(1) The calibration is performed at standard flow and 20 °C (68 °F)
(2) Minimum dial division
The maximum gas inlet overpressure is dependent on the gas meter type and casing material:
With plastic casings TG05 – TG5: Standard version 50 mbar
With plastic casings TG10 – TG50: 50 mbar
With stainless steel casings: 0.5 to 40 bar
Measuring accuracy: ± 0.2% at standard flow rate (exact value is stated in individual Calibration Certificate) and approx. ± 0.5% across the entire measuring range.
RITTER Drum-type (wet-test) Gas Meters are universally applicable for measuring the volume of flowing gases and are particularly effective when measurements demand the highest precision.
The possibility of selecting the gas meter material from among 5 different excellent materials: Polyvinyl Chloride (PVC), Polypropylene (PP), Polyvinylide Fluoride (PVDF), PE-el (polyethylene electrically conductive) or refined stainless steel 1.4571 (316 Ti) enables the user individually to meet measurement requirements even in case of highly aggressive gases.
For rugged, industrial applications, robust models with a stainless steel casing and plastic drum (four different materials) are available.
The desired measurement range can be selected from among 8 sizes (types) extending as a whole from 1 Ltr/h to 18,000 Ltr/h at a gas temperature ranging from -10 °C to +80 °C. The solidly manufactured casing of the standard meters is designed to withstand a maximum overpressure of 50 mbar (plastic casings) or 500 mbar (stainless steel casings); meters for higher pressure ranges up to 40 bars are available.
The measurement of RITTER Drum-type Gas Meters works on the principle of displacement. The gas meters contain a revolving measuring mechanism (measuring drum) within a packing liquid (usual: water or low-viscosity oil). The measuring drum compulsorily measures volume by periodically filling and emptying four rigid measuring chambers.
Fastidious production methods and calibration enable a measuring accuracy of ± 0.2% at standard flow rate and approx. ± 0.5% across the entire measuring range.
The major advantage and the superiority of volumetric gas meters (like drum-type gas meters) over other measurement principles, which determine gas volume using secondary measurable variables such as speed, heat capacity, hot-wire resistance or similar, is the direct measurement of volume. That means that the condition and the composition of the gas have no influence on the measurement accuracy.
Correcting factors which take into account gas type, temperature, humidity etc are therefore not necessary. It should be noted that with other, non-volumetric measurements the accuracy given for that measurement can only be achieved if the correcting factors for the actual gas condition or gas mixture are exactly known.
The direct measurement of volume is the major advantage and the superiority of volumetric gas meters (like drum-type gas meters) over other measurement principles, which determine gas volume using secondary measurable variables such as speed, heat capacity, hot-wire resistance or similar. That means that the condition and the composition of the gas do not influence the measurement accuracy.
Correcting factors which take into account gas type, temperature, humidity etc are therefore not necessary. It should be noted that with other, non-volumetric measurements the accuracy given for that measurement can only be achieved if the correcting factors for the actual gas condition or gas mixture are exactly known.
The drum-type meters need no maintenance and no power supply (unless equipped with option »Pulse Generator).
Advantages of RITTER Drum-type Meters
1. Casing and Measuring Drum out of superior plastics
RITTER Drum-type Gas Meters are specifically designed for use with corrosive gases. They are made out of a selection of 4 superior plastics (PVC, PP, PVDF and electrically-conductive PE). A gas meter can therefore be selected which is completely resistant to the corrosive gases being measured. Stainless steel is not completely resistant to corrosive gases and will be damaged by them over time.
Even RITTER’s Gas Meters with a stainless steel casing have a measuring drum made out of one of these high quality thermoplastics. This is because the measuring drum is the most important part of the gas meter and also the most susceptible to the effects of corrosive gases.
2. Measuring Drum is welded – not soft soldered
Competitor meters have a stainless steel casing and a measuring drum that is also made out of stainless steel. Because the steel plates used to make these measuring drums have to be so thin, they can only be soft soldered together. Soft solder weldings are eaten away by aggressive gases very easily! So even when the stainless steel itself is fairly resistant to corrosive gases, the soft soldering is not. This can cause the measuring drum to completely fall apart when the soft soldering is eaten away.
The measuring drum parts in RITTER Gas Meters are welded together with exactly the same material that the drum is made out of. PVC drums are welded together with PVC rods; PP drums with PP rods, PVDF drums with PVDF rods and PE drums with PE rods. The welds in RITTER Gas Meters are therefore as corrosion-resistant as the material used to build the drums.
3. Casing and Measuring Drum resistant against Packing Liquid – if turned into an acid
All drum-type gas meters contain a Packing Liquid – usually water. If the measuring drum is stainless steel and is used to measure a gas which reacts with water to form an acidic solution, the acidic solution can eat through the part of the measuring drum sitting under the water-line. This occurs most rapidly in gas meters which are not used very often. RITTER Gas Meters do not have this problem.
4. No epoxy coating needed for measuring drums
Some gas meter manufacturers offer stainless steel measuring drums with epoxy coating. It is very difficult to apply the coating completely evenly on the drum surface, especially in the sharp corners of the drum (where the soft solder welds are). These are weak spots where corrosive gases can even more easily start to attack and destroy the drum material and soft solder welds.
5 .Magnetic Coupling instead of O-ring for drum axis
