Cleanrooms and HVAC Systems Design...
Transcript of Cleanrooms and HVAC Systems Design...
Engsysco
Wei Sun, P.E.
ASHRAE Distinguished Lecturer
Society Technology Transfer Committee Chair (12-13)
“Clean Spaces” Technical Committee (TC9.11) Chair (07-10)
“Healthcare Facilities” Technical Committee (TC9.6) Member
“Laboratory Systems” Technical Committee (TC9.10) Member
IEST (Institute of Environmental Sciences and Technology) Society President
ISO 14644 Cleanroom Standards USA Delegate
Engsysco, Inc. President
Ann Arbor, Michigan, USA
Web: www.engsysco.com Email: [email protected]
Cleanrooms and HVAC Systems
– Design Fundamentals Belgrade, Serbia April 28, 2017
Cleanroom Design Considerations (Applications)
Semiconductor
Microelectronic
Pharmaceutical
Biotechnology
Aerospace
Automotive
Medical Devices
Optical Devices
Hospital
University Labs
Food Processing
Miscellaneous
Cleanroom - A special enclosed area, its environment typically has the following controlled parameters:
Temperature
Humidity
Sound and Vibration
Lighting
etc.
Common Requirements
Airflow Pattern
Room Pressure
Particle Contamination
(Airborne, Surface & Liquid-borne)
Microbial Contamination
(Airborne, Surface & Liquid-borne)
Electrostatic Discharge
Gaseous Contamination
Process Specifics
Special Requirements
Cleanroom Design Considerations (Controlled Parameters)
U.S. Federal Standard 209E
Airborne particulate cleanliness classes in cleanrooms and clean zones (former US standard, canceled in November 2001)
ISO Document
ISO-14644: Cleanrooms and Associated Controlled Environments
ISO-14644-1 Classification of Air Cleanliness
ISO-14644-2 Cleanroom Testing for Compliance
ISO-14644-3 Methods for Evaluating & Measuring Cleanrooms & Associated Controlled Environments
ISO-14644-4 Cleanroom Design & Construction
ISO-14644-5 Cleanroom Operations
ISO-14644-6 Terms, Definitions & Units
ISO-14644-7 Enhanced Clean Devices
ISO-14644-8 Molecular Contamination
ISO-14698-1 Biocontamination: Control General Principles
ISO-14698-2 Biocontamination: Evaluation & Interpretation of Data
ISO-14698-3 Biocontamination: Methodology for Measuring Efficiency of Cleaning Inert Surfaces
Cleanroom Standards in US (Previous US Federal Standard and Current ISO Standards)
FS 209 ISO 14644 FS 209 ISO 14644 FS 209 ISO 14644 FS 209 ISO 14644 FS 209 ISO 14644 FS 209 ISO 14644
Particles/ft3
Particles/m3
Particles/ft3
Particles/m3
Particles/ft3
Particles/m3
Particles/ft3
Particles/m3
Particles/ft3
Particles/m3
Particles/ft3
Particles/m3
1 10 2
2 100 24 10 4
1 3 35 1,000 7.5 237 3 102 1 35 8
10 4 350 10,000 75 2,370 30 1,020 10 352 83
100 5 100,000 750 23,700 300 10,200 100 3,520 832 29
1000 6 1,000,000 237,000 102,000 1,000 35,200 8,320 7 293
10,000 7 10,000 352,000 83,200 70 2,930
100,000 8 100,000 3,520,000 832,000 700 29,300
9 35,200,000 8,320,000 293,000
0.1 µm 0.5 µm 5.0 µm0.3 µm 1 µm
FS 209
Class
ISO
14644
Class
0.2 µm
These Two Standards Similar? (Comparison of FS-209E and ISO-14644 in Combined Table)
Air Cleanliness Class Definition Comparison
Between FS 209 and ISO 14644
1
10
100
1,000
10,000
100,000
1,000,000
10,000,000
100,000,000
0.01 0.1 1 10
PARTICLE SIZE, μm
PA
RT
ICL
ES
PE
R C
UB
IC M
ET
ER
S
ISO-1
ISO-2
ISO-5
ISO-4
ISO-3
ISO-6
ISO-9
ISO-8
ISO-7
FS-1
FS-100,000
FS-10,000
FS-1,000
FS-100
FS-10
These Two Standards Similar? (Comparison of FS-209E and ISO-14644 in Overlapping Chart)
They are NOT identical, but roughly equivalent under certain classes and particle sizes.
