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Lean Isolation Workstation Lean Isolation
 Selecting the best isolation system for pure, effective processing 
Sub vs. Drum:
Which isolation technology would be more effective for your process?
120 Liter Drum
The submarine is an amazing barrier isolation system, with heavy steel walls that block radiation, gas diffusion and nearly everything else.  It is equipped with environmental controls and instruments as well as lighting and other support for conducting work inside.  The drum can contain 120 liters while blocking leakage inward or outward at modest pressures orders of magnitude lower than the Sub; it has no internal support for work inside or observation of inside processes, and is highly permeable to electromagnetic and acoustic radiation, and some gasses.  Clearly, the sub isolates far more than the drum.

So why can you complete a sterile process in an hour in the drum while it fails in the submarine after weeks of effort by a large team?  The problem with the submarine is that there is too much inside the isolation space to control or decontaminate; we can isolate contents from the outside, but the microbes, chemicals and complex systems inside are another matter entirely.  The flanges, plumbing, control panels and light fixtures in the sub are practically impossible to fully clean and decontaminate.  The motors, communication devices, people, food and material stores are all sources of contamination, and well beyond decontamination.  The drum will require new openings or removal of caps to access the inside, but it can be cleaned in 15 minutes.  The submarine is contaminated before the first crew arrives and cannot be sterilized in weeks without destroying it in the process.
Laboratory glassware is the leanest and most common isolation for routine processing, but often more access or control is required.   When barrier isolation is needed there are usually advantages to added features, so "mission creep" is typical.  Practical impact of this isolation cabinet overkill is great, so the risk of error, project delay and contamination pose a real threat to project success
When processing in an isolated system, the potential for error, contamination and delay is always important, so long as the second law applies:
The second law of thermodynamics:
Disorder (entropy) increases in a closed system
As researchers, process engineers and technical project managers strive to avoid disorder, including contamination, measurement error, and environmental drift, they often consider Chaos theory, the Law of Unintended Consequences and Murphy's Law, as ways to apply the second law to challenges of barrier isolation work-space management.  If the technology manager is to avoid the consequences of mission creep leading to a chaotic failing result, they must choose simplicity over complexity whenever possible, and pay close attention to these classic challenges:
  • Every moving part increases probability of mechanical failure
  • Every sensor introduces drift, inaccuracy and risk of error
  • Every control system has feedback errors, and potential for instability and overshoot
  • Every nook, cranny, seam, fixture, corner or cavity is a potential reservoir of contamination
  • Every penetration, port, hole or cable-way adds risk of leakage
  • More surface area increases probability of residual contamination
  • Error and contamination sources are cumulative
  • Each element that adds risk also increases need for management and maintenance effort
The Lean Posi-Dome I-Box W
The Posi-Dome I-Box W offers a general purpose solution to the barrier isolation problem.  It provides user access, intervention and basic atmosphere control capabilities like other isolation enclosures, but otherwise, it is simple, reliable and easy to maintain, more like the Erlenmeyer flask.  It provides a path to clean, isolated processing, including required basic controls, without the invitation to mission creep inharent in larger highly instrumented units.  Compare Posi-Dome I-Box W to a heavy glove box with dry train processing:
Technology > Posi-Dome I-Box W
Lean Isolator
Heavy Glove Box
with Dry-Train


Configuration >
----------------------------------------
Design/Performance
Parameters
V---V
Critical moving parts 5 (one is redundant) 35+
Barrier wall technology Polymer clam shell Stainless steel & tempered glass plates: welded and/or bolted
Critical wall parts count 3 52 to 86
Manufacturing processes Plastic Thermoforming, CNC routing, drilling & manual assembly Torch cutting, bending brake, drilling, milling, welding, broaching, grinding, glue bonding/sealing, electronic assembly, wiring, calibration, programming, pipe-fitting, press fitting, painting/coating & manual assembly
Inside surface area 1.2 sq meters 3.7 to 9.8 sq meters
Electronic sensors 0 5 to 14
Purge pressure range 0 to 0.05 bars (guage) -0.995 bars to +0.2 bars (guage)
Primary pressure instrument manometer (bubblier) magnehelic (guage)
Pressure control system liquid-gas trap (bubblier) & weighted bellows electronic sensor, control valve
with microcomputer control & alarm system
Contaminant control level 0.2% to 400 PPM of O2, H2O or other contaminants 200 PPM to under 200 PPB of O2 or H2O
Contaminant control process initial purges + continuous trickle flow of purge gas automated chemical treatment loop with O2 sensors, H2O sensors, heaters, control valves and computer controls
Reliability:  MTBF >7000 hours 30 to 300 hours
Calibration / Certification by user - 15 minutes by qualified instrument mechanic 90 min to 4 hours
Maintenance required < 20 min per year 1 to 3 hours per month

