Normal use of stainless steel earthquake-resistant meter

According to the allowable error of process production and the selected instrument mileage, the allowable reference error of the instrument is calculated, and the precision of the instrument is determined in the precision grade specified by the state. Generally speaking, the more precise the instrument is, the more accurate and reliable the measurement result will be. However, it cannot be considered that the higher the accuracy of the selected instrument, the better, because the more precise instrument is generally more expensive, and the more troublesome it is to operate and maintain. Therefore, on the premise of meeting the technological requirements, instruments with low precision, low price and durability should be selected as far as possible.

1. The operating environment temperature of the instrument is -40~70℃, and the relative humidity is not more than 80%. If it deviates from the normal operating temperature by 20 5℃, the additional temperature error shall be included.

2. The instrument must be installed vertically, and strive to keep the same level with the measuring point. If the difference is too high, it is included in the additional error caused by the liquid column, so it is unnecessary to consider when measuring gas. When installing, block the explosion-proof port at the back of the case to avoid affecting the explosion-proof performance.

3. The measuring range of the instrument in normal use: it shall not exceed 3/4 of the upper limit of measurement under static pressure and 2/3 of the upper limit of measurement under fluctuation. Under the above two pressure conditions, the low pressure of the large pressure gauge should not be lower than 1/3 of the lower limit, and the vacuum part should be used completely when measuring vacuum.

4. When in use, if the instrument pointer fails or the internal parts are loose and can't work normally, it should be overhauled, or contact the manufacturer for maintenance.

5. The instrument should avoid vibration and collision to avoid damage.

6. When ordering, please indicate: instrument model and name; Measuring range of the instrument; The accuracy grade of the instrument deviates from the requirements of positive packaging and others.

7. The stainless steel shock-resistant pressure gauge is not suitable for strong oxidant environment such as oxygen, chlorine, nitric acid and hydrogen peroxide.

Three explosion-proof principles of common instruments in pressure gauge manufacturers

Release date: April 30, 2021 Author: Wuxi Quanjun Instrument Co., Ltd. Click: 130

To prevent explosion is to avoid the coexistence of three conditions for explosion. Because oxygen (air) is everywhere, it is difficult to control. Therefore, controlling explosive gas and detonating source are two common explosion-proof principles. There is another explosion-proof principle in pressure gauge manufacturers: controlling the explosion range.

Three common explosion-proof principles in instruments:

1, control explosive gas artificially in a dangerous place (we call the industrial site with three conditions required for explosion at the same time as a dangerous place) to create a space without explosive gas, and install the instrument in it. The typical representative is the positive pressure explosion-proof method Exp.

The working principle is: a sealed box is filled with clean gas or inert gas without explosive gas, and the pressure inside the box is kept slightly higher than that outside the box, and the instrument is installed in the box. It is often used for explosion-proof of on-line analytical instruments and positive pressure explosion-proof instrument cabinets that put computers, PLC, operating stations or other instruments on site.

2, control the explosion range artificially limit the explosion in a limited local range, so that the explosion within this range will not cause a larger explosion. The typical representative is the flameproof explosion-proof method Exd.

The working principle is: design a solid shell for the instrument, and strictly design, manufacture and install all interfaces according to standards, so that the explosion in the shell will not cause the explosion of dangerous gas (explosive gas) outside the shell. The design and manufacturing specifications of flameproof and explosion-proof methods are extremely strict, and the operating procedures for installation, wiring and maintenance are also very strict. This method determines that the flameproof electrical equipment and instruments are often very heavy, and the operation must be cut off, but it is also an effective method in many cases.

3. Control the detonating source to artificially eliminate the detonating source, which not only eliminates the spark enough to detonate, but also eliminates the surface temperature rise enough to detonate. The typical representative is the intrinsically safe explosion-proof method Exi.

The working principle is: using the safety barrier technology, the electric energy provided to the field instrument is limited to a safe range that can neither generate enough sparks nor generate enough temperature rise on the instrument surface. According to international standards and national standards of our country, when there is any fault (not exceeding 250V voltage) of the equipment connected to the safety barrier, the intrinsically safe explosion-proof method ensures the explosion-proof safety of the dangerous site. Exia-class intrinsically safe equipment will not cause explosion of explosive gas mixture when it works normally, one fault occurs and two faults occur. Therefore, this method is a safe and reliable explosion-proof method.

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