The CNPS-ML11 type drilling fluid volume sensor is an ultrasonic liquid level sensor which combines the sensing technology and the electrical signal processing. It is used to monitor the change of the volume of the drilling fluid.
1 Working principle
The CNPS-ML11 type drilling fluid volume sensor is composed of an ultrasonic transmitter, a receiving device and a transmitter. The ultrasonic wave emitted by the ultrasonic transmitting device is reflected by the surface of the object, and then is received by the receiving device. The transmitter converts the signal generated during ultrasonic emission and reception to the standard current signal.
The probe of the sensor sends out a series of ultrasonic pulses, while the ultrasonic pulse returns after receiving the liquid level, and is received by the sensor. The filtering device in the sensor can distinguish true echoes from the liquid surface from various false echoes from sound waves, wave noise and rotating agitator blade noise. The pulse wave is converted from the time of temperature compensation to the time used by the emission to the liquid surface and then back to the sensor.
2 Technical indicators
Power: +15V ~ 30V DC (recommended +24V DC)
Measurement range: 0.25 m to 5 m
Output current: 4 ~ 20mA
Measurement accuracy: + 0.5%FS
Environmental conditions: working temperature -40 C ~ +60 C
Relative humidity: 5 ~ 95%RH
3.1 Sensor installation
The ultrasonic level sensor should be installed on the sensor mounting rack.
When installing, sound wave propagation route should be no obstacle and perpendicular to the liquid surface. Be careful not to cross the filling, pipeline, weld, ladders, etc., and not to the wall.
During installation, the distance between the sensor end and the highest liquid level should be kept at least 25cm.
3.2 Sensor connection
Open the seal box cover sensor terminal, “+” +24V “-” power supply terminal connection signal.
（1）After the electricity, enter the automatic operation mode;；
（2）At the same time press 20mA20and 4mA 4 Touch key；
（3）When the display of C4 represents the initialization of the 4mA calibration；
（4）Wait 3 seconds ,it will show the value that has been saved，And then press 20mA20or4mA 4 ，The value required for the up and down movement selection（=Mud pool height + The distance between the end of the sensor and the top of the mud pool），The loosen bond；
（5）After waiting for 6 seconds, enter the auto run mode；
（6）At the same time press 20mA20和4mA 4 key two times，Display sequence C4-C20, release the key；
（7）When C20 is displayed, 20mA calibration initialization is indicated；
（8）Wait for the stored value to appear and press 20mA20和4mA 4 key，Move up and down to select the desired value（=The distance from the end of the sensor to the top of the mud pool），then release the key；
（9）Repeat step 5；
(10)Press simultaneously 20mA20 and 4mA 4 key three times，display order：C4→C20→bL，then release the key；
(11)Initial calibration for blind zone values when bL is displayed；
(12)Repeat step 4, but select the desired value > 25mm；
(13)Repeat step 5；
(14)Press simultaneously 20mA20 and 4mA 4 key four times，display order：C4→C20→bL→SP，then release the key；
(15)When the SP is displayed, the calibration initialization indicating the response speed value；
(16)Repeat step 4, but generally select the desired value of 2；
(17)Repeat step 5；
(18)Press simultaneously 20mA20and 4mA 4 key five times，display order:C4→C20→bL→SP→FLS，then release the key；
(19)When FLS is displayed, it indicates that the fault protection calibration initialization；
（20）Repeat step 4 to select the desired value, usually 1 or 2；
（21）Repeat the fifth step；
（22）Press simultaneously 20mA20and 4mA 4 key five times，display order：C4→C20→bL→SP→FLS→FSE，then release the key；
（23）Repeat step 4 to initialize the calibration fail-safe duration；
（24）Repeat step 5 to set the value you need (any value can be selected from 0 to 15)；
Ultrasonic sensor calibration operation has been completed through the above series of steps.
（1）C4 means 4mA；
（2）C20 means 20 mA；
（3）BL：,eans Dead zone, generally set> 25cm；
（4）SP：The response speed refers to the speed of the reflected wave feedback to the emitted wave. There are 4 options in total. Normally, it is set to 2 (distinguishing the agitator interference)；
（5）FLS：Failure protection value, loss of echo or misoperation, there are 3 choices of output modes；
（6）UN：Unit selection: There are 2 options, 1 is metric, 2 is imperial；
（7）FSE：Fail-safe maintenance time, total (0~15 minutes) selection, optional one。
5 Maintenance and maintenance
Pay attention to keep clean, no water vapor and oil can enter the operation panel, signal cable inlet should pay attention to seal, prevent water and oil from entering.