A glove box has several uses:
1) Provide an inert atmosphere for chemical reactions sensitive to normal atmosphere (e.g. to oxygen or humidity) (these are often called ‘dry boxes’ or ‘controlled atmosphere glove boxes),
2) Provide an inert atmosphere for welding metal (the mBraun TIG-1010 is specifically designed for this),
3) Contain toxic chemicals or biological agents, which could harm the experimentalist,
4) Provide a low-particulate atmosphere, like that found in a clean room (accomplished with a HEPA filter that removes dust / particles from the glove box atmosphere).
Types of Controlled Atmosphere Glove Boxes:
I was interested in the first use listed above for electrodeposition of Al onto ITO glass. These glove boxes can be filled with either nitrogen or argon. Both satisfy the requirements of an ‘inert’ atmosphere for most applications, although argon is sometimes necessary (for a certain application I am unfamiliar with). There are three levels of glove box available for controlled atmospheres:
($2,000 – $4,000) (0.1% – 1% or 1 – 10 ppt (part per thousand)) Acrylic or polypropylene glove boxes that cannot hold a vacuum, but have two gas valves for flowing nitrogen or argon in and atmosphere out of the glove box are the cheapest option. They usually have a transfer chamber which also has two valves for purging the atmosphere. Be aware of chemical compatibility issues, acrylic cannot even hold up to acetone. Polypropylene is better, and sufficient for almost any application according to Cleatech LLC employees. Labconco claims that their Polyethylene glove box (in next price class) is even more chemical resistant, and would require strong solvents at high temperature to ever melt the material. Because you do not pull a vacuum, these glove boxes will not likely ever achieve oxygen concentrations below 1 ppt.
($7,000 – $10,000) (1 ppt) Acrylic, polypropylene, polyethylene, or stainless steel with tempered glass boxes, which can hold a vacuum fall into this category. They will achieve a lower oxygen concentration than just flowing nitrogen through the box, and will reach concentrations faster than the flow through method. However, because of the gloves on the box, in the main chamber you can only pull a vacuum of about -4 inches water column, and only pressurize to +4 inches water column. This means you have to vacuum pump and fill the box about 100 times to reach 1 ppt. 400-500 iterations will bring you down to 1 ppm, but in about 10 min the box will return to about 1 ppt due to diffusion of oxygen through the gloves, unless very large quantities of nitrogen are flowed rather violently through the box (a building nitrogen gas line is necessary for this). The 1ppt level should be stable overnight, especially if glove port hole covers are used. (note: diffusion is thermodynamically driven by concentrations, and is different than leaks. It will happen even with the box under positive pressure.). A major advantage to vacuum capable systems is the ability to pump the transfer chamber (which has no gloves to worry about) down to 29.99 inches of vacuum. This is approaching the vacuum level of outer space, and allows you to even remove oxygen adsorbed to materials. For atmospheres of 1 ppm, one should leave an object in the transfer chamber under vacuum for 20 min up to a whole day to ensure that all the oxygen has diffused off the material being introduced to the main chamber. Liquid containers should be filled to the top to minimize head space, and then capped with a rubber stopper, aluminum seal, or twist on cap.
($20,000 – $50,000) (0.1 – 1 ppm) To maintain a 1 ppm atmosphere for more than a few minutes or an hour, a scavenger system is necessary. This is a $10,000 system that actively pumps the glove box atmosphere through a series of filters that remove oxygen and humidity from the atmosphere.
Used Glove Boxes:
Chemical contamination from previous use is the he main concern about used glove boxes.
Companies / Products to Consider:
VWR has good prices and a good selection of Labconco glove boxes. (steel+glass, vacuum capable, ~$7,000-$50,000)
mBraun and Vacuum Atmospheres also carry a line each of glove boxes. (steel+glass, vacuum capable, ~$10,000 – $50,000)
Cole-Parmer and Fisher carry Plas-Labs glove boxes. (Acrylic, vacuum capable + scavenger system, ~$20,000)
eBay carries CleaTech LLC glove boxes, or you can get them direct. (Polypropylene, not vacuum, $2,000-$4,000)
I purchased the Chemical Resistant Polypropylene Glove Box for Labs W/ Nitrogen Ports and Airlock from Cleatech LLC. Many of their products are shown here on eBay.
LabX carries Safe-T-Dome. (Acrylic box that is very small and portable, not vacuum, uses a bladder to purge the atmosphere via displacement. $1,000 -$3,000).
O2 Sensor / Analyzer:
These cost thousands of dollars to reach sensitivities near 1 ppm. Therefore glove boxes rarely come with them (unless >$20,000), but rather they are used to rate a glove box design in factory, and then you just assume that you have the atmosphere the box is rated for. I found a “ToxiREA O2 Sensor” at Cole-Parmer with sensitivity 0.1% for $271.00, which should be suitable to ball-park 1 ppt concentrations in cheap glove boxes.