Liquid Level Meter/Sensor/Transducer/Transmitter

Time-of-flight method
The sensor of the meter pulses in the direction of the product surface. There, they
are reflected back and received by the sensor. The meter measures the time t between pulse transmission and reception. The meter uses the time t (and the velocity of sound c) to calculate the distance D between the sensor membrane and the product surface:
D = c •t/2
As the device knows the empty distance H from a user entry, it can calculate the level as follows:
L = H - D
An integrated temperature sensor compensates for changes in the velocity of sound caused by temperature changes.
Calibration
Enter the empty distance H and the span F to calibrate the device.
Blanking distance
Span F may not extend into the blanking distance B. Level echos from the blanking distance cannot be evaluated due to the transient characteristics of the sensor.

Product features

The standard remote ultrasonic level meter.
   Standard series has 2 relays (high and low);
   The cable between the probe and the host can be 20m at most.

The enhanced remote ultrasonic level meter.
    Enhanced series can have 2 probes to measure 2 point’s level;

       Enhanced series can provide 6 relays at most;
    Enhanced series can provide RS485 serial communication;
    The cable between the probe and the host can be 1000m at most;
    Enhanced series can be configured by “remote control”.

The difference-level measurements.
    Difference-level series can provide two pair 4-20mA output or one 4-20mA and one RS485 output;
    The cable between the probe and the host can be 1000m at most;
     Difference-level series can be configured by “remote control”.

How to choose a proper ultrasonic level meter
The structure
The compact version: the host and the probe are integrated;
The remote version: the host and the probe are separated.
The wire
Two-wire system:
It is standard transmitter which power supply （only DC24v）and signal output （DC4-20mA）use same current loop; Two wires are enough.
Three-wire system:
Three-system is four-system in fact; either the power supply or (4-20mA) signal output uses one separate current loop. When negative is with same ground reference, then three wires are enough. Its advantage is strong transmitting power.
Four-wire system:
Either the power supply or signal output (4-20mA) uses one separate current loop. Its advantage is strong transmitting power and provides high and low relay output.

Measuring range
Select model number according to actual range. Select model number with bigger range if medium level fluctuating strongly. The range of solid level is generally one-half to two –third of that of liquid.

Power supply
DC24V power supply：
For two-wire system, the power supply current should not be less than 30 mA. For three-wire system, the power supply current should not be less than 60 mA.
For four-wire system, the power supply current should not be less than 80 mA.
AC220V power supply:
Only for four-wire system, the power supply current should not be less than 50 mA.

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