HXXO20100625004602PEC4 3000

Table of Contents

RITTER Bellows-type Gas Meters


RITTER Bellows-type Gas Meters are applicable for measuring the volume of flowing inert and dry gases and are particularly effective at high gas flows. Please note that gases containing aggressive components or water vapour may reduce the life span of bellows-type gas meters, if the casing of the measuring unit (tinplate), the valve/control elements (polyamide) or the bellows (Perbunan®) should be attacked. Further details on the materials that may come into contact with gases can be found under »Materials«.

The desired measurement range can be selected from among 6 magnitudes (types) extending together as a whole from 40 ltr/h to 160 m3/h at a gas temperature ranging from -20 °C to +50 °C. The solidly soldered casing on the standard model is designed to withstand a maximum overpressure of 50 mbar (BG 40/100: 0.5 bar).


The major advantage and the superiority of volumetric gas meters (like bellows-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 that the volume is directly measured by the principle of displacement. That means that the condition and the composition of the gas has no influence on the measurement accuracy.

The measurement principle and the design of the measuring unit enables a measuring accuracy of ±2%.

Correcting factors which take into account gas type, temperature, humidity etc are therefore not necessary(1). It should be noted that with other, non-volumetric measurement processes, the measurement accuracy given for that process can only be achieved if the correcting factors for the immediate condition of the gas are exactly known. The RITTER Bellows-type Gas Meters need no maintenance and no set-up prior to the measurement. They are easy to carry, don’t need a power supply (unless equipped with option »Pulse Generator«) and can therefore used »in the field« as well without problems.

(1) The measurement of temperature and pressure is necessary, if the measured and indicated actual volume of gas must be recalculated into the norm volume (as with any measurement of gas volume).

Performance Data

Type Flow Rate
Flow Rate
Flow Rate
(ltr/h) (1)
Readout Indication
(ltr) (2)
Readout Indication
(ltr) (2)
Maximum gas
inlet pressure
BG 4 40 6,000 3,000 0.1 99,999,999    300
BG 6 60 10,000 5,000 0.2 99,999,999    300
BG 10 100 16,000 10,000 0.5 999,999,990    50
BG 16 160 25,000 15,000 0.4 999,999,990    50
BG 40 400 65,000 39,000 0.4 999,999,990    500
BG 100 1,000 160,000 95,000 0.4 999,999,990    500

(1) The calibration is performed at standard flow and 20 °C (68 °F)
(2) Minimum dial division

Measuring accuracy: +/- 2% at standard flow and 20 °C (exact value is stated in individual Calibration Certificate)

Temperature range: -20 °C to +50 °C

No reverse flow direction possible!

Measurement Principle

The measurement of RITTER Bellows-type Gas Meters works on the principle of displacement. The Gas Meters contain a twin-chamber measuring unit with a flexible bellow within each chamber. Thus, a compulsory measurement of the gas flow is possible when these chambers are periodically filled and emptied. The design of the measuring chamber is such that the measuring volume per cycle of the bellows is constant. Because of the measurement principle the actual volume is measured. The movement of the bellows is caused by the pressure difference between inlet and the outlet of the meter. The periodical filling is controlled by means of two sliding valves. The oscillating movement is transformed into a rotational one and is mechanically transmitted to the counter through a magnetic coupling.
BG Measurement Principle
  1. Outer casing of the meter: Material: Zinc-coated steel sheet (soldered) with outside also lacquered.
  2. Casing of the identical twin chambers of the Meter. Material: Tinplate
  3. Non-flexible part of membrane. Material: Tinplate sheets. Flexible part of membrane.
  4. Material: Textile-reinforced nitrile rubber (Perbunan).
  5. Gas entry to the chamber.
  6. Gas outlet

Standard Equipment

  • Twin-Chamber Measuring Unit
  • 8 or 9-digit Totalizing Roller Counter
  • Large One-needle Dial
  • Magnetic Coupling (between measuring drum and counting mechanism)
  • Gas Pipe Connection (inch thread)


  • Casing:
    • BG 4 – BG 16: Zinc-coated steel sheet (soldered) with outside also lacquered
    • BG 40 – BG 100: Powder-coated steel sheet with outside also lacquered
  • Measuring unit: Tinplate
  • Bellows (within measuring unit): Textile-reinforced Perbunan
  • Rod linkage: BG 4: Polyamide; all others: Polyamide/brass
  • Slide gate: Bakelite

Built-in Options

  • LCD Display, resettable, 8-digit (replaces Totalizing Roller Counter)
  • Pulse Generator, standard or Ex-proof version (for connecting Electronic Display Unit/Computer)

Accessories (external)