While a Class 10 cleanroom is designed to maintain low levels of pollutants, sometimes more rigid atmospheric control is called for within a cleanroom space to best fulfill a process or application. When it’s beneficial to have a microenvironment free of oxygen or water vapor within the cleanroom, a glove box can be customized and integrated to create the desired inert atmosphere with an automated gas management system — all in a way that meets Class 10 standards.

These modern gas management systems displace oxygen and moisture within a glove box or other hermetic enclosure using inert gas, such as argon or nitrogen, to create an ideal environment for various production and research processes that would adversely react with oxygen or moisture, commonly found in the air we breathe. Even better, the best gas management systems can reclaim and recycle the argon or nitrogen, for reuse within that enclosure. 

This contemporary “clean box” technology allows current cleanroom users to expand processes and fulfill new research applications within existing facility space. Wherever it would be helpful to have a hermetic enclosure with an environment of less than one part per million (ppm) oxygen and water vapor, a glove box with a gas management system can be installed — even when space seems too tight. All it requires is a little creativity and know-how. 

Identify and eliminate the culprits

Glove boxes have long been used to protect processes, or the person conducting the process. When specifying a glove box with a gas management system for a cleanroom, a delicate balance must be achieved to maintain the required protection, while concurrently complying with laminar flow and other cleanroom standards.

Gloves constructed of CSM are generally preferred and provide adequate safety for the glove box user under most conditions in or near a cleanroom environment. Image: Inert

To do so, it’s necessary to fully consider the following:

1) What applications will be performed within the glove box?
2) What glove box components may introduce unwanted particulates to the cleanroom?
3) How will everything be regularly cleaned?
4) What temperature is required?
5) Which is the desired atmosphere, in terms of oxygen and moisture levels?

With so much on the line, it’s helpful to engage a glove box engineer who can customize everything from the start of construction. Glove boxes can be manufactured from a variety of materials and finishes, but some present potential cleanroom problems from paint chipping, rust contamination, and corrosion. As such, the best choice is usually stainless steel number four.

Gloves constructed of soft Chlorosulfonated Polyethylene Rubber-Hypalon (CSM) are generally preferred and should provide adequate safety for the glove box user under numerous scenarios. Thinking proactively to when the gloves will be swapped out for normal wear and tear, a cleanroom glove box should be outfitted with an internal glove port cover to seal the environment and prevent any outside contamination. As a precaution, it is also recommended that once a new glove has been swapped in, the system should be purged to allow fresh inert gas to flush the working chamber and remove any atmosphere the new glove may have harbored.

Instead of an oil-based pump — which has the potential for spitting oil within a cleanroom — choose a dry scroll vacuum pump. The latter is cleaner, oil-free, and requires no maintenance, making it very cleanroom friendly.

Modern glove boxes employ advanced argon or nitrogen gas management systems to automatically displace and monitor oxygen and moisture levels to achieve a consistent <1ppm atmosphere. These systems also save on gas usage by recycling the gas rather than purging it. Image: Inert[/caption]

A cleanroom glove box should have radius corners and welded end panels to allow for ease of cleaning. It’s also common to use button studs as opposed to acorn studs, for the same cleaning ease.

The sealing gaskets of a glove box are integral to maintaining inert atmosphere integrity, and a faulty sealing gasket can easily leak unwanted particles into the cleanroom. As such, it’s important to specify sealing gaskets according to the details of the application. For example, some chemicals and solvents will degrade certain gasket materials more rapidly.

An insulated skin can be attached to the glove box to maintain a specific temperature.

Any particulates that might be generated from within a properly maintained glove box gas management system should remain in the system’s closed loop and eventually be exhausted outside the cleanroom. Similarly, when any components of a gas management system might prove too difficult to clean, the entire gas management system can be housed outside the cleanroom.

[caption id="attachment_126108" align="alignnone" width="800"]Programmable Logic Controllers (PLC) on today’s modern gas management systems provide real-time display of atmospheric conditions and automated control. They also collect perpetual data, providing reliability and lot traceability assurance, as well as long-term efficiency analysis. Image: Inert

Optimizing small spaces

When cleanroom space seems too tight to add a glove box and gas management system, it’s time to look at the facility’s building plans and get creative!

If there’s space for the glove box inside the cleanroom, but not the gas management system, the system can be installed next door, in a service hallway or maintenance room — or even on the roof— as long as all connectivity is within cleanroom standards, usually calling for stainless steel piping and stainless steel-finished tubing.

When items need to be moved in and out of the glove box without contact to the cleanroom atmosphere, an antechamber can be fixed into the wall of a cleanroom. It is also possible to have an antechamber automatically refill after the outlet to ensure that there is no contamination entering the antechamber.

The latest clean box technology

As research has progressed in industries such as biochemistry, pharmaceuticals, and organic light-emitting diode production, so has glove box technology. Gone are the days when it was necessary to manually purge a glove box with inert gas dozens of times a day with a mere hope of achieving an air-free atmosphere, or using a gas management system that only promises <10ppm oxygen and water vapor. That may have once been the industry standard, but many of today’s applications demand a constant <1ppm to maintain integrity of product and process.

The best of today’s automated glove box gas management systems take away the guesswork, reduce inert gas consumption, and provide a truer air-free atmosphere — just about anywhere you want it — allowing for new, ultra-efficient work cells throughout research and production facilities.

Daniel Clay is president of Inert, an engineering and manufacturing company in Amesbury, Mass., that produces inert atmosphere gloveboxes, gas management systems, and solvent purification systems. daniel.clay@inerttechnology.com; www.inerttechnology.com