From experience, we realize that there are many questions surrounding the decision to use Flexible Containment Solutions. Some have obvious immediate answers while others often require explanation and and even background explanations. The answers often raise more questions that the user needs to address before going further. This Bulletin provides answers to common interests that do not require detailed explanations:
What if I have to install it in a hood?
Hoods do provide convenient ventilation exhaust, but aren’t a necessity. Unlike Rigid Gloveboxes and Air Curtain approaches, Flexible Enclosures do not require ventilation because there are no windows or attachment gaskets to seal. The only non-heat sealed component is where external sleeves have coupling ring for attaching gloves. Most users find that letting enclosures merely breathe under applied stresses (temperature and pressure variations) is adequate. The interior is protected by a porous filter that allows clean air to both enter and leave. These filters have a better performance than Ultra High Efficiency Particulate Air (UHEPA) filters when functioning in this passive mode.
What if I don’t have much space?
This is a common concern that is easily alleviated, especially when it comes to hood space. Rectangular Flexible Enclosures, and Glovebags in particular, are usually designed as freestanding enclosures. With containment factors of typically >1010, they can be relied on to protect both the operator and the environment when set up outside a hood. This also means that they are mobile. They can be designed for laboratory bench use, or any flat surface, thereby conserving bench space. Needed utilities such as electrical, air purge, or data connections, can be accommodated using robust disconnect cables and a small compressed air cylinder or self powered air-pump. Using a cart with a flat surface, they can be either self-inflatable with an anchored system along the base, or requiring an external support frame installed on the cart.
Rigid internal frames will present a disposal problem.
What if it takes more than one operator to perform the operation?
When used on an open bench, a Rectangular Enclosure presents four sides and the top to which attachments, including glove sleeves, are usable. A Cylindrical Enclosure presents the entire perimeter wall for mounting sleeves, i.e. 360° horizontal access, as well as the top surface, provide the greatest access. Such instances can occur when packaging requires the use of special bagging closures, or operations require the separation and lifting of bulky vessels. In Kilo-scale development laboratories this is often a necessity. Using air inflatable enclosures increases their utility.
Cylindrical Enclosures have been used for changeout of both wet and dry process filters since first developed 1996. Their use ranges from inline liquid filters to the large exhaust-air filters used in emissions control from product dryers. When air-inflated enclosures were developed in 1998 they quickly became the choice liquid filter change-out enclosures purchased from the manufacturers.
What if I need good lighting?
Flexible Enclosures solve the problem experienced when using enclosed hoods or Rigid Containment. The same solution used for operator access solves the lighting problem. The flexible material typically has >95% combined light transmission into and out-of an enclosure. Unless enclosed within a hood, room lighting is usually sufficient for most users. Supplemental lighting will not affect the film opacity. While an opaque film is used for glove-sleeves, clear film is used for the structure and pass-through sleeves. This provides outstanding viewing capability for the operator. Any optical distortion created by a slack film surfaces can be resolved during use by flexing the film to stretch it flat.
What if I don’t have a convenient exhaust trunk?
Enclosures can be used on an open workbench without need for exhaust. Even when organic vapors and fumes are generated within the enclosure, they can be vented using a combination particulate + organic vapor filter. Under extreme conditions, a filter doghouse can be used to direct emissions to an appropriate exhaust snorkel.
What if I need containment in several areas?
Freedom to move a cart mounted flexible enclosure offers several advantages. It can be set-up and stored in an unused storage area until needed. There is no limitation on where it can be used – keep spares around! When already in use, it can be moved along open access areas such as hallways, and even shipped to other buildings and sites without unloading or disturbing the contents, e.g. cages containing quarantined animals.
Bag-in/Bag-out sleeves, or zippered airlocks, for transfer of large items such as cages enhances their versatility.
What if I want to quarantine animals?
Flexible enclosures are well adapted for use in animal rooms if manufactured with polyurethane which does not emit vapors. Room temperature sterilization procedures may be used for in-situ decontamination. Exhaust air can be filtered using a combined particulate/organic vapor filters which eliminates odors. An adjacent pass-through can be purged before opening to admit feed, water, and treatments. Disposal is the same as any flexible enclosure using encapsulation and pet litter to soak up animal wastes in preparation for collapsing and incinerating.
