汕头丝袜减压-汕头丝袜减压_主页

在巢湖酒店晚上怎么叫服务

Current location: home page > Industry trends >/ liquid nitrogen degassing operation method

Operation method of liquid nitrogen removal

Time: 2020-09-29 11:13 Source: unknown Author: Bander liquid nitrogen tank Click: second
Do solution polymerization experiment, how to operate? liquid nitrogen tank

First, use the vacuum pump to pump out the vacuum, and then conduct the liquid nitrogen operation after repeated several times.

Steps:

1 pressure nitrogen

2 freezing

Vacuum during freezing

Atmospheric pressure to 4 nitrogen

5. Unfreezing and recompression of nitrogen

6 and then 2, so repeat the cycle.

The reaction glass instrument used (commonly known as sealing pipe) should have a set of vacuum line device (oil pump, vacuum line) for vacuumizing. The reaction bottle (containing reaction liquid, commonly known as sealing pipe) is frozen with liquid nitrogen, and then vacuumized by vacuum line, and then thawed with hot water (vacuum can be continued during thawing, but the bubble of reaction liquid should not be too large to prevent the solution from being pumped up) When the bubble is not enough, freeze it with liquid nitrogen, continue to open the valve, and then thaw with hot water, three freezes and three thaws! It's impossible to just talk about it. Practice it!

It's OK to use an ordinary flask. Freezing is not to freeze the nitrogen, but to freeze your reaction liquid. In this way, when vacuumizing, the boiling point will be lowered, and the liquid with low boiling point will be directly pumped into the pump under high vacuum. After freezing, the purpose of pumping is to pump away the oxygen. The oxygen will not be frozen by your liquid nitrogen, and then the liquid will be filled with nitrogen Nitrogen is removed so that the oxygen in the reaction bottle can be removed without pumping the reagent away. First freeze with liquid nitrogen (in order to avoid pumping your reagent away), when the reaction liquid is solid, then vacuum the reaction bottle to remove oxygen. After pumping for a while, pass nitrogen or argon into the reaction bottle. At this time, the liquid nitrogen can be removed. In such a hot day, it is not necessary to thaw with hot water. This operation repeated three times is generally enough.

Others do this:

Generally, the container used is multi port (we use 4 ports), one of which is inserted with a thermometer, one is used to pass nitrogen, and the other is used for adding reagent during the process (and the exhaust port needs to be sealed with rubber plug (with 2 ports of suitable size). The three ports are all around the container, and the last one is used for stirring in the middle Mix.

Ventilation of nitrogen: the nitrogen is passed through the decompression valve and connected with an opening of the reaction vessel. liquid nitrogen tank

If the experimental requirements are high, the nitrogen should first pass through the bottom of the container to discharge the air for about 10 minutes, and then the pipe extending into the container should be put back above the liquid level. Wait for 10 to 20 minutes after all the reagents have been added. Plug all the ports with rubber plugs and turn off the nitrogen. (this question is reproduced in the wood bug Forum)

Related contents

shrink
  • Telephone consultation

  • 010-80204245
  • Wechat consulting