PDF《Compact Gas Volume Corrector》

Compact Gas Volume Corrector System EC

900 Serving the Gas Industry Worldwide PRODUCT INFORMATION COMPACT GAS VOLUME CORRECTOR SYSTEM EC

900 2 Method of operation, EC

900 system and ?elds of application Method of operation Irrespective of pressure and temperature, a gas meter measures only the gas volume ?owing through it, i.

e. what is called volume at measurement conditions. Since gas can be compressed, the quantity of gas which has actually ?owed through the gas meter still has to be calculated from the measured volume at measurement conditions (correction). As a measure for this quantity of gas, what is called volume at base conditions (related to the temperature at base conditions of 0°C and the pressure at base conditions of 1.01325 bar) is used. The EC

900 compact gas volume corrector carries out this conversion on the basis of the equation of state for ideal gases. Since this equation alone does not meet all the requirements for high-precision gas measurements, it is also necessary to take account of the characteristics of the real gas by using a correction factor, i.e. the K coe?- cient. The EC

900 system The EC

900 system is mainly characterized by its ver- satility and its extensive communication functions. The device can basically be ?tted with a ?xed-line or radio modem. An external communication module is available for applications where a modem cannot be installed for reasons of explosion protection (Ex zone 1). The EC

900 system comprises four di?erent types of devices which are classi?ed according to their ATEX ap- proval (equipment for Ex zone

1 or 2) and type of power supply. The major di?erences of the four types are listed in the table below. Fields of application The EC

900 compact gas volume corrector is particularly suitable for use in small and medium metering stations where rotary piston meters or turbine meters are used for metering and no electrical equipment room with con- trol cabinets is available. Such stations are often opera- ted at points where gas is delivered to smaller municipal services or to commercial gas consumers. The EC

900 can be installed and started up easily. It can be installed either directly on the gas meter, the wall or a stand or pipe. If it is ordered together with an RMG rotary displacement meter or turbine meter, the EC

900 can be delivered readily installed and parameterized. The battery-powered version can process LF pulses of up to

10 Hz, while mains-operated devices can also be operated with HF pulses and thus enable the ?ow rate to be calculated. An encoder index can be connected to both versions. Pressure and temperature transmitters The pressure transmitter is ?tted into the casing of the EC

900 as standard. There are

5 operating pressure ranges of up to

40 bar available. Connection is made via an M12 x 1.5 joint for Ermeto 6L pipes. A PT

1000 with 4-wire connection is used as a tempera- ture transmitter, with a G? joint and variable face-to- face dimension (G? and G? connections as options). Di?erences of the

4 device versions Approval for use in Ex zones

1 &

2 Approval for use in Ex zone

2 EC

911 Powered by an internal battery Volume pulses: reed or Wiegand EC

921 Powered by

2 internal batteries Volume pulses: reed or Wiegand Internal modem EC

912 Externally powered &

emergency battery Volume pulses: reed, NAMUR or Wiegand Plus external communication module with - modem - interfaces (IR, RS 232, RS

422 / RS

485 / Ethernet) -

4 analog outputs - power pack EC

922 Externally supplied &