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Atmosphere furnace detection air tightness furnace chamber clean

1. Check the air-tightness of the atmosphere furnace. After installing the flange, keep the pressure for 2 hours to see if the pressure gauge is deflected and proceed to the next step when the air-tightness is intact.
2. Use a vacuum pump to pre-evacuate the gas in the atmosphere furnace:
    (1), connect the air outlet with the vacuum hose.
    (2), pre-evacuate the furnace cavity to -0.08MPa,
   (3), then pass in protective gas (nitrogen or argon is better),
    (4), pre-evacuate the furnace cavity again, and then pump down to -0.08MPa
   (5). Repeat this several times to meet the atmosphere requirement in the furnace.
 3. After the atmosphere furnace is cleaned, vacuum the furnace body, and then flush hydrogen into it. Since hydrogen is a dangerous gas, it will explode with air when the content is between 4%-75%. Therefore, the furnace must be inspected after cleaning the furnace. Whether it is washed well, that is, whether the hydrogen inside the furnace is pure.
 The specific method is: take a small test tube and collect a test tube of H2 or ammonia decomposition gas with the downward air method, block the mouth of the tube with your thumb, approach the flame, loosen your thumb, and listen to the crackling sound: sharp crackling sound-impure , A slight crackling sound---pure.
 4. After detecting the purity of hydrogen, let hydrogen enter from the back and exit from the front. In order to prevent excessive accumulation of hydrogen in the furnace and the pressure in the furnace is too high to cause danger, try to insert the gas outlet into a mineral spring filled with water In the water bottle, the mineral water bottle should be placed outdoors, the gas outlet valve should be set larger, and the gas flow can be adjusted through the inlet valve.
5. After the gas flow is normal, heat the furnace,
6. When shutting down, turn off the furnace first and then turn off the gas, and then turn off the gas after the furnace has cooled down. So as not to cause danger.