Terminal animals can remain in the enclosure for incineration as red bag waste. There is no risk of cross contamination. Multiple flexible enclosures can be used in a common quarantine area expanding the animal handling capabilities. Record keeping is greatly simplified.
What if my process evolves vapors and fumes?
Inherent film properties allow for generation of significant amounts of internal volume increase. The vent filtration can be designed to efficiently scrub many common gases. They also scrub fumes effectively when allowed to breathe, i.e. no forced airflow. This will allow use on an open bench.
When using forced airflow for inerting, the venting characteristics are equivalent to HEPA performance which requires either a snorkel exhaust over the vent filter or use in a hood.
Emission of solvents which can damage the film at high concentrations are accommodated using airflow dilution within the enclosure. This same approach is also used to ensure that the solvent/oxygen mixture is lower than the explosive limit, with <4% oxygen concentration being the safe level adopted for many processes. This Is the Lower Explosive Limit (LEL) for elemental hydrogen.
What if I need a data connection and/or utilities?
Small pass-throughs are be sealed into the enclosure for cable passage. For portability, short cable lengths having appropriate end connections allow an enclosure to be moved and reconnected within a facility.
What if my process generates heat?
Judicious choice of construction material provides capability for a skin temperature of up to 200°F for short duration and a working temperature up to 180°F. Connections exceeding this, e.g. a vessel port or dryer discharge, a steel bridging connection can be used as a buffer. Flexible films should not be used in environments for hot materials contact, especially for long contact with hot powders and liquids.
What if I have to enclose my entire process?
The first question is why? The question typically arises when retrofitting a facility for long term production. It is usually best to enclose seal points individually. This approach has the advantages of:
- unlimited access
- ease of visual inspection and adjustment
- identification of leak points in need of further improvement
- elimination of enclosure cleaning (and attendant procedures with extensive operator training)
- not necessarily needing attention from a current Good Manufacturing Practices (cGMP) perspective.
The use of sorbent pads within an enclosure allows observation of intermittent liquid releases. Bag-over-bag changes can readily be performed in place without process interruption.
Full enclosures may be necessitated when an existing equipment train is needed for pilot scale purposes, e.g. a tableting or dosing machine . These can range in size from containing a single piece of equipment eliminating the need for an operator to enter the enclosure, to a full scale multi-room enclosure with gowning, decontamination and degowning, storage doghouses, process feed lines, formulation and filling, and packaging of raw and final product handling.
Once installed, an entire enclosure can function as a semi-permanent installations with an integral clean room. FabOhio, Inc. can advise on fully tested systems that allow an entire enclosure, including the ceiling and exposed equipment, to be cleaned without operator presence and generating a minimal amount of cleaning waste.
What if I need to add materials during the process?
This is readily accommodated using either a robust zippered airlock or a pass-through sleeve designated for materials addition. Product, tools, and waste are handled in the same manner.
What if I am doing wet processing?
Water and solvent supplies and waste capability can be incorporated into Flexible Enclosure design. Stirring equipment and even heating devices can be enclosed as long as thermostatic control is incorporated. Voluminous release of water or solvent vapor is subject to the controls mentioned above. Increased ventilation is advised to prevent saturation of the exhaust filter(s). Inerting is used to achieve <LEL concentrations of vapors and air.
What if our waste handling procedures require drumming of solid waste having <1% free liquid?
Flexible enclosures do not require decontamination before disposal. In-place encapsulation procedures have been developed which create a minimal amount of liquid waste, e.g. <10ml to encapsulate a 6ft X 4ft X 4ft enclosure and its contents (unless large quantities of free powder are involved. If this amount of liquid is unacceptable, it can be absorbed using readily available pet litter.
What if our equipment is too big, e.g. a two story structure?