0.1
µm 0.2
µm 0.3
µm 0.5
µm 1
µm 5.0
µm
Cla
ss 1
Cla
ss 2
Cla
ss 3
Cla
ss 4
Cla
ss 5
Cla
ss 6
Cla
ss 7
Cla
ss 8
Cla
ss 9
1
10
100
1,000
10,000
100,000
1,000,000
10,000,000
100,000,000
Particle C
ount / m3
Particle Size (Channel)Cleanlin
ess Class
Cleanroom Particle Counts Per ISO Classification
Class 1
Class 2
Class 3
Class 4
Class 5
Class 6
Class 7
Class 8
Class 9
ISO 14644 Classification (Airborne Particle Sizes, Counts and Classifications in 3D Illustration)
Sources of Contamination
Description Control Methods
Infiltration through doors, and cracks at windows, and walls
Tighter exterior wall construction, exterior zone pressurization, vestibules at main entrances, and seal space penetrations.
Outdoor air
Makeup air entering through the air conditioning systems
Multiple level filtrations External
Indoor transfer air between rooms
Infiltration through doors, windows, and wall penetrations for pipes, ducts, etc.
Seal wall penetrations, multiple level pressurizations & depressurizations to obtain proper airflow directions
People
Largest source of internal particles: skin scales, hair, textile fibers
Garments, proper gowning procedures, air shower before entry
Work surface shedding
Rubbing one item against another
Use cleanroom suitable or rated furniture
Process equipment
Spray, painting, welding, grinding
Local filtration and exhaust
Raw and semi-finished material
During transport
Equipment washing, cleaning and sterilization before entry, use airlock & pass-through
Liquids, pressurized gases used in process
During preparation, processing and packaging
Local exhaust
Chemicals used for cleaning
Out-gassing to room Use cleanroom suitable or rated cleaners
Internal
Room construction materials
Dust generated from wall, floor, ceiling, door, fibrous insulation
Constructed with special building materials
Particle Sources & Control
Filtration Dilution Isolation
Utilizing HEPA & ULPA
filters to remove
particles from supply
air
• HEPA: >99.97%
(@ 0.3μm MMD)
• ULPA: >99.999%
(@ 0.12μm MMD)
Diluting internally contaminated air with filtered clean air
• Higher air change
rate, better dilution
Isolating particle generations with barriers, or removing directly from major sources
• Process exhaust
• Mini-environment
Airborne Particle Physical Controls
Control Methods
Physical:
• Heat
• Radiation
• Filtration
Chemical:
• Sterilization
• Disinfection
Unlike non-viable particles which can’t
reproduce, microorganisms could
reproduce at a rapid rate if nutrition and
environment are favorable.
Microorganism can be classified as
bacteria, algae, fungi, protozoa and
viruses. Some of these are essential,
and harmless, while others are harmful
and dangerous.
Microbiological Contamination & Control
As Built: Installation is complete with all services connected and functioning, but with no production equipment materials and no personnel present.
At Rest: Installation is complete with equipment installed and operating in a manner agreed between the customer and supplier, but with no personnel present.
Operational: Installation is functioning in the specified manner, with specified number of personnel present and working in the manner agreed upon.
