Overview of how drum meters work
Drum meters/standard sampler
Drum meters are purely mechanical devices where the liquid to be measured drives the mechanism. It must be ensured that there is no counter-pressure on the outlet, i.e. a backpressure of the liquid must not occur in the meter.
The measuring unit, the rotating drum, is divided into three chambers.
Filling-up of the bottom chamber and overflowing of the liquid into the next chamber displaces the center of gravity of the filling, and a turning movement results. The drum is rotated by one third of its circumference, i.e. the next chamber is swung down and then filled whilst the previous chamber is emptied through the outlet.
The number of times the drum is moved round is transmitted from the axis of the drum to a single-pointer dial with a 5-digit non-resettable drum-type counter via a magnetic coupling. The quantity determined from the number of drum rotations is directly displayed in liters.
SITRANS A ethyl alcohol meters
The ethyl alcohol meters work by the same principle as the drum meters. In other words, the total quantity of spirits flowing through the drum is measured. Since the quantity of pure alcohol (ethyl alcohol) present in the spirits must be known for taxing purposes, the spirits are passed prior to the quantity measurement through a test setup consisting of temperature measuring equipment with a Pt 1000 sensor and equipment for measuring the density.
Pulses proportional to the quantity are output by means of a double pulser coupled to the drum.
The input signals for quantity, temperature and density are compared in a computer with the defined values of the OIML alcohol table.
Following displays are output on two non-resettable electromechanical pulse counters in the computer:
- Quantitiy of mixed alcohol/water in liters
- Quantity of alcohol in liters
The density and temperature of the liquid can be read continuously on a further display.
Connections are available for a printer, a remote indicator and an RS 232 interface.