Beskrivelse
Produsents beskrivelse av ULLC2001:
The Theory of Operation – Surface Acoustic Waves (SAW) were quantitatively described by Lord Rayleigh in 1885, when he showed theoretically that waves can be propagated over the plane boundary of an elastic half space and a vacuum or a sufficiently rarefied medium, (e.g. air), where the amplitude of the wave decay rapidly with depth. They are of course, mechanical, (acoustic) waves rather than electromagnetic. The destructive force of an earthquake propagates in this manner. The Comparator indicates the Surface Acoustic Wave via its 16 Bar Graph display, by sliding the transducer from below level up to the calculated level position.
How the ULCC2001 (M) Comparator works
The Transducer assembly transmits pulses of acoustic energy. The reverberation caused is dependent on the nature of the container (steel, glass, etc.) and the nature of the fluid, (liquid gas and air), contained within it.
Due to the way that the transducer couples with the surface of the container, most of the power tends to be transmitted at the centre of contact, allowing a fairly precise measure of the point at which the acoustic energy has been launched.
Due to the variable nature of the reverberation, the “tune” control allows us to reduce or increase the amount of received energy in order to get it within the range of sensitivity of the instrument. The returned signal is then rectified and smoothed to give a measure of the signal level.
Using the Comparator to find Extinguisher Gas Levels
The transducer is placed against the cylinder body, 120mm below the calculated liquid gas level, where the extinguisher fill should be certain (normally mathematically calculated). While retaining the transducer at this point the Comparators ultrasonic level is set to around two or three divisions / bars-■■■, by use of the 0-10 Tune Control. This gives a reference level against which the signal at the gas level / air interface is compared.
By slowly sliding the transducer up the cylinder body, we will arrive at the gas level / air interface. At which point the signal will rise sharply, this is visible on the Comparator usually as all 16 divisions / bars-■■■■■■■■■■■■■■■■ and is due to the enhanced propagation of the Surface Acoustic Wave (SAW), across the liquid gas.
The unit also incorporates an ambient temperature sensor; the temperature is indicated on the units display, this is useful for making temperature adjustments to the mathematically calculated level.
Optional Comparator ancillary items for the Robo Transducer: A mechanical Transducer system is also available if more precision is required. The Robo Transducer eliminates any possible human influence on the ultrasonic signals transmitted and received by the Comparator. Definition between signals and the interpretation of the SAW effect signal is made extremely clear. It is then simple to pin point the liquid level repeatedly.
To use the Robo Transducer simply mark the cylinder with the calculate level, and apply a film of Ultrasonic Gel over the level mark. Fit the Robo Transducer lining it up with the Calculated Liquid Level and its transducer at the bottom which would be 4”/100mm below level. Tune the Comparator to suit the cylinder and then simply slide the Transducer up the rails until the SAW effect signal is clearly indicated.