ISO 14644 Standard Classifications –
Occupancy States
Pharmaceutical Grade
vs. Classification
Maximum P ermitted N umber of P articles P er m 3 ( equal to or above )
EU Pharmaceutical Cleanliness Grade
Cleanliness Classification
Grade At Rest In Operation FS 209 ISO
14644
0.5 µ m 5 .0 µ m 0.5 µ m 5 .0 µ m 0.5 µ m 5 .0 µ m
A 3 , 500
0 3 , 500
0
100 5 3,520 29
B 3 , 500
0
350,000
2,000
1 , 000 6 35,200 293
C 350,000
2,000
3,500,000
20,000
10 , 000 7 3 52 , 000 2 , 930
D 3,500,000
20,000
Not defined
Not defined
100 , 000 8 3 , 520,000 29 , 300
Recommended limits for microbial contamination in the operation state (average values)
Microbial Contamination Limits
In Operation
Operation
Design Requirements
USA FDA EU
Non-sterilized product or container
Particle cleanliness ISO 8 (Controlled Area)
Grade C
Maximum viable Organisms (cfu)
2.5/ft3 100/m3
Room Airflow 20 ACH or higher 15-20 minute clean-up time
Room Pressure 12.5 Pa Positive
Sterilized product or container
Particle cleanliness ISO 5 in ISO 7 Background (Critical Area)
Grade A in Grade B Background
Maximum viable Organisms (cfu)
ISO 5: 0.1/ft3 ISO 7: 2.5/ft3
A: 1/m3 B: 5/m3
Room Airflow 90±20 fpm 0.36 - 0.54 m/s
Room Pressure 12.5 Pa Positive
Control of Particles and Microbial Sterilized
and Non-sterilized Product
Class
US 209 ISO
Ceiling Filter Coverage
HEPA or
ULPA
9 5% - 15%
100,000 8 5% - 15%
10,000 7 15% - 20%
1,000 6 25% - 40%
100 5 35% - 70%
HEPA
10 4 60% - 90%
1 3 60% - 100%
2 80% - 100%
1 80% - 100%
ULPA
Typical Ceiling Filter Coverage
IEST RP-12.1 (Before 2007)
Room Airflow Volume/Quantity (Traditional Approaches: Table Methods)
Classification
ISO Class FS - 209 Class
Air Change Per Hour (ACH)
Range
8 100,000 5 – 48
7 1 0,000 6 0 – 90
6 1 , 00 0 150 – 240
5 100 240 – 480
4 10 300 – 540
3 1 360 – 540
2 360 – 600
1
Non-Unidirectional
(Conventional) Flow
Unidirectional
Flow
Mixed
Flow
Mini-Environment
Flow
Room Airflow Patterns
Ballroom Office and
Support
Areas
One Big
Cleanroom
Service Area
Service Area
Mini-Environment
Service Chase
Office and
Support
Areas Cleanrooms
Service Area
Service Area
C C C C
C C C C
Office and
Support
Areas Cleanrooms
Service Area
Service Area
R
R
R
R
R
Small
rooms
Multiple
Clean
R
R
R
R
R
Shared Return Air
Chase (TYP)
Mini-Cleanrooms
Less-clean
Cleanroom
Cleanroom Floor Arrangements
Raised Floor
Cleanroom
Submains
Chemical Supply Systems Process Supply Systems
Gas Cabinets
Basement
Perforated Slab Process Exhaust
Waff le Slab
Ceili ng + Filter
Pump
Scrubbed Exhaust Air
Fan Tow er
Return Air
Stair Case
Visitors Corr idor
Maint. Corr idor
Pressurized Plenum
Silencer
Cooling CoilMake-Up Air
Process Corr idor
ITRI
Pressurized Plenum (Fan Tower) Arrangement
Stair Case
Scrubbed Exhaust Air
Ret urn Air
SubmainsMake-Up Air Process Supply Submains
Basement
Scrubber
Cleanroom
Process Supply Syst emsGas Cabinets
4.8m
0.0m
3.6m
9.6m
4.8m
2.2m
3.5m
ITRI
Fan Filter Units (FFU) Arrangement
