Date: 2004-02-23
Bulletin: V-26-E
Category: Volume
Table of contents
1.0 Purpose
The purpose of this bulletin is to address recommendations 6(ii) and 9 of the Downstream Petroleum Trade Sector Review (DPSR): to establish the Measurement Canada (MC) policy for the approval and inspection requirements of ancillary measurement devices for temperature, pressure, and density.
2.0 Scope
This policy applies to ancillary devices for temperature, pressure and density, when used in conjunction with approved weighing and measuring devices used exclusively in the downstream petroleum sector.
3.0 Definitions
- "Device":
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means any weight, weighing machine, static measure or measuring machine and includes any equipment and accessories attached to or used in conjunction with the device that have, or can have an effect on the accuracy of the device. (Section 2, Weights and Measures Act)
Note: Other terms such as "component"or "element", although not defined in the Act or Weights and Measures Regulations are, at times, referenced and used interchangeably with the word "device" throughout weights and measures documentation.
- "Transducer":
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means a device which provides a useable output quantity having a determined relationship to the input quantity to be measured.
4.0 Background
As a result of consultation with stakeholders in the downstream petroleum sector, the following recommendations were submitted to, and approved by, the Senior Management Committee of MC:
Recommendation 6(ii): MC… clearly define whether ancillary device components (i.e., pressure, temperature and density) be approved separately, or as part of a complete measuring system.
Recommendation 9: MC… clearly define whether ancillary device components (i.e., pressure, temperature, and density) be inspected and certified separately, or as part of the complete measuring system.'
5.0 Policy
5.1 Pressure
5.1.1 When installed as part of a liquid measuring system, a pressure transducer shall be approved separately as a device, as defined under the Weights and Measures Act (WMA), or approved as a function of another device, such as an electronic register, and initially inspected in-situ and periodically re-verified as part of a complete measuring system inspection. Pressure transducers of the same model and manufacturer may be replaced without the need for a new initial inspection. In most cases, the function of pressure is used for calculating net volumes at reference conditions as determined by an approved electronic register or flow computer. In some cases, the pressure is used in conjunction with the temperature to provide input to pressure controlling valves.
5.1.2 Approved pressure transmitters of both the regular type and smart type, are designed with a sealable cover to prevent unauthorized access and must be properly configured at installation. Whenever a seal is broken to effect repairs or replacement of the device, normal reporting requirements to the nearest Measurement Canada office apply.
5.1.3 Pressure transducers will continue to be evaluated against the draft Ministerial Specification for Pressure Transducers, until such time as this draft specification is promulgated. Electronic registers that have provision for automatic pressure compensation (APC), will continue to be evaluated and approved against draft the Ministerial Specification - Electronic (APCs) Incorporated into Electronic Registers.
5.2 Temperature
5.2.1 When installed as part of a liquid measuring system, a temperature transducer shall be approved separately as a device, as defined under the WMA, or approved as a function as part of another device, such as an electronic register. In all applications, the function of temperature is used for calculating net volumes at reference conditions as determined by an approved electronic register or flow computer.
5.2.2 Temperature transducers will continue to be approved against the existing Ministerial Specifications for electronic registers (SVM-1) and automatic temperature compensation (SVM-2). Temperature transducers installed as a separate device or as a function of an electronic register, will continue to be initially inspected and periodically re-verified in-situ as part of a complete measuring system inspection in the future. Instruments of the same manufacture, model and resistance temperature detector (RTD), may be replaced without the need for a new initial inspection. Whenever a seal is broken to effect repairs or replacement of the device, normal reporting requirements to the nearest Measurement Canada office apply.
5.3 Density determination devices
5.3.1 To date, MC has taken the position of not requiring the approval or inspection of density devices used in trade transactions for the temperature correction of petroleum products. Density equipment that is used in conjunction with approved measuring devices in the downstream petroleum sector are believed to be periodically calibrated to the satisfaction of the trading parties involved. To date, there have been no requests from industry for MC to approve these type of devices when used for temperature correction purposes.
5.3.2 Until further notice, the status quo shall prevail, with no specification or procedures being required for density devices. However, this will not preclude density equipment from having to be accurate and used correctly as outlined in section 3 of the MC Bulletin V-18 (rev.4), Selection of Volume Correction Factor Tables and Mean Density Values for Some Common Products when used for the purpose of temperature correction.
5.3.3 In the unlikely situation where a density device is used in a trade transaction to convert a quantity of product measured in terms of volume to a declared quantity on the basis of mass, then MC would have to assess the proposed measurement transaction to determine if the density device would need to be approved or inspected. The current commodity limits of error for transactions in mass units of measure make the conversion very difficult to be done accurately.
5.3.4 However, if the product is measured in terms of mass and converted to a declared quantity in terms of volume, then the process shall be fully automatic (no manual density measurement for input into a computer for calculation), and the density device shall be approved as a separate device, initially inspected and periodically re-verified thereafter. Where the proposed measurement practice for mass to volume conversion is deemed to be impractical due to the nature of the product to be measured (e.g., multi-product viscous applications), MC will review installations on a case-by-case basis to seek compliance with the intent of this policy.
5.3.5Measurement Canada will commence research into the technical requirements for density measuring devices with the view to adopt existing international specifications, such as OIML R-117, Measuring Systems for Liquids Other Than Water, if appropriate, or develop specifications for the approval and inspection of density devices for the Canadian market. The agency will continue to consult with industry on the development or adoption of specifications for density devices and to identify the future date when the new requirements will come into effect.