Cleanroom Pass-Through Chambers FAQs
How does a pass-through enhance cleanroom operations?
Pass-through chambers reduce cleanroom foot traffic, the single largest source of particulate contamination and a significant operational expense. Instead of garbing up and carrying an object into the cleanroom, you simply transfer it through the pass-through chamber.
Interlocked pass-throughs prevent cross-contamination of adjoining spaces during this transfer by ensuring that only one door at a time can open. Various interlock designs enhance cleanliness and reliability.
What are my Interlock choices?
- Conventional Mechanical Interlock: standard mechanical interlocks attach to the chamber interior and engage (lock) one door as soon as the other opens. This is a reliable design but creates cracks that are hard to clean or sterilize. Conventional interlocks also create an internal clearance obstruction and are subject to damage if an operator applies too much force to the interlocked door.
- Isolated Mechanical Interlock: In double-wall pass-throughs, the interlock is mounted outside the transfer chamber, leaving interior surfaces smooth and easy to clean. Double-wall construction also adds to the rigidity and durability of the pass-through chamber. Like other mechanical interlocks, though, they provide no clear indication of when the opposing door is open or ajar.
- Electronic Interlock: As long as power can be furnished to the chamber, an electronic interlock provides optimal cleanliness and operational versatility. Terra’s electronic interlock (a feature of all Smart Pass-Throughs) include LED status alerts on both sides of the chamber, letting operators know when the opposing door is open or ajar and thereby preventing effort to force, and potentially break, the interlocked door.
Electronic Smart Pass-Throughs introduce many other optional capabilities: access control and logging, HEPA air showers to remove particles from samples, sample presence sensing, refrigeration and more (see information on Smart Desiccators under Terra’s Electronic Pass-Through section).
How are Pass-Throughs installed?
Terra’s ValuLine and General Use Pass-Throughs use retaining brackets to hold the chamber to the wall. The bracket on the clean side is welded to the chamber. The one on the opposing side slides onto the chamber and fastens to the wood or metal framing that surrounds the wall cut-out.
Terra’s CleanMount® Pass-Throughs employ a unique clamping system that requires no penetrations in the cleanroom walls and mounts in just a few minutes. As long as the wall cut-out is finished and sealed, you can quickly install or remove the pass-through without a costly cleanroom shutdown and re-validation.
To perform maintenance without contaminating a classified space, you first seal off the “dirty side” with plastic sheeting to maintain the positive-pressure differential. Loosening two lag bolts lets you lift the pass-through out of the wall without contaminating the room. Once out, the pass-through can be serviced, modified, or even replaced with an upgraded version to accommodate new applications.
Are Terra Pass-Throughs flush- or center-mounted?
Terra offer designs for both requirements. The CleanMount® system mounts flush against the cleanroom wall to eliminate particle accumulation and simplify cleaning. Flush-mount chambers protrude into the “dirty” side room and can be braced, if needed; Terra provides supports for this purpose. Alternatively, chambers can be specified for center-mounting in nearly any wall thickness. Electronic pass-throughs can even be specified with access doors on adjacent corner walls.
What makes a pass-through suitable for clean and sterile applications?
All CleanMount pass-throughs include an isolated interlock and smooth, coved corners for smooth internal surfaces that are easy to clean and sterilize. Doors feature a lift-off design for easy removal and cleaning, and 304 or 316L stainless steel surfaces stand up to common cleaning agents, including IPA. Terra’s ergonomic LiftLatches operate without metal-on-metal scraping inside the chamber, a common source of contaminants with rotary-style latches.
For the most demanding sanitary applications, specify a BioSafe® Pass-through, which adds an elastomeric door seal to the removable doors, making them autoclavable. All chambers can be electropolished upon request.
How can I extend the service life of my pass-through chamber?Specify replacement doors.
Terra's pass-through chambers last indefinitely, much longer than our standard product revision cycle. Pass-Through doors, however, are subject to damage, and ordering a legacy replacement can be costly and disrupt cleanroom operation. To avoid these problems, order replacements at the time you purchase the pass-through chamber; simply add "-RH" (for right-side hinge) or "-LH" (for left-side hinge) to the part number of the chamber.
How can I optimize a Pass-Through for parts access?
Terra offers several shelf and tray options for transferring and organizing small parts, including BioSafe® removable rack and tray systems and slide-out shelving.
For transfer of carts, bulk material containers and other large equipment, Terra Standard Sizes up to 72”W x 84”H. Customer may customize dimensions as needed.
Do Pass-Throughs meet UL requirements for fire-rated walls?
Terra offers several pass-through configurations with doors that bear the UL-10B label for 90-minute fire exposure, suitable for a 2-hour fire wall rating. Models are available with and without viewing windows, in chamber sizes up to 33”W x 36”D x 45”H.
How else can I protect delicate samples in a Terra Pass-Through?
HEPA air showers remove particles from sample surfaces before they enter the cleanroom. Ventilation units are also available to duct fumes that might be present in a sample, allowing the pass-through to act as a drying system.
For biological applications, a UV-C lamp with safety circuit kills or neutralizes microbes, including viruses and mold spores, before sample transfer into a sterile lab.
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