Glove Box Operation and Maintenance

Vacuum Atmospheres Model HE-493

General Mechanism of the Glove Box

Nitrogen Supply

 1.  Nitrogen is provided directly to the glove box. The antechamber is filled with nitrogen through the glove box.

 2.  The glove box and the antechamber are connected by two valves: refilling (external right wall of the glove box) and evacuation (before the antechamber).

Pressure Control

 1.  The refilling of the glove box is controlled by the automatic pressure control.

 2.  The upper line indicates the level of over-pressure or under-pressure in the glove box with orange dots. Dots to the right indicate under-pressure. Dots to the left indicate over-pressure.

 3.  The lower line allows fixing the level of over-pressure/under-pressure with two red dots, each indicating respectively the maximum or the minimum. They can be moved by turning the 2 small buttons.

Vacuum System

 1.  Vacuum is provided by a pump which is always turned on.

 2.  Inside the glove box, on the right wall is a black valve. When the valve is pointed in the direction of the west (it points to the glove box window), it means that the glove box is directly connected with the refilling valve. If the black valve points in direction of the east (it points behind the glove box), the freeze-dry tubing system is connected with the refilling valve.

Working Inside

Introducing Material Into the Glove Box

 1.  The inside (left) door of the antechamber must be closed securely, then the right door is opened, the material placed on the sliding tray, and the right door closed again. To close the door, make sure that the 2 black marks fit together.

 2.  Purge the atmosphere of the glove box has to be purged and refilled with Nitrogen.

 3.  Repeated cycles of evacuation and refilling have to be done as follow:

 4.  Cycle One: evacuation: make sure that the refilling valve is closed and the black valve inside the glove box points in direction of the west (to the window).

Open the evacuation valve and check on the manometer that the vacuum reaches -100 in Hg.

Close the evacuation valve.

Move the two red dots to the left (indicating a maximum gas filling). The automatic pressure control will fill the glove box. When the orange dots indicate an over pressure in the glove box (orange dots are then on the left) the refilling valve can be opened. The orange dots must never go to the right. When you reach this limit, close the refilling valve.

 5.  Cycle two: Open the evacuation valve and reach a vacuum of –100 in Hg.

Close the evacuation valve and open the refilling valve. The orange dots must never go to the right. When you reach this limit, close the refilling valve.

 6.  Repeat Cycles one and two 4 times. (If many objects have to be put into the glove box, 5 cycles are recommended. Indeed, with a lot of material, the amount of oxygen trapped inside this material is larger and risks bringing too much oxygen inside.)

 7.  Last cycle: Refill the antechamber to reach a pressure of 0 (it will require several aperture and closure of the refilling valve because the gas is too slowly provided by the automatic pressure control system).

 8.  For the usual working conditions inside the glove box, set the pressure on the automatic pressure control system to +2 in water and –1 in water (red dots).

 9.  After the purging cycles have been completed, the door between the glove box and the antechamber can be opened.

Additional hints:

As a vacuum is created in the antechamber, do not forget to close all bottles with liquids, to avoid a spill. Also, if necessary to write something down inside the glove box, do not use a pen because the ink could leak. Therefore, it is recommended to use pencils.

Before starting the evacuation cycles, make sure you have all the necessary material. In case something has been forgotten, a lot of time will be lost to repeat all the procedure.

Working With Hands in Gloves

 1.  Make sure the automatic pressure control system is set to +2 in water and –1 in water (red dots).

 2.  If you work with liquids inside the glove box, it is recommended to fill the dewar with liquid nitrogen (on the bottom, on the right side of the glove box). This practice assures that liquid vapors are trapped before the air reaches the vacuum pump.

 3.  When you have finished your work inside the glove box, please do not forget to clean it up. The gloves too should be cleaned with a towel.

Removing Material from the Glove Box

 1.  Put all the material in the antechamber and close the antechamber left door (isolating the antechamber from the glove box).

 2.  Before opening the right door of the antechamber, check again that the left door is well closed.

Checking the Oxygen Content Inside the Glove Box

Regeneration of the Purifier

Verify that the Purifier is working properly

Equipment needed: hand magnet and voltage meter

Procedure:

1. Remove the cover to the junction box at the top of the purifier (be careful, the potential in the box could be about 110 volts).
2. Move the toggle switch on the control panel to the “Off” position.
3. When the squirrel cage fan stops, close the circulation valves (upper and lower).
4. Check the voltage in the junction box between the white and black wires. It should give a low (maybe even 0) voltage reading.
5. Move the toggle switch on the control panel to the "Start" position, then check the voltage in the junction box between the white and black wires. It should read 110 volts. Replace the cover on the junction box.
6. Locate three solenoid valves above and below the control panel. One will be labeled “Vent”; one, “Regeneration Gas”; and one, “Vacuum.”
7. Place a hand magnet near each of these valves. No attraction should occur.
8. Be sure that the purge gas is connected, the main valve on the tank opened, and all valves in the purge gas line opened.
9. Move the timer switch to the “Heat, Regeneration” position, wait 2 minutes, place the hand magnet again near each of the solenoid valves. It should be attracted to the “Vent” and “Regeneration Gas” valves, but not to the “Vacuum” valve.
10. Observe the flow meter and be sure the ball inside the tube is indicating gas flow. For 5% H2 in Ar, the flow rate should be 25 cfh (cubic feet per hour); for 5% H2 in N2, 20 cfh.
11. Turn the timer switch on the control panel to the “Vacuum” position, wait 3 minutes. Place the hand magnet again near each of the solenoid valves. It should be attracted only to the “Vacuum” valve.
12. If all measurements to this point were correct, the mechanics of the system are working fine.

Regenerating the Purifier

1. Be sure that the purge gas is connected, the main valve on the tank opened, and all valves in the purge gas line opened.
2. Move the toggle switch on the control panel to the “Off” position.
3. When the squirrel cage fan stops, close the circulation valves (upper and lower).
4. Move the timer switch on the control panel to the “Start” position, then turn the toggle switch on the control panel to the “Regenerate” position.
5. Observe the progress of the timer switch; when it reach the “Heat, Regeneration” position, check the flow meter and be sure the ball inside the tube is indicating gas flow. For 5% H2 in Ar, the flow rate should be 25 cfh (cubic feet per hour); for 5% H2 in N2, 20 cfh.
6. Continue to observe the progress of the timer switch; after it reaches the “Vacuum” position, wait for several minutes to an hour.
7. Turn the toggle switch on the control panel to the “Recirculate” position, and slowly open the lower, then the upper, circulation valves. Some rushing of gas from the glove box into the purifier should be heard.
8. Allow the atmosphere to recirculate for some hours before use or before checking the O2 level with the O2 meter.