Why electromagnetic flowmeters should not measure high temperature fluids

CMS Repeatability: Readings, depending on the application Accuracy (flow field fully developed and radially symmetrical) Volume Flow: 1% reading, depending on application Readings, calibrated flow rate:

Readings, depending on the application Measurable medium: Acoustic impedance ratio of pipe wall to gas< 3000 Host ambient temperature -10 60 Power supply: (100....

240) vac (18...36) VDC Display: 2 x 16 characters, Dot matrix, with backlight power consumption:

1s (1 channel), 70ms optional. Measured quantity: Working volume Working condition mass flow rate, flow velocity, standard condition volume Standard condition mass flow rate (temperature and pressure compensation required) Accumulation:

Volume, mass calculation function: ....

Because the lining of the electromagnetic flowmeter is determined, the lining of the electromagnetic flowmeter has ruprene rubber, which can withstand the temperature to 80 degrees, and the PTFE lining has a maximum temperature resistance of 150, and then the lining will melt. There is the highest lining is a high-temperature ceramic lining of the domestic flowmeter manufacturers, as far as I know, no manufacturer can do it, or it is very unreliable.

An electromagnetic flowmeter is a fluid flow sensor that works on the basis of Faraday's law of electromagnetic induction. An electromagnetic flowmeter determines the flow rate of a fluid by measuring the conductivity and magnetic field strength in a conductive liquid.

However, gases have a very low electrical conductivity, so electromagnetic flowmeters cannot measure gas flow.

In addition, it is difficult for the gas to be affected by the magnetic field, so the electromagnetic flowmeter cannot accurately measure the gas flow even with a strong magnetic field.

In contrast, gas flow sensors typically use methods such as pressure sensors or temperature sensors to measure gas flow. Imitation posture.

The measurement principle of the electromagnetic flowmeter is based on Faraday Soxiang's magnetic induction law, which is composed of two parts: a sensor and a converter, which is used to measure the volume flow of conductive liquids with a conductivity greater than 5 s cm. In addition to measuring the volume flow rate of general conductive liquids, it can also be used to measure the volume flow rate of strong acid, strong alkali, strong corrosive liquids and liquid-solid two-phase suspended liquids such as slurry and pulp. Now it has been widely used in flow metering in industrial sectors, municipal management, water conservancy construction and other fields.

The conductivity of the gas is very low, so the electromagnetic flowmeter cannot measure the gas flow.

What is the reason why the magnetoelectric flowmeter of our unit, when there is no material flowing through, has a large flow rate display from time to time?

What is the reason why the magnetoelectric flowmeter of our unit, when there is no material flowing through, has a large flow rate display from time to time? Hello dear, first; Straight pipe sections may not be sufficient; Second; It should be that the motor interferes with the (main) motor power is too large and the distance is too close. First:

See whether the impeller of the pump body is in good condition Second: whether the installation position meets the standard Third: whether the liquid is full of pipes Fourth:

The fifth situation of on-site interference: whether the flowmeter itself is working normally 1, magnetic field interference 2, straight pipe section 3, there is a problem with the flowmeter itself, first see whether the motor fluctuates, the high voltage may have an impact on the excitation, and the reason for the flowmeter itself is very good to judge: listen to the change of some parameters, you can try to adjust the damping coefficient is also effective, you can try.

Thermal flow meters are used in a wide range of applications to calculate the fluid's fluid-sensitive start-up state based on its temperature and volume. It is an application and embodiment of the principle of heat conduction, the thermal bypass mass flowmeter is one of its types, the thermal flowmeter is basically based on measuring gas, so many people think that this instrument can only be used to measure gas, and the function is relatively simple, so is this understanding correct?

This decision is a bit one-sided, gas is only the main medium it is used to measure, because whether it is the working principle of the thermal flow meter, or the product structure is more suitable for measuring gas, so it will cause the illusion that only gas can be measured. In addition to gases, some liquid levels, semi-solid media, thermal flow meters can also be measured.

