PS-G-15 (rev. 1) — Provisional Specifications for the Approval, Verification, Installation and Use of Fluidic Oscillation Meters

PS-G-15 – Provisional Specifications for the Approval, Verification, Installation and Use of Fluidic Oscillation Meters, in PDF format, 113.9 KB


Date: 2008-10-15
Bulletin: PS-G-15 (rev. 1)
Category: Gaz
Supersedes: PS-G-15


PS-G-15 (rev. 1): Summary of Amendments to PS-G-15
Section Description
3 Updated heading to “Terminology”.
5 Removed subsections 5.1.1 to 5.1.4 and renumbered the remaining subsections to reflect the removal. The subsections removed are adequately addressed in LMB-EG-08.
6.1 Added a reference to section 3-5 of LMB-EG-08 and removed requirements that are adequately addressed in LMB-EG-08.
7.0 Added a revision section. This section is used to maintain a log of the purpose for each revision to documents.

Table of Contents


1.0 Scope

These specifications apply to fluidic oscillation gas meters which operate by integrating gas flow through the detection of a gas jet’s oscillation frequency.

2.0 Authority

These specifications are issued under the authority of sections 12 and 18 of the Electricity and Gas Inspection Regulations.

3.0 Terminology

Deviation

The mean of the errors at a given flow rate.

Error

The difference between the volume measured by the meter under test and the volume measured by a reference meter. Corrections must be made for the differences of gas pressure, temperature, and compressibility between the two meters. The error shall be calculated according to clause 4.1.1.3.

FWME

The flow rate weighted mean error of a meter, calculated according to clause 4.1.1.4.

Linearity

The maximum difference between the meter’s FWME and any of the error deviations for test points between the maximum and minimum rated flow rates.

Maximum permissible error

The largest allowable deviation within the specified operational range of the meter.

Minimum flow rate (Qmin)

The lowest flow rate at which the meter’s error is less than the maximum permissible error and the linearity is less than the maximum prescribed value.

Maximum flow rate (Qmax)

The maximum rated flow rate of a meter, as listed in the Notice of Approval.

Reference meter

A meter (or test facility) of known accuracy.

Repeatability

The largest spread of errors of a given meter when several successive measurements are performed at the same flow rate under the same operating conditions.

Reference Conditions

Ambient temperature of 23°C ±2°C and flowing test medium temperature within ±0.5°C of ambient temperature.

Fluidic Oscillation meter

A meter consisting of a meter body designed to condition gas flow into jet formation (flow conditioner and jet nozzle), a fluidic oscillation chamber (flow obstacle and sensors), and associated signal processing circuitry.

4.0 Metrological Requirements

4.1 Maximum Permissible Errors

4.1.1 Pattern Approval Accuracy Tests at Reference Conditions

4.1.1.1

Meters shall be tested using a suitable test medium 1 at flow rates over the range of 10% to 100% of Qmax, at flowing gas pressures over the specified operating pressure range of the meter 2. Each test point shall consist of at least three measurements, each measurement being of sufficient duration to provide an error resolution of 0.1% or better. The tested flow rates shall be approximately equally spaced between 0.1Qmax and Qmax, and shall include as a minimum; 0.1Qmax3, 0.25Qmax, 0.5Qmax, 0.75Qmax and Qmax.

NOTE 1: The test medium will normally be natural gas. However, if an applicant provides data demonstrating that other media are suitable for performing tests, tests on those media will be accepted. Unless otherwise specified in the Notice of Approval, a meter shall be calibrated at or near its intended operating conditions using the intended gas.

NOTE 2: Where test facilities are not available to perform tests over the entire operating pressure range of the meter, the applicant shall provide test data demonstrating that the pattern to which the meter belongs is insensitive to operating pressure.

NOTE 3: 0.1Qmax = Qmin

4.1.1.2

The errors of the meter between Qmin and Qmax shall not exceed the following tolerances:

Table 1
Maximum permissible error: ±1.0%
Repeatability: ±0.2%
Linearity: ±0.5%
4.1.1.3 Calculation of Error

Error (%) = [(volume at test meter − volume at reference meter) ÷ volume at reference meter] × 100

4.1.1.4 Calculation of Flow Weighted Mean Error (FWME)

The FWME shall be calculated as follows:

