Task

The state volume converter UNIGAS PTZ converts the measured gas volume Vb of one gas meter at operation condition into m³ dry gas from standard condition pn = 1,01325 bar and Tn = 273,15 K.
The compressibility is considered as fixed value or according to the chart pressure stored in the calculator and temperature dependent.

Operating principle

The operation volume gas meter transmits impulses proportional to the measured flow to the processor of the UNIGAS PTZ Compact by means of a low frequency impulse converter mounted in or at the gas meter. The processor receives the values of the operation pressure and temperature from the sensors, which are either installed directly at the gas meter or at the piping.

Scope of delivery

UNIGAS PTZ Compact consists of the micro-processor controlled computing device, the pressure and the temperature sensors and an optimised 3-way test cock. The computing device can be mounted directly onto the gas meter or separately and is certified for use in hazardous aereas according to EEX ib IIC T5.

Pressure ranges

P_abs= 0,9 bar to 6,0 bar with official calibration "national"
P_abs= 4,0 bar to 10,0 bar with official calibration "national"

Temperature ranges

Gas temperatures -10°C to 40°C
Ambient temperature -10°C to 40°C
Storage temperatures -20°C to 50°C

Gas types

Natural gas acc. to DVGW-worksheet G 260, technical gases.

Retrievable data

Concerning the operation condition the UNIGAS PTZ Compact indicates the actual volume at standard condition via the LCD-display. By depression of key, the following values can be retrieved in addition:

• operation cubic meter V_b
• gas temperature  in °C
• operation pressure pabs in bar
• condition indicator Z
• fault codes
• battery consumption  in mAh
• operating hours
• fault register for  V_n
• fault register for  V_b
• compressibility factor  K
• remote data transfer on request

Accuracy

Total errors of measurement (reproducibility, hysteresis, room temperature) within ± 0.5 % from measured value.

Impulse output

A standard m3 impulse output with pulse times of 10 ms, 30 ms, 40 ms or 100 ms is programmable. Furthermore, an actual m3-impulse output or a fault alarm output is also programmable. A data interface RS 232 is also available.