Magnetic flap level meter use in the process of field calibration method

Project Overview

　　In the actual manufacturing process of the instrument, manufacturers can also increase some additional technical means to make the level meter to expand more functions, so that it can be used in the actual production control. 2m above the large range of the magnetic flip-plate level meter measurement accuracy is usually comparable with the differential pressure transmitter, and therefore more and more by the user's attention. However, due to the environment of the measurement site and the use of conditions and the manufacturer's calibration of the environment is not consistent, and some even a big difference, resulting in many manufacturers labeled maintenance-free advantages can not be fully embodied, and the demand for testing has also increased.

　　Here we share with you what are the calibration methods for using magnetic flap level meter in the field.

• 1、The practical significance of on-site calibration in accordance with the description of the national calibration regulations, the level meter below 2m need to be calibrated through the standard tank device, more than 2m need to be calibrated by the analog method. However, by a large range of magnetic flap level meter itself size limitations, magnetic flap level meter more than 2m level meter in the laboratory installation problems, and regulations on the simulation of the calibration method has not been specifically described. Magnetic flap level meter then such level meter can not realize the online calibration? Summarized, the need to solve the following problems:
• 　　(1)Level meter measurement of the media density range is often wide, generally 0.8-1.2g/cm3, the density of the level meter measurement error of the impact of how to correct for.
• 　　(2)The installation of the magnetic flap level gauge liquid storage tank can not be absolutely vertical, then how to choose the measurement standardizer, how to measure, will be very important.
• 　　(3)On-site storage tanks are like a black box, and determining the level reference point for calibration is a critical issue.

　　In this paper, the side-mounted magnetic flip-flop level meter with (4-20mA) electric telecommunication signal is used as an example to explore the simple and effective on-site calibration method, in order to be able to achieve the purpose of measuring the level error and its uncertainty of the whole system under the on-site installation conditions, which is of practical significance.

• 2、The structure principle of the instrument Magnetic Flap Level Gauge is developed according to the principle of buoyancy and magnetic coupling. When the liquid level in the measured vessel rises and falls, the magnetic float in the body tube of the gauge rises and falls with it, and the permanent magnet inside the float is transmitted to the magnetic flip column indicator through magnetic coupling, driving the red and white flip columns to turn over, so as to realize clear indication of the liquid level. Through the opening and closing of the built-in reed switch contacts, the transmission of current or voltage signals is realized. Magnetic Flip Flop Level Gauge will generally be adjusted by simulation method (this method is not described in the regulations) at the factory to ensure that the supply is matched with the actual medium.
• 3、Specific field calibration procedures for liquid level meters
• 　　(1)First of all, to determine the density of the measured medium medium density can be measured with a standard densitometer, magnetic flap level meter can also be based on the specific information provided by the user to find out the density of the medium needs to be recorded for the record, to ensure that the density of the medium to comply with the requirements of the instruction manual of the liquid level meter. Although the theoretical density of the medium has an impact on the level meter value, but the actual use of the level meter zero and fullness value can be adjusted directly through the potentiometer.
• 　　(2)Next to determine the reference zero point a) with vernier calipers to measure the inner diameter of the connecting pipeline D, magnetic flap level meter in the upper part of the tank to determine a standard liquid level under the ruler point, such as conditions, can be polished into a groove to avoid the depth gauge swing, and make a mark; b) in the state of the tank does not come with the pressure of the tank manually to tank filling, when the water level is slightly higher than the level meter inlet pipe to stop the injection of water, the magnetic flip plate level meter to open the lower connecting Flange mouth manual ball valve E and loosen the tank and the school level meter between the connecting flange F (not removed, so that the water flow is not overshooting), until there is no surge flow in the pipeline, close the E, remove the flange, to be smooth liquid in the tank to open the E, and then wait for the drip state, stable for 1min (if necessary, can be drained through the drainage valve to improve detection efficiency); c) magnetic flip-flop level meter with a depth gauge tape measure from the point of measurement to the water surface between the distance ha, the actual zero level of the water level, the actual zero level of the level meter to the surface of the water surface between the water surface of the tank and the water level. The distance between the measurement point and the water surface ha, the actual zero empty height h0 = ha - D / 2, this state that the level meter measurement zero point.
• 　　(3)Calibration of the liquid level points a) install the flange, close the E, continue to fill the tank with water to the main scale of the flip-flop indicating the level to be calibrated, to be stabilized after the water surface to measure the output current Ii and the water level of the empty height hi, the actual level is: H0 = h0-hi = ha-D/2-hi; b) continue to other points of the measurement of the magnetic flip-flop liquid level meter until the full scale.
• 　　(4)Level zero and fullness of the adjustment in the determination of the reference zero point at the same time, adjust the zero potentiometer, so that the output signal is displayed as 4mA; fullness adjustment in the upper limit of the standard liquid level, adjust the full scale potentiometer, so that the output signal is displayed as 20mA. magnetic flip-flop level meter under the stroke of the measurement of the output if there is a deviation, refer to this method of adjustment. Field calibration needs to repeat the above steps for three return measurements.
• 4、Summarize the magnetic flap level meter field calibration of instruments and related devices used in the field is simple and practical, operable, solve a large range of liquid level instrumentation laboratory can not detect the problem, has a high practical value.