FWME (%) = ((Q1 / Qmax) × D1 × W1 + (Q2 / Qmax) × D2 × W2 + … + (Qn / Qmax) × Dn × Wn) ÷ ((Q1 × W1) / Qmax + (Q2 × W2) / Qmax + … + (Qn × Wn) / Qmax)

where, Qi is the test flow rate, and Di is the deviation at the tested flow rate Qi. When Qi ≥ 0.95Qmax, Wi = 0.4, otherwise Wi = 1.0

4.1.2 Pattern Approval Accuracy Tests at Other than Reference Conditions

4.1.2.1

Meters shall be tested at a pressure within the meter’s intended operating range and at a flow rate of 0.25Qmax. Tests shall be conducted at an ambient temperature of −30°C with the flowing gas temperature at 0°C and −10°C 1, and at 40°C with a flowing gas temperature of +10°C and +30°C. The errors of the meter shall not exceed those set out in clause 4.1.1.2.

NOTE 1: Means shall be implemented to prevent the accumulation of moisture in the meter during tests conducted at other than reference conditions. Depending on the dew point of the test medium, some of the required temperature values may not be feasible. In these instances, the largest differential temperature obtainable shall be considered. The meter shall be subjected to the test temperatures for a length of time as is necessary to establish thermal stability.

4.1.2.2

A meter shall remain within the specified tolerance when subjected to normal pulsations and flow disturbances.

4.1.2.3

Where it can be shown that a meter’s accuracy is susceptible to flow pulsations, the Notice of Approval shall indicate the appropriate means to use to reduce the intensity of such disturbances to a level which will not cause the meter’s accuracy to exceed the maximum permissible error tolerance specified in clause 4.1.1.2.

4.1.2.4

In addition to the approval requirements listed in this provisional specification, fluidic oscillation meters shall also be evaluated against the applicable requirements in sections 3, 4,15, and 21 of LMB-EG-08, Specifications for Approval of Type of Gas Meters and Auxiliary Devices, 1987.

4.1.3 Verification and Reverification Accuracy Tests

4.1.3.1

Subject to clause 4.1.3.2, tests shall be conducted on a suitable test medium 1 at a pressure which is representative of the meter’s intended use. Where Qmax cannot be achieved because of limitations of the test facility, the upper test flow rate shall be at least 0.4Qmax and the meter shall be tested at at least five flow rates approximately equally spaced between 0.1Qmax and the maximum flow rate attainable by the test facility.

NOTE 1: The test medium will normally be natural gas. However, if an applicant provides test data demonstrating that other media are suitable for performing tests, tests on those media will be accepted, and use of that test media authorized in the Notice of Approval.

The maximum permissible error of the meter shall not exceed the tolerances set out in clause 4.1.1.2. Where the meter’s maximum test flow rate cannot be achieved, the errors of the meter shall not exceed the following tolerance limits:

Maximum permissible error: ±1.0% × %Qmax attained ÷ 100

where, %Qmax attained is the highest test flow rate attained.

4.1.3.2

Fluidic oscillation gas meters may be verified or reverified using appropriately certified proving technologies. Where fluidic oscillation gas meters are verified using a measuring apparatus which performs testing at low pressure using air as the test media, the test points shall be equal to 0.2Qmax ±0.05Qmax and 0.95Qmax ±0.05Qmax. The test duration shall be sufficient to ensure an error resolution of 0.1% or better.

Maximum permissible error: +1.0%

Where the 0.95Qmax (+ 0.05Qmax) test point cannot be achieved because of limitations of the test apparatus, the upper test flow rate shall be at least 0.5Qmax, and the errors of the meter shall not exceed the following tolerance limits:

Maximum permissible error: ±1.0% × %Qmax attained ÷ 100

4.1.3.3

In addition to the tests required by clauses 4.1.3.1 and 4.1.3.2, meters that contain one or more volume conversion functions shall be tested in accordance with the applicable requirements of Measurement Canada’s generic inspection procedure for electronic volume conversion devices, Class 8, revision A, 2002-11-25.

4.2 Verification Requirements

4.2.1

The Notice of Approval shall be referred to for information regarding parameters in the processing circuitry which may need to be changed or programmed at the time of verification prior to meter sealing.

4.2.2

The meter shall be examined for conformance with the marking requirements prescribed by clause 6.1

4.2.3

Unless otherwise noted in the Notice of Approval, as per clause 5.1.8, the volume indication on a meter’s electronic display need not be verified by means of a volume accumulation test, provided that a verification check is performed to ensure that the registered reading on the display matches the reading obtained using meter interrogation software.

4.3 Reverification Requirements

4.3.1

Meters shall be submitted for reverification at least every six years. The requirements for reverification are the same as for verification.