There are few limits to the size of a Flexible Enclosure. Two-story structures such as pan dryers, and pizza-oven dryers have been fabricated. Similarly, horizontal suites having multiple rooms, and 90° connections have been used (see the drop-down items on this web-site).
What if I don’t know what I need?
A containment engineer having expertise in Flexible Containment should walk you through your process to come up with the optimum design at the most reasonable cost for your purpose. The issues already discussed come into play to ensure you have a reliable workable solution. Such experts have access to databases covering materials of construction properties, materials compatibility, durability, and already existing designs used in similar operations. This allows the user to quickly develop, or adopt, a design which can be tested in use as a prototype for both operator buy-in and training, and production purposes. Most users benefit from testing a prototype before making optimum changes for a production model without excessive cost.
Without access to such databases, a flexible containment project can costs several thousands of dollars, instead of the hundreds of dollars typical of FabOhio, Inc. costs for a delivered solution.
What if I have inexperienced operators?
Operator training is less arduous than is required for Airflow or Rigid Containment control. The basic criteria are the same as for any gloved operation – no jewelry, think before you doing, etc., i.e. common sense. The one uncommon issue is gloved entry and exit, experiencing slight resistance which is rapidly accommodated by the Flexible Enclosure. An operator can be effectively trained and qualified within minutes.
What if I have a limited budget?
Flexible Enclosures are the only feasible method to achieve containment capability in a short time frame – typically <4 weeks after design acceptance, without expensive and time consuming design requirements, and even without a purchase order being generated. Many clients purchase using a credit card – personal and company!
What if I do not know what the design criteria are?
This is where your expert adviser has the greatest value. From experience they will know what works best for a particular need. Materials selection is the most critical decision due to differences in film properties. Engineers conventionally design enclosures with precise measurements which is inappropriate for Flexible Enclosures. The films are pliable and will readily stretch without losing their inherent physical properties. Dimensional stability is rarely an issue since most mounting techniques can accommodate small changes. Customers having knowledge of Flexible Containment usage frequently submit designs on the back of an envelope or napkin, relying on the fabricator to optimize the design.
Choice of fabricator will determine the quality and usable life of an enclosure. The fabrication skills lie in knowing how to temper the film before submitting to the pattern cutter. The optimum way to cut the pattern. Proper stages in construction using a sealing process that ensures seals have the highest integrity – especially where multiple film layers such as corners and inflation bladders, while maintaining their structural integrity. Particulate free enclosures are tested for integrity after fabrication and finally cleaned before overpacking for shipment. Radiation sterilization is also available using a qualified service at dosages established by a third party test laboratory (>1,000,000 sterilization factor using a standard battery of tests.
What if I do not know how to install and commission a flexible enclosure?
Frame construction and enclosure installation is a simple matter. Using PVC pipe purchased at a hardware store is ideal for prototype models which means that the support frame can be constructed at the user site before or after the enclosure is received. A frame for a simple enclosure costs <$60 which includes the price of a PVC pipe cutter. When advised by a Flexible Containment expert the process is simple. Alternatively a support frame made of PVC, laboratory aluminum struts and clamps, and even electropolished stainless steel can be constructed and shipped at placement of an order. Most effective construction is a simple PVC frame which can be easily adjusted during use to the ideal size and placement of corners etc. while testing a prototype. This allows for cart mounted enclosures which require mobility and clearance allowances. Once a final design is achieved the cosmetically preferred frame can be created for long term use.
Inflatable support enclosures can be in operation within minutes using a hand pump or low pressure air source. Frame mounted enclosures can be constructed, or assembled, and †he enclosure mounted and commissioned for use within a few hours. An experienced installer can have a ventilated multi-room enclosure suite functioning within 1 – 3 days after delivery to the site.
What if I don’t know who to call?
This is the easiest of all questions. First visit our website and check out the topics and images to get a feel of what’s already been used. Off the shelf products are few and often have to be modified for use. FabOhio, Inc. has found that a prototype preceding a final design test and volume purchase is the best way, and costs less than most providers stock and custom items. With collective experience exceeding 170 years we have addressed – and resolved, many customer issues. Our clients attest to our performance and integrity by returning over many years.