RU2469297C1 - Method and apparatus for calibrating turbidity sensors - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: method of calibrating turbidity sensors involves picking up the signal of the sensor depending on turbidity of the liquid passing through it. The sensor is placed in a closed loop with a uniform cross-section in which there is directed movement of liquid with constant speed which enables to form a uniform suspension of particles. The required concentration of particles and their fractional composition are provided by adding a weighted portion of particles of a given fraction to the liquid. The apparatus for calibrating turbidity sensors has a vessel with a liquid in which there is a mechanical drive with a control which provides it with movement and a turbidity sensor with a measuring system. The vessel is in form of a closed loop with a uniform cross-section in which there is a pump. A loading unit is mounted in the top part of the loop and the calibrated sensor is placed in the descending branch of the loop.

EFFECT: high accuracy and reliability of calibration.

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Description

The present invention relates to measuring technique, to the technique of conducting marine measurements and can be used to calibrate turbidity sensors (background transparency) of the liquid.

A known method for calibrating turbidity sensors using a reference turbidity sensor (1). This method has the following disadvantages.

1. To carry out the calibration of the sensors, it is necessary to create and maintain a reference turbidity sensor with higher accuracy than the calibrated sensor.

2. Due to the disturbances introduced by the sensors in the fluid flow, as well as the difficulty of obtaining a uniform fluid flow, it is impossible to create an identical density of suspended particles of the calibrated and reference sensors with high accuracy. In the existing calibration device, it is difficult to ensure a uniform field of fluid flow rates in the tank. The unevenness of the velocity field of the fluid flow can lead to stratification of the suspension and sedimentation of the heaviest particles in places with a low flow velocity.

The aim of the present invention is to improve the accuracy and reliability of calibration. The goal in the method is achieved by the fact that the sensor is placed in a closed loop of constant cross-section, in which directed motion of the fluid is created at a constant speed, ensuring a uniform suspension of particles, while the required concentration of particles and their fractional composition is provided by adding weighted portions of particles to the fluid given fractions.

The goal in the device is achieved by the fact that the vessel is made in the form of a closed loop of constant cross section, into which the pump is connected, a loading unit is fixed in the upper part of the circuit, and the calibrated sensor is placed in the descending branch of the circuit.

Improving calibration accuracy is achieved using standards of weight and volume. Methods of measuring weight and volume have a higher accuracy of measurements, which allows to increase the accuracy of calibration. A predetermined suspension concentration is created by adding the required suspension mass, determined by weighing, and bringing the total volume (liquid plus suspension) to the volume of the closed loop. Creating an equal fluid velocity throughout the volume is achieved by using a closed loop with a constant cross section.

The uniformity of the concentration of the suspension is ensured by the movement of fluid in the circuit at a speed known to exceed the speed necessary to create the suspension, and the location of the calibrated sensor in the area of fluid movement down.

Possibility of implementation

Figure 1 shows a calibration device that implements the proposed method. It contains a calibrated sensor - 1, a closed loop of constant cross section - 2, a suspension loading unit - 3, a pump - 4, a pump drive motor - 5, an engine speed regulator - 6.

The device operates as follows. Through the loading device 3, the suspended suspended fractions are loaded and the circuit is filled with liquid to a fixed volume. The fluid in the circuit is driven by the pump 4. The direction of fluid flow in the circuit is shown by arrows 2. The speed of the fluid is set using the regulator 6, which controls the speed of the pump motor 5. The calibrated sensor is installed in the circuit in the section of movement of the suspension down to avoid separation of the suspension . The increase in suspension concentration during the calibration process is carried out by adding new portions of the suspension and removing excess fluid. The uniformity of the suspension is created due to the movement of the liquid at a speed obviously exceeding the speed necessary to create the suspension. The necessary concentration of particles and their fractional composition are created by mixing suspended particles fractions with a liquid. The total volume of the mixture is equal to the volume of the circuit of the calibration device.

Sources of information used in the preparation of the application

1. Dynamic processes of the coastal zone of the sea. / Ed. R. D. Kosyan, I. S. Podymova, N. V. Pykhova. - M .: Scientific World, 2003. - 320 p.

Claims (2)

1. A method of calibrating turbidity sensors, which consists in registering a sensor signal depending on the turbidity of the liquid passing through it, characterized in that the sensor is placed in a closed loop of constant cross-section, in which directed motion of the fluid is created at a constant speed, ensuring a uniform suspension of particles, the required concentration of particles and their fractional composition is provided by adding to the liquid a weighted portion of particles of a given fraction. 2. A device for calibrating turbidity sensors, containing a vessel with a liquid, in which there is a mechanical drive with a regulator, providing its movement and a turbidity sensor with a measuring system, characterized in that the vessel is made in the form of a closed loop of constant cross section, into which the pump is connected, in the loading unit is fixed to the upper part of the circuit, and the calibrated sensor is placed in the descending branch of the circuit.