S-G-03–Specifications for the approval of type of gas meters, ancillary devices and associated measuring instruments

Category: Gas
Issue date:
Effective date:
Revision number: 1
Supersedes: LMB-EG-08 and S-G-03


Part 15: Dispensers for natural gas

Table of contents


1.0 Scope

This part of the Specifications applies to dispensers of gas submitted for approval and used for the refuelling of motor vehicles, tanks and storage cylinders.

2.0 Units

The applicable requirements of Part 1, section 6.0 shall apply unless otherwise stated in this section.

2.1 The preferred unit of registration is the kilogram or the megajoule. If the commodity is registered in units of volume, the volume shall be converted to standard conditions.

3.0 Metrological requirements

The applicable requirements of Part 1, section 7.0 shall apply unless otherwise stated in this section.

3.1 Total delivery display error

The error of the total delivery display shall not exceed the applicable MPEs in Part 15, Table 1.

Part 15, Table 1: Gas dispenser maximum permissible errors
Test conditions Working pressure (pw) MPE
Reference As specified in 7.2.1.1 ± 1%
60% and 80% of the reference pressure specified in subsection 7.2.1.1 ± 1.5%
"Other than reference" As specified in 7.2.1.1 ± 2%

3.2 Total sale display

The total sale display shall agree to within ± 1 cent with the value obtained by multiplying the displayed price per unit delivery by the total delivery.

3.3 Display reset

Where a mechanical display is used with a dispenser, the error in resetting the display to zero shall not exceed 3° of movement from an indicator mark.

3.4 Preset quantity

Where the quantity of gas to be delivered is preset, the dispenser shall deliver at least the preset quantity ± 1 minimum increment set forth in 4.1.1(a) according to the display of the dispenser before the flow is automatically stopped.

3.5 Preset sale

Where the total sale of the gas to be delivered is preset, the dispenser shall deliver at least the preset total sale ± 1 cent according to the display at the dispenser before the flow is automatically stopped.

4.0 Technical requirements

The applicable requirements of Part 1, section 8.0 shall apply unless otherwise stated in this section.

4.1 Indicating devices

4.1.1 Dispensers shall be equipped with an indicating device with a display of total delivery as follows:

  1. Total delivery display: The capacity of the display shall be not less than 99.999 kg with a resolution of at least 1 g, or 9999.9 MJ with a resolution of at least 0.1 MJ, or 99.999 std m³ with a resolution of at least 0.001 std m³ (9999.9 std ft³ with a resolution of at least 0.1 std ft³).
    1. The display shall be resettable to zero.

4.1.2 Price computing indicating devices shall also have the following displays:

  1. Total sale display: The capacity of the display shall not be less than $99.99, with a resolution of 1 cent.
    1. This display shall be resettable to zero.
  2. Unit price display: This shall be an adjustable display with a resolution of 0.1 cents per unit of metered quantity.

4.2 Electronic indicating devices

4.2.1 Indicating devices with electronic displays shall either:

  1. automatically show all display segments for at least 0.5 seconds and blank for at least 0.5 seconds after a register is reset to zero and before another delivery is started to allow an operator to detect a segment that either indicates continuously or does not indicate; or
  2. incorporate an automatic self-testing system which checks the correct operation of all display elements prior to commencing a delivery and on detection of a fault prevents further use of the register.

4.2.2 The quantity indications, unit price and total price indications shall remain displayed for at least five minutes after a delivery is completed or until the next transaction is initiated or the current transaction is finalized.

4.3 Interlocks

4.3.1 Indicating devices

A dispenser shall be designed so that it is inoperable after a transaction is completed until the resettable indicating devices are reset to zero by means of an automatic interlock.

4.3.2 Hose pressure

Delivery hoses and piping downstream of the meter shall not exceed 500 cm³ in volume unless the hoses are automatically filled with gas at the delivery pressure before a zero condition is established on the total delivery and total sale displays.

4.4 Ticket printer

4.4.1 Ticket information

4.4.1.1 Where a ticket printer forms part of or is used in conjunction with a dispenser, the ticket shall carry the following information:

  1. Name of the contractor and address at which the dispenser is installed;
  2. An identification number for the meter, or if there is only one meter, the identification number of the dispenser;
  3. The total delivery and units indicated by the register;
  4. Unit price of gas delivered (where used with a price computing register);
  5. Total sale indicated by the register (where used with a price computing register);
  6. Date that the delivery was made;
  7. An automatically advanced sequential sales number.
4.4.2 Ticket printer interlock

Where a ticket printer is provided with a dispenser, an interlock shall be incorporated such that a ticket is printed for every transaction.

4.5 Dispenser configuration

Dispensers intended for refuelling from both sides shall have indicators on both sides.

4.6 Reverse flow prevention

There shall be means provided to prevent flow from the vessel back through the dispenser in the event that the vessel to be refilled has a higher initial pressure than the dispenser delivery pressure.