Scennario 1: Room Prerssurized
SA - (EA+RA) = ΔV = ΣQ > 0
Total Room
Supply Airflow
(SA)
Total Room
Exhaust and/or
Return Airflow
(EA+RA)
Room
Positively
Pressurized
+ To
tal
Ro
om
Su
pp
ly A
irfl
ow
(S
A)
To
tal
Ro
om
Exh
au
st
an
d/o
r R
etu
rn A
irfl
ow
(EA
+R
A)
Offset
Flow
ΔV
Total Leakage
Airflows
ΣQ
Particle Migration Control (Room Pressure Control)
Scennario 2: Room Non-Prerssurized
SA - (EA+RA) = ΔV = ΣQ = 0
Total Room
Supply Airflow
(SA)
Total Room
Exhaust and/or
Return Airflow
(EA+RA)
Room
Non-Pressurized
To
tal
Ro
om
Su
pp
ly A
irfl
ow
(S
A)
To
tal
Ro
om
Exh
au
st
an
d/o
r
Retu
rn A
irfl
ow
(E
A+
RA
)
Offset
Flow
ΔV = 0
Total Leakage
Airflows
ΣQ = 0
Particle Migration Control (Room Pressure Control)
Scennario 3: Room De-prerssurized
SA - (EA+RA) = ΔV = ΣQ < 0
Total Room
Supply Airflow
(SA)
Total Room
Exhaust and/or
Return Airflow
(EA+RA)
Room
Negatively
De-pressurized-
To
tal
Ro
om
Su
pp
ly A
irfl
ow
(S
A)
To
tal
Ro
om
Exh
au
st
an
d/o
r R
etu
rn
Air
flo
w
(E
A+
RA
)
Offset
Flow
ΔV
Total Leakage
Airflows
ΣQ
Particle Migration Control (Room Pressure Control)
Pressure differential can force particles to migrate
(in or out) through cracks on cleanroom enclosure.
Particles can migrate through cracks, such as minor leaks on walls,
ceiling, joints, duct/pipe penetrations, etc. and air gap between door
and frame, when a pressure differential exists across the cleanroom
enclosure.
CleanroomCorridor
ΔP=0Neutral
CleanroomCorridor
ΔP>0Pressurized
CleanroomCorridor
ΔP<0De-Pressurized
Why Do Particles Migrate (Exchange) Between
Cleanroom and Adjacent Area(s)? (1)
Particle concentration difference can force particles to
migrate (in or out) through cracks on cleanroom
enclosure.
Particles can also migrate through these cracks when a particle
concentration difference exists across the cleanroom enclosure due
to mass diffusion until an equilibrium is reached.
CleanroomCorridor
ΔP=0Neutral
ΔC= One-Class Difference
CleanroomCorridor
ΔP=0Neutral
ΔC= Two-Class Difference
CleanroomCorridor
ΔP=0Neutral
ΔC= Three-Class Difference
Why Do Particles Migrate (Exchange) Between
Cleanroom and Adjacent Area(s)? (2)
By two forces:
Under pressure difference (air movement by force)
Under particle concentration difference (mass diffusion)
Based on the combination of conditions, these two forces
could work in the same or opposite directions.
What is the combined effect?
The prevailing force determines the particle net gain or
loss through migration into cleanroom.
Particle Net Gain/Loss through Migration
CLEANROOM
AIRLOCK
+CORRIDOR
++
+++
AIRFLOW
CASCADING AIRLOCK
AIRFLOW CLEANROOM
AIRLOCK
+CORRIDOR
++
-
AIRFLOW
BUBBLE AIRLOCK
AIRFLOW
CLEANROOM
AIRLOCK
+CORRIDOR
- -
-
AIRFLOW
SINK AIRLOCK
AIRFLOWCLEANROOM
AIRLOCK
-CORRIDOR
++
-
AIRFLOW
AIRFLOW
- -AIRLOCK
DUAL COMPARTMENT AIRLOCK
Air Lock An intermediate room
between adjacent
areas with different
cleanliness to
minimize particles,
microbial and/or fume
migrations.
