±1 ºC from that measured in the test measure.

4.9 Temperature Correction: When a flow test requires that a measure with a nominal volume in excess of 100 litres be used, and in the case where the temperature varies more than ±2 ºC from the measure's base calibration temperature, a mathematical correction for the change in the test measures capacity shall be made.

4.10 Pressure: The pressure of the product in the metering system shall not vary more than ±100 kPa (of the mean) for normally liquid products and ±50 kPa for liquefied propane gas (LPG) during a single flow test.

4.11 Pressure Correction: When a flow test requires that a measure with a nominal volume in excess of 20 litres be used, and in the case where the pressure varies , in the case of normally liquid products, more than ±100 kPa and, in the case of LPG, ±50 kPa, from the measure's base calibration pressure, a mathematical correction for the change in the test measures capacity shall be made.

4.12 Product Composition: The composition of the product shall not change during the evaluation of the meter in an amount that will produce an error in excess of 1/3 the applicable limit of error for that meter. The product used shall be approved by Measurement Canada.

4.13 Environmental Conditions: When using an open volumetric measure, the temperature of the test liquid shall not be less than the dew point temperature of the air in the area where the test is being performed. Note that this requirement ensures that moisture in the air does not condense inside of open test measures resulting in a systematic error.

5. The following defines the controlled conditions to be applied to automatic temperature compensators (ATC) incorporated into refuellers, gasoline dispensers, slow flow meters and other meters indicating in volumetric units of measure when tested to acceptance limits of error in laboratories, dealers' or manufacturers' premises.

5.1 Temperature Stability: The temperature, as measured in or near the meter, shall not vary more than ±0.3 ºC (of the mean) during any test.

5.2 Flow Rate Variation: The volumetric flow-rate must be stable to within ±10% of the maximum rated meter flow rate for 90% of the test volume.

6. In the field, inspectors may not normally have the means to adequately control temperature and pressure to the above conditions and, therefore, correction factors will be required.

7. The conditions outlined in this bulletin are effective 1996-05-30 and immediately for companies seeking accreditation under the Accreditation for Initial Factory Inspections of Dispensers and/or Refuellers.

8. For additional information, please contact:

Ted Kingsbury
Senior Program Officer, Volume Measurement
Measurement Canada


		Created: 2003-07-08 Updated: 2005-01-25	Top of Page	Important Notices