Primary Containment Flashcards
What type of filters do most BSCs use? What is an exception?
Most use HEPA filters in exhaust and supply.
Exception is Class I BSC, which only has HEPA-filtered exhaust.
What particle size do HEPA filters and ULPA filters remove?
HEPA: Most Penetrating Particle Size of 0.3 um with min efficiency of 99.99%.
ULPA: MPPS of 0.1-0.2 or 0.2-0.3 um with minimum efficiency of 99.999%.
Particles larger and smaller are removed with greater efficiency.
What do HEPA and ULPA filters not trap?
Neither traps volatile chemicals or gasses, only particulates.
When are ULPA filters used?
Can be used in BSC, but not currently a specific situation that requires them. More expensive to purchase, can raise energy costs, and can be detrimental to lifespan of device motors due to increased resistance through filter.
What are HEPA filters commonly made of?
Borosilicate medium, separated by aluminum.
Why must filter integrity be tested when a BSC is initially installed and each time it is moved or relocated?
Careless handling of the filter can result in tears or shifting of the filter, resulting in leaks in the medium.
Describe a Class I BSC, including airflow, ducting, what it protects, and if nonvolatile toxic and volatile toxic compounds can be used.
Airflow: 75 lfm
Duct: Direct to building exhaust OR recirculated if integral exhaust fan and no hazardous gasses or vapors OR canopy connected if integral exhaust fan and alarm when hazardous gasses and vapors used
Protection: Environment and personnel, NOT product
Nonvolatile Toxic: Yes
Volatile Toxic: When exhausted outdoors
Class I BSC
What are the types of Class II BSCs? Who do they protect?
Types A1, A2, B1, B2, and C1
Protect personnel, product, and environment
What distinguishes A1, A2, and C1 BSCs from B1 and B2?
A1, A2, and C2 - Recirculated air or discharged via canopy/thimble. Canopy if using volatile toxic chemicals.
Never connect to building exhaust.
B1 and B2 must be direct connected to building exhaust.
Describe a canopy/thimble.
For Class II, types A1, A2, and C1
Exhausts air to outside. Has a 1in gap to temper the pull of the building exhaust and prevent escape of contaminated air into room.
Why would a canopy/thimble be used?
Fluctuations in air volume and pressures in building exhaust systems make it difficult to match the airflow requirements of the cabinet.
Describe Class II Type A BSC. What differentiates A1 and A2?
Airflow: 75 lfm (A1) or 100 lfm (A2)
Duct: Recirculated to room OR to outdoors via canopy for volatile toxic chemicals or radionucleotides
Nonvolatile Toxic: Small amounts (A1), Yes (A2)
Volatile Toxic: Small amounts (A1), when exhausted outdoors (A2)
Class II Type A
Generally, where does downward moving air in a BSC split?
Split generally occurs halfway between front and rear grilles and two to six inches above work surface.
Describe a Class II Type B1.
Airflow: 100 lfm
Duct: Direct to building exhaust
Nonvolatile Toxic: Yes
Volatile Toxic: Small amounts, towards back of cabinet
What percentage of air is circulated vs recycled in a Class II Type A BSC?
70% recycled, 30% exhausted
What percentage of air is circulated vs recycled in a Class II Type B1 BSC?
30% recycled, 70% recirculated
Class II Type B1
Class II, Type B1 Benchtop
Describe a Class II Type B2 BSC.
Airflow: 100 lfm
Duct: Direct to building exhaust
Nonvolatile Toxic: Yes
Volatile Toxic: Small amounts
Total exhaust, no recirculation. Expensive to own and operate (higher air pressure requires heavier gauge ductwork and higher capacity exhaust fan), use should be justified.
Why must consideration be given to the chemicals used in BSCs?
As some chemicals can destroy the filter media, housings, and/or gaskets causing loss of containment.
Describe a Class II Type C1 BSC.
Airflow: 100 lfm
Duct: Recirculated to room OR direct connected to building OR canopy connected exhaust. Toxic volatile work at the back of the hood.
Nonvolatile Toxic: Yes
Volatile Toxic: Small amounts
How are Type II Class B1 and C1 BSCs similar and different?
Both have a special region of the work area intended for work with volatile toxic chemicals. However, C1 has a internal exhaust blower that allows the BSC to be room recirculated (no volatile toxic chemicals) or canopy-connected (if volatile toxic chemicals)
What percentage of airflow is recycled and exhausted in a Class II Type C1?
30% recycled, 70% exhausted.
Class II Type C1, Connected
Class II Type C1, Not connected
Describe a Class III BSC.
Gas tight. Exhaust is double HEPA or HEPA + incinerated. Pass throughs: dunk tanks, double door box (anteroom, autoclave). Full length rubber cloves.
Needs to be direct-connected to an exhaust system where the fan is separate from the exhaust fans of the facility ventilation system. Air kept at negative pressure
How gas tight must a Class III cabinet be?
No leak greater than 1 x 10 ^ -7 cc/second with 1% test gas at three inches pressure water gauge.
Class III
Laminar Flow Clean Bench/Vertical Laminar Flow Clean Bench
What does a laminar flow clean bench/hood provide?
Product protection
