Degas the Vapor Source Tube
Vapor source liquids must be degassed thoroughly to remove air (and other dissolved gases) to achieve desirable results. It is very important to degas vapor liquids on a weekly basis to maintain purity.
Degas vapor liquids:
- on a regular, weekly basis
- when adding fresh vapor liquid
- when changing vapor liquids
The vapor tube may be degassed by using the vacuum method or the freezing method. The vacuum method is generally sufficient.
Vacuum Method
- Ensure the cold trap dewar has been removed.
- Display the instrument schematic and enable manual control. Ensure all valves are closed. Valves 1 (vacuum), 7 (isolation), and 8 (vapor) will be used.
Do not open Valves 1 and 8 concurrently. Doing so may cause damage to the instrument. |
- Open valves 1 and 7. Wait until the vacuum gauge reading is 10 mmHg (approximately 5 min).
- Close valve 1 and open valve 8; wait approximately 2 min.
- Close valve 8 and open valve 1; wait approximately 2 min.
- Repeat Steps (3) and (4) six times so that the vapor source will be degassed thoroughly (or until the 1000 mmHg transducer reads between 40 and 45 mmHg for water at 35 ºC in the vapor enclosure).
The pressure in the manifold will vary if using a vapor other than water at 35 ºC. Refer to a Saturation Pressure vs. Temperature table to determine the appropriate pressure for the vapor being used. |
Freezing Method
The vacuum method is typically sufficient for degassing water. However, the freezing method may be used when maximum purity is required.
It is very important to degas vapor source liquids on a weekly basis to maintain purity. |
- Place a dewar of LN2 on the instrument cold trap and another dewar of LN2 about the vapor tube using the supplied dewar and stand.
- Open valve 8 and evacuate until a vacuum of 10 mmHg is achieved.
- After 30 minutes, remove the LN2 from the vapor tube and close valve 8.
- When the water in the vapor tube warms nearly to ambient temperature, open valve 8 and allow evacuation to proceed for 10 minutes.
- Close valve 8.
Copyright © 2014 - 2018. Micromeritics Instrument Corporation. All rights reserved.