4.7 Power mains failure

4.7.1 Dispensers which operate from the mains power supply shall, in the event of a power outage, either:

  1. continue to operate satisfactorily for:
    1. 24 hours where a back-up supply which automatically recharges upon restoration of the power is used; or
    2. 7 days where any other type of backup supply is used; or
  2. retain programming and metering information for the applicable period as specified in 4.7.1(a), and shall be capable, upon demand, of displaying quantity, unit price and total price at any time up to 15 minutes after the power outage.

5.0 Marking requirements

In addition to the applicable requirements of Part 1, section 9.0, the following shall apply.

5.1 Where the flow rate range is not the same for all hoses, the flow rate range for each group of hoses shall be marked.

5.2 Each Coriolis mass flow meter, remote electronics unit and printer (where it is located on/in the dispenser) shall bear a nameplate showing the markings required in Part 1, 9.1.3(b), (c) and (d) of the component.

5.2.1 Each Coriolis mass flow meter shall comply with the marking requirements of Part 6, section 5.0.

5.2.2 Nameplates shall be clearly visible with the cover(s) removed.

6.0 Sealing requirements

The applicable requirements of Part 1, section 10.0 shall apply unless otherwise stated in this section.

6.1 Indicating devices

Indicating devices of dispensers for natural gas are exempt from the requirement specified in Part 1, 10.5.

6.2 Assembly

Where a dispenser comprises more than one separate assembly, the interconnecting cables and tubing shall be so arranged as to be capable of being sealed in a manner which will prevent replacement of any assembly without breaking a seal.

6.3 Provision for price adjustment

There shall be provision for adjusting the price per unit of the commodity being sold without the necessity of breaking a seal.

6.4 Security of price adjustment

Access to the price setting mechanism shall be limited to authorized personnel by provision of a lock and key arrangement or equivalent.

6.5 Price

It shall not be possible to change the unit price during calculation of the total price for any given delivery.

6.6 Ticket printer

Where a ticket printer forms part of or is used in conjunction with a dispenser, the ticket printer shall be designed so that a jammed ticket can be removed without breaking any inspection seals.

6.7 Adjustments

6.7.1 Adjustment range of ± 2%

6.7.1.1 The maximum range of any adjustment affecting the accuracy of the total delivery display which is accessible without removing a portion of the exterior housing shall not exceed ± 2%.

6.7.1.2 Such external adjustments shall not be capable of being changed when the dispenser is in use.

6.7.1.3 Except in the case of a zero adjustment, the dispenser shall be sealable.

6.7.2 Greater than ± 2% adjustment range

Any adjustment for accuracy of range exceeding ± 2% shall not be accessible without removing a sealable portion of the dispenser housingFootnote 15-1 and shall itself be sealable.

7.0 Performance tests

The applicable requirements of Part 1, section 12.0 shall apply unless otherwise stated in this section.

7.1 General

7.1.1 Prior to commencing tests, the display of total delivery shall be adjusted to indicate as close to zero error as practicable.

7.1.2 No test shall result in a delivery of less than one kilogram or the minimum measured quantity.

7.1.3 Test cylinders having an initial pressure within the range from atmospheric to the declared maximum delivery pressure of the dispenser shall be partially or completely filled.

7.2 Test conditions

7.2.1 Operating conditions
7.2.1.1 Reference and "other than reference" working pressure
  1. For dispensers incorporating the pressure control equipment required by CSA B149.1-10, the reference pressure at the inlet to the dispenser shall be 22 MPa or the maximum rating declared by the manufacturer, whichever is lower.
  2. For dispensers not incorporating the pressure control equipment required by CSA B149.1-10, the reference pressure at the inlet to the dispenser shall not exceed that required by CGA B-149.
7.2.2 Test medium

The test gas used is normally compressed dry air, properly filtered to remove foreign matter.

7.3 Evaluation tests

7.3.1 Accuracy testing

7.3.1.1 At reference conditions, tests shall be performed at test points distributed over the measuring range with a test medium as specified in 7.2.2 at a working pressure as specified in subsection 7.2.1.1 (see Part 15, table 2).

7.3.1.2 Tests specified in 7.3.1.1 shall be repeated at working pressures set at 60% and 80% of the reference pressure specified in subsection 7.2.1.1 (see Part 15, table 2).

7.3.1.3 At "other than reference" conditions, tests shall be performed at test points distributed over the measuring range with a test medium as specified in 7.2.2 at a working pressure as specified in subsection 7.2.1.1 (see Part 15, table 2).

Part 15, Table 2: Gas dispenser accuracy testing
Test medium Environmental conditions Working temperature (tw) Working pressure (pw)
Compressed dry air Reference Reference As specified in 7.2.1.1
60% and 80% of the reference pressure specified in subsection 7.2.1.1
"Other than reference" "Other than reference" As specified in 7.2.1.1

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