Drum-type Gasmeters TG-Series (Wet-Type)

Operation Instructions – Initial Set-up (Chapter 2)

2.1. High-Pressure Gas Meters (> 1bar)

Before performing the initial set-up please read the general instructions in Point “High Pressure Gas Meters and continue installation with point 2.2.

2.2. Positioning

Place the drum-type gas meter onto a solid, vibration-free support. Align the gas meter precisely horizontally by means of the integrated level (at top of casing) and the levelling feet.

2.3. Filling with the packing liquid

Standard-Gas Meters:

• TG 01
  Remove the screwed cap of the High Precision Packing Liquid Level Indicator HPLI“ on the outer end of the glass tube by unscrewing it (please refer to the Data Sheet HPLI“ as well). Open the filling nozzle located at the rear plate by turning the sealing screw anti-clockwise until it is unscrewed. Pour the chosen packing liquid into the gas meter through the filling nozzle.
• TG 05 – TG 50
  Open the filling-level indicator located at the rear plate by turning the sealing screw 2 or 3 times anti-clockwise. Please pay attention, that the screw is not unscrewed out of the thread. Open the filling nozzle located at the rear plate by turning the sealing screw anti-clockwise until it is unscrewed. Pour the chosen packing liquid into the gas meter through the filling nozzle.
• High-pressure Gas Meters
  Loosen and remove the sealing screw of the filling nozzle (hexagonal screw). Pour the selected Packing Liquid into the Gas Meter via the filling nozzle. After setting the Packing Liquid level correctly as described in Point 2.4, replace the sealing screw and firmly tighten it with a spanner.

2.4. Quantity of packing liquid (Adjusting the packing liquid level)

The amount of packing liquid depends on the gas meter size (type) and on the individual setting for each unit. The approximate quantity is shown in the data sheet enclosed with every gas meter. This quantity does not take into account individual differences based on the calibration performed in the factory.

Fine adjustment of the packing liquid level is of greatest significance to the measuring accuracy, since the measuring accuracy/display depends directly on the packing liquid level and reacts very sensitively to an incorrectly set level!

The correct packing liquid level is set as follows:

• For Gas Meters with the High Precision Packing Liquid Level Indicator (HPLI) (optional extra): please refer to the relevant HPLI Data Sheets.
• For Gas Meters with the standard Packing Liquid Level Indicator (located on the rear plate of the Meter):

When the filling-level indicator (1) is opened by turning the sealing screw (2) with Plastic Meters (or stop cock (2) with Stainless Steel Meters), the rising pipe of the level indicator is connected to the packing liquid in the gas meter housing in accordance with the communicating pipes principle. When the level in the gas meter housing rises as a result of topping-up with packing liquid, the level in the level indicator rises in the same way. The correct packing liquid level is reached when the surface of the liquid column in the level indicator is flush with the upper edge of the level indicator (3) and forms neither a dome nor an indent (see middle picture below).
 



The liquid column can be read off (if water is used as the packing liquid) more easily by reducing the surface tension by adding a drop of detergent. If too much packing liquid has been added, it comes over the level indicator causing the level to adjust itself to a certain extent. Any resulting liquid dome at the upper edge of the level indicator must, however, be remedied by draining off liquid via the drainage nozzles.

A small tip for checking the packing liquid level following an extended downtime of the gas meter: Following an extended downtime, the liquid in the level indicator is mostly evaporated, whereas it is not in the inside of the (closed) housing. If the level indicator's screw plug is now opened, the packing liquid flows out of the housing into the level indicator. Even if the packing liquid level was previously correct inside the housing, packing liquid must now be added and the level re-adjusted. This can be avoided by filling the level indicator with packing liquid before the screw plug is opened (neither dome nor indent). If the level does not change after the screw plug is opened, the packing liquid level was and still is correct.

2.5. After filling and adjustment of the packing liquid

• TG 01
  Replace the screwed cap on the outer end of the sloping tube of the HPLI. Close the filling nozzle by turning the sealing screws clockwise.
• TG 05 – TG 50
  Close the filling-level indicator and filling nozzle by turning the respective sealing screws clockwise.
• When the Meter is equipped with the HPLI (standard with the TG01)
  When closed, the HPLI can indicate a slightly lower filling level than it did after correct filling of the Meter. This can also occur during operation. This is system-related and does not indicate any error.. The given correct filling level will only be indicated when the Meter is not in operation and simultaneously, when the HPLI is open and not connected to the gas supply so that it is pressure-free.

2.6. Grounding of Gas Meters made out of electrically conductive material (PE-el)

Gas Meters with a casing and/or measuring drum made out of electrically conductive material (PE-el) must be grounded in order to discharge a potential static charge.

To do so the feeder clamp at a flange screw of the meter’s rear plate must be connected to ground (earth).

2.7. Connection of gas pipe

Connect the gas pipe to the inlet nozzle marked "gas-inlet" at the rear plate. Allow the meter to perform one or two revolutions in order to remove any possible air bubbles within the measuring drum. Then disconnect the gas pipe again and repeat the steps in paragraphs 2.3 and 2.4.

2.8. Moving of the filled meter

If the Gas Meter has to be moved after having been filled (for example carried into another room), it must be kept in a horizontal position. This is to avoid Packing Liquid getting into the Gas Inlet. If this occurs, the Gas Meter should be tipped 90° forwards (the dial face would then point to the floor). The Packing Liquid can then flow out of the Gas Inlet again (and back into the Meter).

Subject to alterations