The measurement principle used by the thermal flowmeter to measure the flow rate of liquids is basically similar to that of gas, and can be used to measure the flow rate of liquids and semi-solids such as clean water, sewage, oil, etc.

Through today's bridge, I believe you know that thermal flow meters can not only be used to measure gases, but also flow measurement of liquids and other types of media. However, it should be noted that since measuring the medium outside the gas is not what the thermal flowmeter is good at, it is necessary to learn from the manufacturer whether the type of product used is suitable for measuring liquid and other media before the measurement begins, and ask for instructions on how to use it, and operate in strict accordance with the requirements of use.

1. The country uses the absolute value of the maximum relative percentage error of the instrument as the accuracy grade, where:

The accuracy of the first-class standard meter is:

The accuracy of the secondary standard meter is:

The accuracy of the general industrial instrument is:1

Relative percentage error = (measured value of north measurement parameters - standard value of north side parameters) (upper limit value of ruler - lower limit value of ruler) * 100%.

2. How is the accuracy level of China's instrument divided?

Fundamental error: Fundamental error, also known as reference error or relative error, is a simplified relative error. The basic error of the meter is defined as:

Basic error = (maximum absolute error instrument range) * 100 = = (indication value of the detection instrument - true value to be measured) max (upper limit of measurement - lower limit of measurement) * 100%.

Accuracy (referred to as precision).

In order to facilitate the transmission of measurement values, the state uniformly stipulates the accuracy (accuracy slow) grade series of instruments. The basic error of the instrument is removed from the "" and "%" numbers, and it can be set into the national unified instrument accuracy level series.

At present, the commonly used accuracy grades of instruments produced in China are, etc. If the basic error of a temperature measuring instrument is , the accuracy level of the instrument is considered to be in accordance with the level. If the basic error of a temperature measuring instrument is , the accuracy level of the instrument is considered to be in accordance with the level.

The smaller the progression, the higher the precision (accuracy).

The accuracy level of the instrument used in scientific experiments is above or above; Most of the instruments used for industrial testing are at the level, among which the standard tables used for calibration are mostly or level, and the field is mostly at the level.

Most of the instruments used for industrial testing are at the level.

I've seen 3 different expressions in different places:

1.China's industrial instrument grade is divided into ,,, seven grades, and marked on the instrument scale or nameplate.

2.China's electrical instruments are divided into ,,, seven grades.

3.According to the national unified division of the instrument accuracy level is0 etc.

Generally speaking, people who know a little about physics know that there is a law with a wide range of applications in nature Faraday's law of electromagnetic induction: when a conductor moves in a magnetic field, at both ends of the conductor perpendicular to the direction of the magnetic field and the direction of motion, an induced electromotive force will be generated, and the magnitude of the electromotive force is proportional to the speed of the conductor and the magnetic induction intensity of the magnetic field.

The electromagnetic flowmeter uses this principle to measure the volumetric flow rate of the conductive fluid in a closed pipe.

The answer to the question you asked was that the fluid must be greater than or equal to 5 us cm in order to meet the conditions of a conductor in Faraday's law of electromagnetic induction and to make accurate measurements.

Electromagnetic flowmeters can only measure conductive liquids, not gases, due to their measurement principle.

The maximum temperature that different flow meters can withstand is different for operation. Strictly speaking, the maximum temperature that a general flow meter can withstand is 100 degrees Celsius. The allowable temperature of each instrument varies depending on the conditions.

Generally, the instrument will have a manual when it is **, and the corresponding use parameters are marked on it, for example, the standard orifice plate in the market is used as shown in the following figure:

There are many types of flow meters, and the allowable temperatures of various detection components are also different. Any detection beyond the permissible operating temperature is not allowed, and this is clearly stated on the instruction manual of the flow meter. For example, the inner lining of the electromagnetic flowmeter is made of nylon, which has low temperature resistance, so it is not suitable for detecting steam flow.

The orifice flowmeter is used, and the detection membrane box of the differential pressure transmitter can not directly contact the high temperature of steam, and the method of pouring balanced water into the impulse pipe is used to isolate the high temperature of the steam, so that the orifice flowmeter can detect the flow rate of steam.