防爆的3个基本控制方法 3 Basic Control Methods for Pressure Gauge Explosion Protection
1. The principle of the task in the field of explosion control is: the design and manufacturing standards of flameproof and explosion-proof methods are extremely strict and the operating procedures of the device, wiring and maintenance are also very strict;
Strictly design, manufacture and install all interfaces in accordance with the specifications, so that the explosion in the shell will not cause the explosion of dangerous gases (explosive gases) outside the shell; this method determines the explosion-proof electrical
Equipment, pressure gauges are often very large and heavy, and the operation must be powered off, but it is also the most useful method in many situations;
柜； 2. The principle of the task of controlling explosive gases is: a positive pressure explosion - proof pressure gauge cabinet commonly used for re-analyzing the explosion protection of pressure gauges and placing computers, PLCs, operating stations or other pressure gauges on the scene;
In a sealed box, filled with clean or inert gas that does not contain explosive gas, and insist that the pressure inside the box is slightly higher than the pressure outside the box, and install the pressure gauge in the box;
3.Control detonation source
According to international standards and China's national standards, when a physical safety device in the safety zone of the safety fence is in normal tasks, one fault occurs, and two faults do not cause explosive gases to mix.
When an object explodes and the safety grid technique is applied, the electrical energy provided by the on-site pressure gauge is restrained in a safe area where neither a sufficient explosion of sparks nor a temperature rise of the external surface of the pressure gauge can occur.
Correct selection of pressure gauge
The correct selection of pressure detection instruments mainly includes determining the pressure type of the instrument (such as measuring gauge pressure or differential pressure or negative pressure or absolute pressure), measuring range, measuring pressure unit, resolution,
Accuracy and sensitivity, external dimensions and whether remote transmission is required and other functions such as indication, recording, adjustment, alarm, etc.
The main basis for selection:
1. It is suitable for the observation of workers. According to the location and lighting conditions of the measuring instruments, instruments with different diameters (dimensions) are selected, such as some special workplaces such as boilers and some reaction kettles.
Generally, a 200mm diameter or larger will be selected;
2. The measurement requirements of the process of production, including the range and accuracy, in the case of static testing (or slow change), the maximum value of the measured pressure is selected to use the pressure gauge full scale
Two-thirds of the value. In the case of pulsating (fluctuation) pressure, the maximum value of the measured pressure is one-half of the full scale value of the pressure gauge;
The accuracy levels of commonly used pressure detection instruments are 0.25, 0.4, 1.0, 1.5, and 2.5, which should be selected from the accuracy requirements of the production process and the most economical point of view.
The maximum allowable error of the meter is the product of the meter's range and the accuracy level percentage. If the error value exceeds the accuracy required by the process, the pressure meter with a higher level of accuracy needs to be replaced.
3. Suitable for installation by staff. According to the installation position and interface specifications of the testing instrument, select instruments with different installation methods and interfaces. Generally used in the radial installation type on the pipeline, easy to install
And reading, generally use the axial front side or axial bracket installation type on the control panel of the equipment, as for the ridge pattern, it needs to be made according to the reserved interface, generally you can ask the manufacturer
It is required to make it. If it can not be customized, it can be achieved by reducing or adapting the connector. Generally, it does not affect the use of the instrument and the accuracy of the measurement.
4. On-site environmental conditions, such as ambient temperature, vibration, corrosion, and humidity. For shockproof pressure gauges used in vibrating environmental conditions, all stainless steel pressure gauges that are resistant to corrosion can be used.
5. The properties of the measured medium, such as state (gas, liquid), viscosity, corrosiveness, degree of pollution, temperature, flammability and explosiveness, etc. Such as acetylene meter, oxygen meter, with "oil-free" sign,
等。 Corrosion-resistant pressure gauges, high-temperature pressure gauges, diaphragm pressure gauges, etc., which are specially used for special media.