The natural gas which is fed into gas regulator stations must usually be reduced by means of a pressure balance to a pressure of approx. 40 mbar. The pressure in the consumers’ mains is to be kept constant irrespective of the arising consumption quantity. Performance and functional safety of the fitted control valve are requirements for a good working supply. For this reason Höntzsch vortex sensors in Ex-design for velocity / volume flow measurement are installed in the gas regulator station in a large German town. The pipelines with a nominal diameter of DN 300 which are installed there have a gas flow of max. 3000 m³/h.

The principle of measurement for vortex flow sensors is based on vortices being shed when a flowing medium reaches an obstruction or strut. The vortex shedding frequency is a dimension for the flow velocity. The advantage of this principle of measurement - when measuring within the respective specifications - lies in the independence of density, pressure and temperature of the medium. The measuring result is always displayed directly and precisely without the use of any additional manipulation or conversion with the help of tables.

As the vortex flow sensors have no moving parts they have outstanding fatigue strength even in rough conditions. Even moisture in gases is of no disadvantage as long as condensation does not set in. At the same time they are robust, reliable and corrosion resistant. The measuring is almost inertia-free. A special advantage: impurities in gases in the form of solids do not impair measurement. The shedding of vortices generates a self-cleaning effect on the strut.

Höntzsch vortex sensors are used for detecting the volume flow of air, gas mixtures, natural gas, torch gas, etc. Their standard application is in the region from 0.5 m/s up to 40 m/s and they are designed for working termperatures from -25 °C to +180 °C. Compared to other measuring systems lower flow velocities can be measured and a greater turndown ratio can be obtained.

Due to the special design of the sensor head moist gas does not affect the measuring system in any way: even in subatmospheric pressure velocities from 0.5 m/s can be measured. Vortex flow sensors are TÜV qualification tested according to TA-Luft, 13th and 17th BImSchV and are also approved for use in potentially explosive areas.

The evaluation of the flow velocity or volume flow respectively is undertaken by transducers or systems instruments. In the case of additional measuring points multi-channel systems with display and keypad enable the free configuration of the parameter.

When the Höntzsch vortex flow sensors are being used for controlling the flow velocity of natural gas, the notation of the measurement signal by a recorder serves simultaneously to prepare statistics about the utilization of the regulator in use.