COMMON S.A Gas Meters (Quantometer, Turbine & Rotary)

The turbine gas meter measures the quantity of gas basing on the flow principle. The gas flows through an integrated flow conditioner, which distributes the flow proportionally in the annular slot and guides it to the turbine wheel. The wheel is driven by the gas flow, and the angular velocity of the rotation is proportional to the gas flow rate. The energy consumption, perceived as pressure loss, is reduced to absolute feasible minimum due to the application of the flow conditioner, highest precision ball barings, most accurate tolerances of all measuring parts and their proper alignement. The rotary motion of the turbine wheel is transferred mechanically by gear wheels, and the incorporated gas tight and hermetic magnetic coupling, to the index unit, which is mounted on the top of the body, and shows the operating volume on the totalizer.

The basic components of the CGT-02 turbine gas meter are as follows:

• Pressure resistant meter body
• Inlet flow conditioner
• Measuring cartridge with the turbine wheel
• Magnetic coupling as the transferring element between measuring cartridge and the index
• Index
• Lubricating system (some meters are provided with self lubricating bearings)

The meters are mainly used for measurements of combustible and inert gases.

Figure 1. Measurement error typical curve at low pressure (average 1 bara) – green curve and at high pressure (over 5 bara) – blue curve

Table 1

Table 2: Physical properties of most popular gases that may be measured with the CGT turbine gas meters – density at 101,325 kPa and at 20°C

PRESSURE AND TEMPERATURE OUTPUTS

The operating pressure (reference pressure) can be taken from the pressure taps, marked pr, located on both sides of the meter body. The meters DN100 and larger can be optionally equipped with two temperature taps for the measurement of the gas temperature.

PULSE SENSORS

The mechanical index unit indicates the actual volume of the measured gas at operating temperature and operating pressure. It can be rotated axially by 350° in order to facilitate the readings and enable easier connection of pulse sensor plugs. The index unit is provided with one low frequency reed contact pulse transmitter (LFK), as a standard. On request the index may be equipped with:

• LFI – low frequency inductive pulse sensor (NAMUR)
• HFI – high frequency inductive pulse sensor (NAMUR)

The CGT-02 turbine gas meters may be provided with up to 10 pulse sensors for DN100 – DN400 and up to 8 pulse sensors for DN50 – DN80

• LFK – low frequency reed contact pulse sensor LFK1, LFK2
• LFI – low frequency inductive pulse sensor LFI1, LFI2
• HF – inductive pulse sensor:
  
  • HF1, HF2 – in the index head
  • HF3, HF4 – over the turbine wheel
  • HF5, HF6 – over the reference wheel
• AFK – anti-fraud reed contact AFK

The turbine wheel is made of aluminium, as a standard. This allows to provide each turbine gas meters with HF inductive pulse sensors.

DIMENSIONS AND WEIGHTS

* size E is valid for meters PN16, PN20 and ANSI 150, size F is valid for meters PN50, PN64, PN110, ANSI300 and ANSI600

INSTALLATION AND OPERATION RECOMMENDATIONS

• Meters should be shipped in their original package to the place of installation.
• Meters have to be handled with care and protected against falls, direct infl uence of rain, snow or high humidity.
• The measured gas should be clean, dry and free from solid impurities. It is recommended that the upstream pipe installation is to be equipped with a filter (10 micron).
• Prior to putting into operation in new installations, it is recommended to install a temporary cone sieve.
• Prior to installation the upstream and downstream pipe fl anges should be aligned properly.
• Flange gaskets are to be installed so as not to disturb the gas flow.
• The gas flow should be in accordance with the arrow placed on the meter body.
• The piping should be executed so as to avoid unnecessary stresses acting on the meter.
• When used outdoors the meter should be protected against direct weather infl uence.
• When starting the gas flow through the installation, the valves should be opened slowly to ensure a gradual increase of pressure.

ATTENTION! If valves are opened abruptly or pressure increase takes place in a short time it may happen that the measurement cartridge or the turbine wheel get damaged.

ALWAYS REMEMBER TO START UP THE METERS IN A PROPER WAY!

The research and development program is being continued by COMMON S.A. Technical specifications and construction may change due to improvements.