1. UNC Review Group 0251 Metering Issue for Consideration
21 September 2009

2. Metering - Governance Background
Metering is Governed by DECC and Ofgem
Responsibility is at the terminals
Regulation provide prescriptive arrangements (GCOTE 1997)
Metering predominately Orifice plates (120 / 60)
Purpose for metering developed

3. Ofgem Governance Provided for within the GCOTE
Scope for CV and metering
Requires sites to be directed, setting out performance requirements and Letter of approval
Charging areas defined by industry
Declared or FWACV can be operated
FWACV seeks to protect consumers (1MJ/m^3 c2.5%)

4. Metering Standards Orifice plates standard ISO 5167
UNC OAD appendix D sets out requirements 1.1 % on volume
Disconnect between entry and exit 1991 Vs 2003
Supplementary agreements allow greater uncertainty ?
0 to 30% of flow, +/- 3.6%
30 to 100 % of flow, +/- 2.1%

5. ISO 5167 ISO standards updated approximately every 5 years
Changes to ISO 5167 – 2003
1. Discharge Coefficient
2. Expansibility Factor
3. Permanent Pressure Loss
4. Upstream Temperature
Considered that 1991 overstates when compared to 2003 by approximately 1%, depending upon meter configuration

6. Other Factors and consideration
Fixed factors for
Pressure
Temperature

7. Moving the debate forward
To what extent does the difference in standards and range of uncertainty contribute to shrinkage
Winners and losers
Are localised factors more applicable
Offtake
Consumers meters
This is an area for further work and investigation