Methods of checking the airtightness of the device: pumping and pumping method, liquid difference method, micro-thermal method. The principle of checking the airtightness of the device is: by changing the size of the internal pressure, the formation of internal and external pressure difference, resulting in a water column. Liquid difference method, for example, its specific steps Zen He family step: assembled equipment, clamp the spring clip, to the long neck funnel constantly injecting water, so that the long neck funnel in the water is higher than the device inside the water surface, the formation of the liquid level difference, if the liquid level difference is observed to be stable and no decline, it is a good indication of the airtightness.
pumping and pumping method
Principle: the use of syringe pumping and pumping to make the device inside the air pressure becomes larger and smaller. Pumping, the internal air pressure becomes small, the external air pressure is large, the external air pressure is large, the external gas into the beat Kai into the formation of bubbles. When pumping, the air pressure inside the device is large, the water is pressed into the long-necked funnel to form a section of the water column.
Steps:
Assemble the device, the two-hole stopper of the conical flask, one puts the long-necked funnel, the other hole is connected to the syringe. Fill the long-necked funnel with water until the bottom of the long-necked funnel is submerged below the surface of the water. Use the syringe to pump or draw air into the conical flask.
When pumping outward, the lower end of the long-necked funnel has bubbles he cons come out, and when pumping inward, the liquid level in the long-necked funnel rises into a section of the water column, indicating a good airtightness.
micro-thermal method
Principle: by micro-thermal so that the gas inside the device by thermal expansion, overflow part of the gas, after cooling, the gas inside the device after the cold shrinkage of the pressure decreases, the outside air pressure is large, the water will be pressed into the conduit, the formation of a water column.
Assemble the device, one end of the conduit into the water, constituting a closed system, cover the test tube with both hands, and observe bubbles coming out of the mouth of the conduit in the water, and let go of the hand, the conduit enters into a section of the water column, indicating that the airtightness is good.