For other perspectives about lean isolation you can review articles that mention Posi-Dome to see evaluations from Posi-Dome users. Here are links to two of them:

Lean Isolation Workstations Increase Empirical Success, (The Journal of Industry and Technology - Industrial Analytical Instrumentation Euro Technology) http://www.thejournalofindustryandtechnology.biz/page211.html

Right-sizing isolation for superior experimental results, (Laboratory Design News) https://www.labdesignnews.com/article/2016/11/right-sizing

Posi-Domes empower technologists past tough process challenges across five continents:
  • Portable Posi-Dome I-Box equipment provided inert conditions for Ocean Optics spectrometer demonstrations in Florida
  • Linkam Instruments uses it for clean isolation to complete precision work on optical instruments (near London)
  • In West Africa Posi-Domes provided aseptic conditions for an urgent Ebola drug trial managed by University of Oxford
  • Taiwan University of Science and Technology uses it for electrochemical testing in an inert atmosphere
  • In Western Australia Posi-Dome is used for sterile processing of fungal cultures
  • Acree Technologies in California conducts laser component coating research in an Argon filled Posi-Dome
If you search the web for articles about Posi-Dome you will find reactions and comments from some of these and other Posi-Dome users.
Posi-Dome™ I-Box W

Posi-Dome™ I-Box W

Special Atmosphere Workhorse
Posi-Dome™ I-Box W
Posi-Dome™ I-Box W Front ViewPosi-Dome™ Pressure ControlPosi-Dome™ I-Box W Top ViewLow pressure displacement purgePosi-Dome™ I-Box W on Low Profile base
Click to enlarge image(s)
Posi-Dome I-Box W "World" glove box isolator supports Nitrogen, Anaerobic, Hypoxic or other special atmosphere processing using Posi-Dome™ pressurized glovebox isolation. With fail-safe containment for a reliable special work environment; this glovebox cabinet is barrier isolated for positive pressure isolation. The positive pressure system is user-friendly, human engineered, healthy and energy efficient. Ready for use in laboratory, shop or field applications for inert gas and special atmosphere applications when connected to a regulated Nitrogen, or other gas supply (user furnished). This World model is ideal for batch experiments or processing anywhere.  For flexibility in laboratory and field use, this unit includes both a deep bowl base (shown above) and a low profile base for use when portability or interior floorspace are critical..
Features Benefits
Transparent, Lab-Grade Polymer Dome Cabinet Rugged, High-visibility, Light-weight, Chemical resistant & Easy to clean, Requires no internal light source
Deep Bowl Base Rugged, Spill control capable, Extra work volume & headroom, Easy dome removal for cleaning or alternate use
Mechanical clamp bolts compress flange seal Efficient, simple isolation that supports positive pressure operation with low or no leakage
HEPA Filter Air Processing Efficient, Safe, Autocavable, Easy to replace, Economical, Lasts for months in normal use
22 mil Nitrile Gloves Rugged, Easy to clean, Bleach resistant, Quality checked & CE marked
Dynamic pressure control system Simple, efficient system reduces pressure spikes, minimizes gas usage and is ergonomically operator friendly
Low pressure displacement bladder purge system Efficient, safe, low-energy atmosphere exchange without loud, high-energy vacuum pump
Low Profile Base Rugged, Spill control capable, Extra floorspace, Easy dome removal for cleaning or alternate use

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