Meter installation

Meters · for gas engineers in training

From the ECV to the bonding clamp

Every UK meter installation is the same few parts in the same order. Gas comes up the service to the ECV, through the meter connector to the regulator, then through the meter and out of its outlet union into the installation pipework. A bracket on the wall holds the meter up by its unions. Step through them in the order the gas meets them. Then turn appliances on and off and read the standing and working pressure at the test point. Cut it open to watch the gas go through: the darker the blue, the higher the pressure. Last, find where the bonding goes.

OFFONGAS EMERGENCYCONTROLONOFFIF YOU THINK YOU CAN SMELL GASTurn off the supply at the control valve. Open doors and windows.Do NOT use naked flames. Do NOT turn electrical switches on or off.Do NOT smoke.IMMEDIATELY CONTACT THE GAS EMERGENCY SERVICE.THE TELEPHONE NUMBER IS0800 111 999Do NOT reopen the supply until remedial action has been takenby a competent person to prevent gas escaping again.METER EXCHANGE / FIX DETAILSOLD METER NOOLD METER INDEXNEW METER INDEXDATEIF METER BANKGIVE FLAT No.G4SAFETY ELECTRICALCONNECTIONDO NOT REMOVE
Follow the gas
View
ECV
Appliances on
Flow–m³/hAt the ECV–mbarRegulator out–mbarTest point–mbar

Sources

  1. IGEM/G/1 Edition 3: the Network ends at the ECV outlet; the primary meter installation ends at the outlet of the meter outlet union.
  2. Gas Safety (Installation and Use) Regulations 1998, reg 9: the ECV, its access, its on and off positions and the emergency notice.
  3. BS 6400-1: installation of domestic-size gas meters; 21 mbar nominal at the meter outlet.
  4. IGEM/GM/PRS/3 7.2 and CCN1 Issue 16, sections 7 and 16: working pressure 19 to 23 mbar; lock-up no more than 30 mbar in service.
  5. IGEM/UP/1B: tightness testing and purging of small low-pressure installations, with the gauge on the meter outlet test point.
  6. BS 6891: installation pipework; sleeves through walls, sealed at one end.
  7. BS 7671:2018+A2:2022, 544.1.2 (main protective bonding of gas pipes: within 600 mm of the meter outlet union or at the point of entry), 514.13.1 (the label), Table 54.8 (10 mm² for a PME supply). BS 951 earthing clamps.
  8. Meter bracket, security washer and shear bolt: BES parts 8211, 8212 and 8213. The bracket hangs a G4 or U6 meter on grooved unions slid into slots at 152.4 mm centres; the washer and shear bolt stop a union being slid out.
  9. Meter: GWi G4 1.2L TVI general arrangement, as in the meter figure. Regulator: a Sperryn G940 Mk 3, to the sizes in its datasheet (Sperryn S-G940Mk3-0113), as in the regulator figure; its droop curve follows the datasheet's PRS3 test curve. ECV: a 3/4 in BES 10526 valve, as in the ECV figure.

Drawn to one scale in millimetres, without the house or meter box, so every part shows. The ECV, meter connector, regulator and meter are the parts drawn in the ECV, regulator and meter figures; the regulator is a Sperryn G940 Mk 3 at its datasheet's sizes. Pressures are the G940's droop curve from the regulator figure less the meter figure's pressure loss, so they are typical, not measured. The cross-section cuts every part on the plane of the gas path; the meter's measuring unit in it is simplified to its chambers, diaphragms, valve grid and outlet tube, and its diaphragms and slide valves move as in the meter figure, one crank turn for every 1.2 litres the index counts. Each of its four compartments fills from the case and empties to the outlet through the same port as its diaphragm moves, the slide valve switching that port over at the end of each stroke; the compartments filling are shaded darker.