The VAC Glovebox is a controlled atmosphere apparatus. It provides an inert environment for handling highly reactive materials.
The Glovebox has four accessories used to create and monitor its atmosphere:
- Pedatrol (PC-1): Provides manual and automatic control of the pressure in the glovebox.
- Dri-Train (HE-493): Removes excess oxygen and moisture from the atmosphere in the glovebox.
- Oxygen Analyzer (AO-316-C): Monitors trace oxygen in the inert atmosphere in the glovebox.
- Moisture Analyzer (AM-2): Monitors moisture content in the inert atmosphere in the glovebox.
Creating an Inert Atmosphere Set the left red pointer of the photohelic to 5-inch positive, and the right red pointer to 4-inch positive. Turn the photohelic on. Open the refill valve to the loading chamber half way. Also open the loading chamber hatch. This causes the pedatrol to continually push the inert gas in and push out the existing gas. The pressure on the inert gas can be raised from 20 psi to 40-50 psi to speed the process. Never let the pressure in the glovebox drop below 2-inches positive Approximately 8 glove box volumes of gas should be used for a good purge. Close the loading chamber hatch and the loading chamber refill valve. Set pedatrol to normal operation pressure and return inert gas regulator to 20 psi. After purging Oxygen content should be ~200 ppm. Sample Handling Passing specimens and instruments into the glovebox. Make sure that the refill valve and the chamber hatch on the inside of the glovebox are closed. Open the chamber hatch on the outside of the glovebox. Load specimens and instruments. Make sure that all bottles are open and any part of anything going in is not capable of holding air. If not the glovebox could be contaminated. Close outer hatch. Open evacuate valve and wait for it to vacuum to as far as it can (usually takes a few minutes). Open refill valve partially- watch the pressure on the pedatrol and make sure the pressure doesn't drop too low- and refill chamber until pressure in chamber is 10 in Hg. Open evacuate valve again and repeat previous steps 2 or 3 times to ensure that there is no residual air. After repeating open refill valve slowly until chamber is same pressure as glovebox. Open chamber from glovebox end. Pedatrol Operation Manual Operation Turn the Photohelic 'off.' Using the foot pedal: - Raise pressure by pressing on right side of pedal. - Lower pressure by pressing on left side of pedal. Pressure is still shown on the Photohelic even though it is off. Automatic Operation Turn the Photohelic 'on.' Set the desired pressure of the glovebox using the Photohelic: - Set the maximum high pressure with the left red pointer. - Set the minimum low pressure with the right red pointer. The pressure will remain as desired as long as the Photohelic is on and there is enough inert gas pressure. Dri-Train Operation Regenerating Follow the instructions on the side of the regeneration controller: Close A & B valves (Dri-Train inlet and outlet valves), turn timer to start. Turn switch to regenerate. Make sure the the forming gas is turned on. After the heat cycle ends(3 hours) be there when the regeneration cycle switches to purge. The alarm for the gas will most likely go off a few times. Reset it and set the flow to 5 psi. After 5 hours, minimum, turn switch off, open valve B (the Dri-Train Outlet Valve). After 10 hours, minimum, open valve A (the Dri-Train Inlet Valve). Change the oil in the vacuum pump. Using Make sure the dri-train and blower are plugged in. Open the valves. Regenerate once a month if used often. Oxygen Analyzer Operation Calibrating Note: perform this operation quickly, the longer the fuel cell is exposed to 209,000 ppm Oxygen, the longer it takes to recover. Place range switch on CAL. Hold CALIBRATE/NORMAL switch to CALIBRATE. The analyzer is now taking a sample of air from the fish pump on top of the analyzer. Adjust the flow meter so that the flow rate is 1 scfh. Unlock the "span" control knob. Adjust until the meter pointer is over the "CAL" mark on the scale. This is the air calibration. Relock the "span" knob. Release the CALIBRATE/NORMAL switch. <1 ppm Reference Mode This mode gives a reference to a known substance with <1 ppm Oxygen content. Switching to this should yield <1 ppm, although I've never seen it below 3 ppm. Turn the forming gas on. Set flow to 1 scfh. Make sure that the forming gas is on. Sampling Mode Switching to this takes a sample of atmosphere from the glovebox. If the glovebox is calibrated correctly an accurate reading of Oxygen content will be displayed. Maintanance Replace the fuel cell once a year. Last replaced: July 2005 Moisture Analyzer Operation Calibrate: Turn knob from 'off' position to the calibrate 'cal' position. After 15 minutes the meter should read 1327 +/- 3 If not refer to manual, if so continue using Read: Turn knob to the 'read' position The value on the display is not the moisture content in ppm, but is a reference. Use this chart to decipher the amount of moisture in the glovebox.