The MilliGascounters (MGC) are designed for the volumetric measurement of the smallest amounts of gas with ultra-low flow rates. They are suitable for measurement of all inert, slightly corrosive gases such as biogas and aggressive gases as well as for volumetric leak detection.
RITTER MilliGascounters (1) (MGC) are designed for the volumetric measurement of the smallest amounts of gas with ultra-low flow rates. They are suitable for measurement of all inert, slightly corrosive gases such as biogas (PMMA model) and aggressive gases (PVDF model). Furthermore, MilliGascounters can be used for volumetric leak detection. (1) Developed at the University of Applied Sciences Hamburg, Prof. Dr. Paul A. Scherer
The gas to be measured flows in via the gas inlet nozzle (3), through the micro capillary tube (9) located at the base of the MilliGascounter and up into the liquid casing which is filled with a packing liquid (12). The gas rises as small gas bubbles through the packing liquid, up and into the measurement cell (13). The meas- urement cell consists of two measuring chambers, which are filled alternatingly by the rising gas bubbles. When a measuring chamber is filled, the buoy- ancy of the filled chamber causes the measurement cell to abruptly tip over into such a position that the second measuring chamber begins to fill and the first empties. The measurement of gas volume therefore occurs in discrete steps by counting the tilts of the measurement cell (13) with a resolution of approximately 3 ml (= content of one meas- uring chamber, please refer to par. 3.2. below). This “residual error” (= max. 3 ml) caused by the resolution should be taken into account when estimating/calculating the total meas- urement error. The tilting procedure of the measurement cell creates by the permanent magnet (11) on top of the cell and one of the two magnetic sensors (reed contacts) (10) a pulse which is registered by the counter unit (1). For external data logging (PC) the switching pulses of the second reed contact can be obtained via the signal output socket (2). (Please refer to par. 4.3 “Signal Output”). The measured gas exits through the gas outlet nozzle (4).
The minimum flow rate is theoretically zero ltr/h as there are no mechanical limitations with the MilliGascounter which would define a minimum flow. However, at such micro flow rates there are external influences becoming evident: temperature and pressure variation, tightness of the tube connection, permeability of the gas inlet hose. Therefore, the minimum flow rate was defined as 1 ml/h. The maximum flow rate is 1.0 ltr/h.
Because of the physical measurement principle, the measurement error is dependent on the flow rate and it rates ±3 % across the full flow rate range. Each MGC is individually calibrated at the standard flow rate of 0.5 ltr/h so that the measurement error is approx. 0% at this flow rate. At minimum flow rate the measurement error is approximately +3 %, at maximum flow rate approximately -3 %. The »RIGAMO« software (available as accessory) provides an algorithm which automatically recalculates the actual measurement data into the real volume at the respective actual flow rate on the basis of the calibration curve. The remaining error is smaller than ±1% across the full flow rate range.
The volume of the measured gas is displayed on the electronic digital display located on top of the MGC casing. Additionally a floating reed contact can be used as a signal output.
For data acquisition of gas volume and flow rate the Windows software »RIGAMO« is available. The data of up to 24 Ritter gas meters can be transmitted to the USB port of a PC.
The MGCs are available in the following casing/measurement cell materials:
