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How to solve the current over-range problem of pressure transmitter

Jan 16, 2019


How to solve the current over-range problem of pressure transmitter


When using a pressure transmitter, there are often some problems, the temperature measurement is not accurate, the measurement temperature changes fluctuate greatly, the pressure transmitter current exceeds the range, and the inspection reveals that there are many convex small points on the diaphragm, and the measurement medium It is steam, and the diaphragm that is pressed at a low point is inelastically deformed by ice. The liquid level gauge on the spot has a large deviation from the central control display. This situation is estimated to be frosted. It may also be that the temperature is too high and the oil is heated up.

Measuring steam generally uses condensed water as the pressure transmitting medium. Therefore, steam heating is required to prevent the condensed water from freezing. In addition, care should be taken not to allow the steam to directly contact the bellows for a long time, and the pressure tube should be placed on the unused transmitter. The condensed water is removed to prevent the temperature of the condensed water from being lowered, causing the water to condense to generate negative pressure suction, causing the negative pressure to damage the capsule. The diaphragm is flat overall, with only a dozen or so tip-sized bumps, and is not as frozen. The transmitters that measure steam should pay attention to the following points:

pressure transmitter

1, measuring steam, need to be accompanied by heat! Especially in winter, it is necessary to add heat and heat.

2. For pressure transmitters, it is necessary to add isolation tanks (condensation tanks) to prevent the high temperature of steam from affecting the bellows and silicone oil.

Pressure transmitters have gained a high market share due to their good performance and relatively close price. Therefore, although the quality of the pressure transmitter is relatively stable, it will be good after a long time. Some minor problems, in order to avoid these problems,

Here is a summary of some of the knowledge about the price of pressure transmitters, such as the price of pressure transmitters in different places may be slightly different. The following materials hope to be helpful to customers.

1. The environment at the equipment site is relatively harsh. The strong electric signal will generate various electromagnetic interferences. The lightning induction will generate strong surge pulses. In this case, a difficult problem encountered in the single-chip application system is how to be in a harsh environment. Reliably transmit small signals over long distances

Considering that the transmitter's high-frequency noise passes through the transformer mainly by the mutual inductance coupling of the primary and secondary coils, but by the primary and secondary parasitic capacitance coupling, the isolation transformer is isolated by the shielding layer between the primary and secondary. Reduce its distributed capacitance to improve resistance to common mode interference.

pressure transmitter

2. However, the price of the pressure transmitter is greatly limited when the signal needs to be transmitted over a long distance or the grid is in a large environment. The use of the voltage output type sensor is greatly limited, and the anti-interference ability is poor, and the line loss destroys the accuracy. And so on, and the two-wire current output type transmitter has been widely used because of its high anti-interference ability.

3. The magnitude of this potential difference depends on the concentration of the three cerium oxides, which corresponds to the moderate amount of hydrogen ions in the acidic solution being tested. If the appropriateness of bismuth, antimony trioxide and aqueous solution is regarded as 1, the electrode potential can be calculated by the Nernst formula.

The concentration of the acid-base solution is proportional to the magnitude of its conductivity. Therefore, as long as the magnitude of the conductivity of the solution is measured, the level of the acid-base concentration can be known. When the measured solution flows into the dedicated conductivity cell, if the electrode polarization and distributed capacitance are ignored, it can be equivalent to a pure resistance. When a constant voltage alternating current flows, the output current is linear with the conductivity, and the conductivity is proportional to the acid and alkali concentrations in the solution. Therefore, as long as the solution current is measured, the concentration of acid, alkali, and salt can be calculated.

4. This type of fault requires replacement of the amplifier board. The requirements of the transmitter in the design of the circuit and the quality of the process assembly are very strict. In the actual use, the line faults appear after the inspection and confirmation, and the manufacturer replaces the faulty circuit board to ensure the stability of the long-term operation of the instrument. Reliable pressure transmitter price.

5. Influence of the installation position of the differential pressure transmitter on the zero output The differential pressure transmitter has a small measuring range, and the self-weight of the sensing element in the transmitter will affect the output of the differential pressure transmitter. Therefore, it is normal for the zero position change in the installation of the differential pressure transmitter. The pressure sensitive component of the transmitter should be axially perpendicular to the direction of gravity during installation. If the installation conditions are limited, the transmitter zero position should be adjusted to the standard value after installation.

6. When the pressure on both sides of the transmitter is inconsistent, the working principle of the pressure transmitter and the color-to-pressure transmitter is the same as that of the differential pressure transmitter. The difference is that the pressure in the low pressure chamber is atmospheric pressure or vacuum.

7. We know that no matter what type of differential pressure transmitter, the positive and negative pressure chambers have exhaust, drain valve or cock; this is convenient for us to calibrate the differential pressure transmitter on site, that is to say The differential pressure transmitter can be calibrated by removing the pressure guiding tube. For this purpose, the dlr is machined with the same thread as the exhaust, drain valve or cock.

pressure transmitter

8. Thermal resistance is a primary component that converts temperature changes into changes in resistance. It is usually necessary to pass the resistance signal through a lead to a computer control device or other instrument. Industrial thermal resistance is installed at the production site, and there is a certain distance from the control room, so the lead of the thermal resistance will have a greater impact on the price of the pressure transmitter.

9. A strain gage is a sensitive device that converts strain changes on the device under test into an electrical signal. It is one of the main components of a piezoresistive strain transmitter. The resistance strain gauge application is more than two kinds of metal resistance strain gauges and semiconductor strain gauges. The metal resistance strain gauge has two kinds of filament strain gauges and metal foil strain gauges. Usually, the strain gauge is tightly bonded to the mechanical strain matrix by a special adhesive. When the stress changes due to the force of the substrate, the strain gauges are also deformed together, so that the resistance of the strain gauge is changed, thereby The voltage applied to the resistor changes.

The above precautions are the experience gained in the actual operation, which must be helpful to the customer. As long as you carefully use the pressure transmitter according to the above several precautions, you can get accurate data collection, improve the efficiency and reduce the efficiency. Unnecessary cost investment.

For more applications and selection of pressure transmitter products, please visit our website https://www.china-transmitters.com/