4.4 Conditions for Metrological Characteristics

4.4.1 Influence and Disturbance Factors

For pattern approval purposes, the meter volumetric accuracy tests shall not exceed the errors set out in clause 4.1.1.2, over the following range of influence and disturbance factors:

4.4.1.1

Influence factors: As set out for Class F meters in sections 9 and 10 of International Organization of Legal Metrology R-6, "General Provisions for Gas Volume Meters - 1989".

4.4.1.2

Swirl susceptibility: The inlet to the installation configuration recommended by the manufacturer shall be preceded in turn by a clockwise and a counter clockwise swirl generator, constructed of two ninety-degree elbows connected together orthogonally.

5.0 Technical Requirements

5.1 Design, Composition, and Construction

5.1.1

A pressure tap shall be located on the meter body.

5.1.2

The meter shall provide for registration of the volume of gas which has passed through it. Where the meter incorporates provisions for converting volume to base conditions of temperature and pressure, the meter shall be capable of registering both converted and unconverted volume.

5.1.3

Once sealed, the display register of a meter designed to register cumulative volume shall not be resettable under normal conditions of use.

5.1.4

At the time of approval evaluation, fluidic oscillation meters equipped with an electronic register display shall be evaluated to determine if the register’s volume reading is derived from the same memory location as the output signal used for gating the prover during calibration accuracy testing. If the meter is not of such design, then the Notice of Approval shall note that fact and/or stipulate that a volume accumulation test is to be performed during verification.

5.1.5

The meter shall use the standard communication protocol set out in ANSI C12.18-1996 and IEEE P1377 / ANSI C12.19-1996, or the manufacturer shall provide, free of charge, software which is executable on a recent release of the Microsoft disk operating system (MS-DOS) platform or Microsoft Windows, or compatible, to interrogate, control, and verify the meter. The executable software shall be provided on diskette(s) formatted for IBM-compatible personal computers. If applicable, operating manuals and documentation may (by preference to printed material) be provided electronically in a standard format for IBM-compatible personal computers. The software shall preclude the possibility of disruption of the meter’s operation during the verification process. Measurement Canada hereby undertakes to ensure that the software will be used solely for the purpose of inspection of meters by government inspectors and not to disclose the contents of the software or its documentation to third parties.

5.2 Installation and Use

5.2.1

The meter shall be installed in a manner designed to prevent the accumulation of contaminants.

5.2.2

Unless otherwise stated in the Notice of Approval, the meter shall be installed either vertically or horizontally. In a vertically installed meter, the gas shall flow downward.

5.2.3

Where a meter is subject to flow pulsations and it has been shown that the meter’s accuracy is affected by such disturbances, appropriate provisions shall be made to reduce the intensity of the disturbance to a level that will not induce a measurement error greater than the maximum permissible error specified in clause 4.1.1.2.

5.2.4

Where conditions of reverse flow may occur during meter usage, the installation shall incorporate provisions to prevent the reverse flow of gas.

5.2.5

The meter shall not be used outside the range of ambient temperature for which it is approved. Where necessary, shelter and heaters or other arrangements shall be provided to ensure that this requirement is met.

5.2.6

Only the approved meter output(s) which is(are) proportional to the volume of gas which has passed through the meter shall be used for billing calculations.

6.0 Administrative Requirements

6.1 Markings

In addition to the approval requirements listed in section 3-5 of LMB-EG-08, the following information shall be indelibly marked on, or be capable of being displayed, by the meter:

  1. minimum and maximum flow rates (at line conditions)
  2. minimum and maximum operating pressures
  3. the base temperature value, where the meter performs volume conversion for flowing gas temperature. Where this information appears on the nameplate, it shall be permanently and prominently indicated irrespective of background colour.
  4. the base pressure value, where the meter performs volume conversion for flowing gas pressure
  5. ranges of the measurement parameters for which the device is intended
  6. any user-programmable factors (where used)
  7. space shall be provided for an inspection number
  8. type, range, and pulse weight of output signal(s) (as applicable)
  9. firmware version

6.2 Sealing

The verification marks for the meter shall take the form of a seal applied to prevent unauthorized access to metrological adjustments, and shall be applied at the time of verification or reverification. The Notice of Approval should be referred to for any particular sealing requirements.

7.0 Revision

The purpose of this revision is to remove requirements identified under the Government of Canada paper burden reduction initiative.

Alan E. Johnston
President
Measurement Canada