Type Cascading
Bubble
Sink
Dual Compartment
Particle Migration Control (Airlock)
Type of Cleanroom Selection of Airlock
Functionality of Airlock Relative Pressure Relationship
Positive pressure
No fume or bio agent
No containment needed
Cascading Prevent cleanroom being contaminated from dirty corridor air
Prevent cleanroom being contaminated from surrounding spaces through cracks
Cleanroom: +++
Airlock: ++
Corridor: +
Negative pressure
Has fume or bio agent contamination
Containment needed
Bubble Prevent cleanroom being contaminated from dirty corridor air
Prevent cleanroom fume or bio agent releasing to corridor
Cleanroom: -
Airlock: ++
Corridor: +
Negative pressure
Has fume or bio agent contamination
Containment needed
Sink Prevent cleanroom being contaminated from dirty corridor air
Allow cleanroom fume or bio agent releasing to airlock. No personal protective equipment is needed
Cleanroom: -
Airlock: - -
Corridor: +
Negative pressure
Has toxic fume or hazardous bio agent contamination, or has potent compound substances
Containment needed
Personal protection needed
Dual Compart-ment
Prevent cleanroom being contaminated from dirty corridor air
Prevent cleanroom fume or bio agent releasing to corridor
Personal protective equipment (such as pressurized suit and respirator) is required
Cleanroom: -
Neg. Airlock: - -
Pos. Airlock: ++
Corridor: -
Notes:
1. EXCESSIVE NEGATIVE PRESSURE IN CLEANROOM IS NOT RECOMMENDED, SINCE IF IT IS NOT SURROUNDED BY OTHER CLEAN SPACESS, UNTREATED DIRTY AIR CAN INFILTRATE THROUGH CRACKS INTO CLEANROOM.
2. COMMONLY A CLEANROOM SERVICE CORRIDOR NEEDS TO BE DESIGNED SLIGHTLY POSITIVE OR NEUTRAL PRESSURE, DO NOT DESIGN IT IN NEGATIVE PRESSURE UNLESS A DUAL-COMPARTMENT LOCK IS UTILIZED.
How To Select
An Airlock?
Answer questions
below:
Is the room in
positive or
negative pressure?
Has fume or bio
contamination?
If containment
is needed?
If personal
protection
is needed?
Particle Migration Control (Airlock Selection)
Pressure Stabilizer
A dynamic control
approach: Use an
pressure-adjustable
automatic relief damper
as a leakage regulator
to maintain a minimum
room pressure when a
door is opened.
Particle Migration Control (Pressure Stabilizer)
Flow Percentage Method (Example: VA Hospital Std.)
• Neutral: SA – (RA+EA) = 0
• Positive (+): SA - (RA+EA) = 15% of SA
• Positive (++): SA - (RA+EA) = 30% of SA
• Negative (-): (RA+EA) – SA = 15% of SA
• Negative (- -): (RA+EA) – SA = 30% of SA
Flow Differential Method (Example: CDC Guideline)
• Neutral: SA – (RA+EA) = 0
• Positive : SA - (RA+EA) = Min. 60 L/s (125 CFM)
• Negative : (RA+EA) – SA = Min. 60 L/s (125 CFM)
Problem with these rule-of-thumb approaches: Each room may
have different air-tightness on enclosure, a fixed offset value ΔV
without field adjustment capability could cause problem in
control.
Traditional Rules-of-Thumb Design Methods
Cleanroom often requires higher airflow rate to dilute room
contaminated air in order to lower particle concentration, so its
“airflow rate over cooling load” ratio is typically higher, or
much higher than a normal ratio range for commercial spaces
(CFM/Ton=300-500, or L/s/Ton=150-250).
Mismatch design (higher airflow rate to a relative smaller cooling
load) could cause a cooling coil to have a sensible cooling only
without latent heat removal which may result poor humidity
control inside cleanrooms.
