What is our SRM900 series magnetostrictive liquid level sensor used for?

Problems with traditional measurement methods

  In the petroleum and petrochemical refined oil circulation industry, most of the measurement of the oil content of the oil tank uses artificial climbing the tank and casting a ruler to measure. Use a metric steel tape measure with a heavy hammer or a scale with a scale to measure, manually record the reading, manually look up the table and convert it, and finally get the oil quantity data. This measurement method not only has high labor intensity, but also has unsafe factors, and cannot guarantee accuracy. In some places, capacitive / diffused silicon pressure level gauges are used for measurement. Due to the serious zero drift of this type of sensor, the measurement deviation is large, and the long-term working stability is poor, which is not welcomed by users. There are also places where isobaric membrane level gauges or mechanical float level gauges are used. However, because the membrane type liquid level gauge is greatly affected by temperature, and there is a problem of air leakage, the mechanical float liquid level gauge often appears to be stuck in the steel belt, so it has not been widely used.
 

Solution

  The high-tech magnetostrictive liquid level gauge is used for the liquid level measurement of various storage tanks. This type of liquid level instrument has the characteristics of high accuracy, strong environmental adaptability, and easy installation. Therefore, it is widely used in the field of liquid level measurement in petroleum, chemical industry, etc., and gradually replaces other traditional sensors and becomes a fine product in liquid level measurement.

Working principle

  The structural part of the magnetostrictive liquid level sensor is composed of a stainless steel tube (rod), a magnetostrictive wire (waveguide wire), a movable float (with a permanent magnet inside), and the like. 

  When the sensor is operating, the circuit portion will excite a pulsed current on the waveguide wire that will generate a pulsed electromagnetic field around the waveguide wire as it propagates along the waveguide wire. A float is arranged outside the sensor rod, and the float can move up and down along the rod as the liquid level changes. There is a set of permanent magnetic rings inside the float. When the pulsed current magnetic field meets the magnetic ring magnetic field generated by the float, the magnetic field around the float changes so that the waveguide wire made of magnetostrictive material generates a torsional wave pulse at the position where the float is located. This pulse is along a fixed speed. The waveguide wire is transmitted back and detected by the detection mechanism. By measuring the time difference between the pulse current and the torsional wave, the position of the float, that is, the position of the liquid surface, can be accurately determined.

SRM900 series's main technical performance indexes

a) Range: hard rod: 150 mm ~ 7000 mm, soft rod: up to 16000 mm;
b) Output form: 4-20mA; 0-5V; 0-10V; ± 5V; ± 10V; RS-485
c) Linear error: better than ± 0.05% FS; the error of sensor with range less than 300 m m is less than 150 μ M d) Repeatability: better than ± 0.002% FS
e) Output temperature drift: 50ppm / °C;
f) Product power consumption: ≤ 50mA;
g) Output ripple: ≤ 20mV;
h) With load capacity: 4-20mA output: with load capacity ≤ 500 Ω;
0-5V, 0-10V output: minimum controller load ≥ 5K Ω;
g) Power supply: 24V ± 2.4V. DC

Various installation methods

·Threaded installation

  As shown in the figure, when the product is installed vertically, the installation slope shall not be more than 5 degrees; when installing the floating ball, the hemispheres marked with no (upper) shall be above the liquid level; there is a dead zone at both ends of the measuring rod; when the locking ring is fixed, the lower end shall be flush with the bottom end of the rod.

  This method is suitable for most liquid tank measurement. The connecting flange provided by the manufacturer or the flange specially customized by the user can be selected, and the installation thread of the liquid level sensor can be screwed directly into the flange.

 

·Installing with an active connector

  This method is suitable for measuring height-adjustable can open and sealed cans.

·Positioning ring installation

  The sensor rod touches the bottom of the tank, and the positioning ring of the electronic warehouse is used to prevent the sensor from swinging. The sensor electronic warehouse and the outgoing cable are in the oil tank. Note:
h = tank height

H = h + riser height
D = Φ100mm Standpipe height ≥ 300mm

·Suspended installation

The sensor is hung under the flange of the tank mouth, and the measuring rod is kept at a certain distance from the bottom of the tank (2~5mm). The positioning ring of the electronic warehouse is used to prevent the sensor from swinging. The sensor electronic warehouse and the outgoing cable are in the oil tank.
Note:

h = tank height
H = h + riser height D=Φ100mm
Standpipe height ≥300mm