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Working principle of gas pressure regulator

Add Time:2015-11-20

In order to clarify the working principle of the regulator, it is necessary to clarify the problem: what are the conditions of gas safety combustion? Solid fuel combustion to safety, must have two conditions: one is the amount of combustion gas
(air or oxygen), two is the burning material to maintain a certain temperature (usually above.). When the solid is burning, the heat transfer mode of the part of the combustion is conducted and radiated, and the burning direction is from the outside to the center. Solid combustion occurs when the thermal expansion, the volume becomes large, but the change is small, the displacement is almost zero. When the gas is burning, the heat transfer mode of the part of the non fired part has been increased, but the convection mode is increased, and the direction of combustion is outside the center. When the gas burning, the thermal expansion occurs, the volume of the generated object is hundreds of times, and the displacement of the top of the gas is at a rapid speed. Therefore, only to meet the above two conditions, is unable to make gas safe combustion. Modern combustion theory tells us that combustion of gas safety must also meet the three conditions, namely, to maintain a certain size, pressure difference and making gas outlet velocity is equal to the burning velocity. Only in this way, in a certain range to achieve dynamic balance, the flame will be able to maintain a steady state, so as to achieve the safety of gas combustion. If the pressure is too large, will make air speed is greater than the burning velocity, causing flame out fire hole distance combustion, the terms of this phenomenon is called away from the flame. If gas pressure continues to rise, the flame will be away from the fire hole more distant combustion, the flame stability was further damaged, the flame is erratic, until finally completely extinguished. This phenomenon is called off the fire. When taking off the fire, gas to leak, forming a large amount of toxic gases or explosive gases in the air, extremely easy to cause the accident. If the gas pressure is too small, the combustion speed is greater than the rate of the gas, causing the flame will continue to burn in the fire hole. This phenomenon is called tempering. When tempering, the formation of a hypoxic state of incomplete combustion, resulting in a large number of toxic gases, but also out of oil gas, it is also very easy to cause accidents. A large number of experiments have been made by the engineering technology personnel, not only to maintain the gas safety combustion to maintain a certain pressure difference, but also confirmed the different components of the gas, the air pressure difference is not the same. For example: artificial gas, 80 - 100mm water column; liquefied petroleum gas, 250 - 350mm water column. 2940Pa is the average of these two values. Let's go back to the regulator's principle. While (i.e. ventilation switches) have the US Open on the cylinder angle valve, high pressure oil and gas through the air inlet pipe opening valve pad into the gas chamber, with the increase in the gas chamber gas, the gas chamber pressure increases, force the rubber membrane to bulge. The air chamber volume gradually becomes smaller. When the pressure in the upper chamber is greater than the atmospheric pressure, the indoor air is slowly discharged from the breathing hole. In this process, right end of the lever to move up and left under pressure, inlet nozzle gradually close, to stop gas supply, so that the gas chamber pressure is no longer increasing. When opening the switch for a gas cooker, because gas is output outwards, under the gas chamber pressure become small, rubber membrane concave and drive lever right left end downward move, open the valve pad, high-pressure oil and gas into gas chamber. In this process, the gas chamber volume gradually becomes larger. When the pressure is less than the outside atmosphere, the air enters into the upper chamber from the outside through the breathing hole. Therefore, in the stove combustion process, rubber membrane does not stop on the concave convex, valve pad is driven by a lever, with the continuous opening and closing. In the dynamic change, we as long as the guarantee that the surge in leverage, it left and right arm (note left short right long) long, there is a reasonable proportion, and spring and the rubber membrane on the right end of the lever and applied a size appropriate force, so that we can make valve pad opening time is far less than the closing time, and let the time a proper ratio. The appropriate ratio, it can ensure that the air chamber pressure, always larger than the upper gas chamber 2940Pa. For the gas chamber pressure, it can be considered that the atmospheric pressure value of the outside world. This makes the gas away from the fire hole at the pressure, always greater than the atmospheric pressure value of about 2940Pa, gas in the steady state combustion. This is the first place in the design of the regulator. Second subtleties, reflected in the design of the breathing hole, that have great originality. One is why the breathing hole on the edge of the valve cover? Instead of the other position where the drill is easy to drill. Two is the diameter of the breathing hole is 0.8 m, can only through the most small of the rust needle, why is such a small aperture? A small hole is drilled on the edge of the valve cover to keep it close to the rubber membrane. If the air pressure in the air chamber is too large, the rubber membrane is raised upwards, and immediately the breathing hole is blocked, and the air in the upper air chamber is discharged from the air. According to Boyle's law, it can be known that the air is confined to a certain quality in the upper air. Is the pV= constant. To prevent the rubber film from the upper and lower atmospheric pressure is too large and damaged, to avoid the damage caused by the diaphragm of oil and gas leakage accident. Breathing hole diameter of 0.8 mm m, but Kong Shen is about 1cm, here the full application of fluid mechanics knowledge. When the fluid is in motion, the friction force will be in the presence of the retardation. The smaller the hole area, the greater the depth, the greater the internal friction, the damping effect is obvious - the flow of smaller per second. In this way, the upper air chamber is on the exhale and suction