For ISO Class 6 or cleaner cleanrooms, the flow rate/cooling
ratio may be beyond the reach of a single AHU unit can handle to
avoid mismatch, multiple air-handing systems (loops) are often
utilized to ensure performance and save energy.
Load Characteristic and Air Loop Selections (For Energy Conservation and Performance)
HVAC Schematic and Diagram (Primary Loop Alone Air-Handling System)
For ISO Class 7, 8, 9 (FS-209 Class 10,000, 100,000)
Typical Application:
CFM/Ton ratio: 300-500 (L/s/Ton ratio: 150-250)
RA
EA
SA
Q
OAOA+RASA
Space Impurity
Concentration
Exhaust
AirLeakage
Air
Particle Generation
Deposition
Cs
Space
D
G
Efficiency Ea
Supply
Air
Return
Air
Makeup
Air
Co
CeCs
Cs
H
C
FIL
TE
R
C
C
AHU Unit
HE
PA
Efficiency Eb
HVAC Schematic and Diagram (Primary-Secondary Loops Air-Handling Systems)
For ISO Class 4, 5, 6, 7 (FS-209 Class 10, 100, 1,000, 10,000)
Typical Application:
CFM/Ton ratio: 800-5,000 (L/s/Ton ratio: 400-2,500)
Primary flow/Secondary flow ratio: 2-10
RA
EAQ
OAOA+RASA
Space Impurity
Concentration
Exhaust
AirLeakage
Air
Particle Generation
Deposition
Cs
Space
D
G
Efficiency Eb
Return
Air
Treated
Makeup
Air
C1
CeCs
Cs
FIL
TE
R
Primary Fan Unit
H
C
FIL
TE
R
C
C
Secondary Makeup Unit
OA
Makeup
Air
Co
SA
Supply
Air H
EP
A
Efficiency Ea
Efficiency Ec
HVAC Schematic and Diagram (Primary-Secondary-Tertiary Loops Air-Handling Systems)
For ISO Class 1, 2, 3, 4 (FS-209 Class 1, 10)
Typical Application:
CFM/Ton ratio: 2,500-25,000 (L/s/Ton ratio: 1,250-12,500)
Primary flow/Secondary flow ratio: 2-10
Secondary flow/Tertiary flow ratio: 2-5
RA
EAQ
OA+RA2OA+RASA
Space Impurity
Concentration
Exhaust
AirLeakage
Air
Particle Generation
Deposition
Cs
Space
D
G
Efficiency Eb
Return
Air
Treated
Makeup
Air
C1
CeCs
Cs
FIL
TE
R
Primary Fan Unit
H
C
C
C
Secondary AHU Unit
OA
SA
Supply
Air
HE
PA
Efficiency Ea
Efficiency EcRA2RA1
H
C
FIL
TE
R
C
C
Tertiary Makeup Unit
OA
Makeup
Air
Co
Efficiency Ea
Treated
Makeup
Air
C1
Configuration-7: Fan-Filter Units For Primary Recirculation
Typical Application:
CFM/Ton ratio: 800-25,000
(L/s/Ton ratio: 400-12,500)
FFU flow/AHU flow ratio: 2-50
Room sensible ratio: high to very high
Air Handling Configuration Strategies 8 (ISO Class 1, 2, 3, 4, 5, 6, 7)
(FS-209 Class 1, 10, 100, 1,000, 10,000, 100,000)
Building Systems
City water & gas services
Cold/hot water distributions
Gas distributions
Storm, sanitary & vent
Fire pump & automatic sprinkler systems
Emergency power generator
HVAC & Indoor comfort
Building
management
Cleanroom HVAC&R
Make-up system
Recirculation system
Return air system
Temperature & humidity controls
Room pressure control
Airlock
Noise and vibration control
Hydronic heating
Comfort chilled water
Cooling tower water
Particle counting
Cleanroom Process
Gas detection
Static control
RO and DI waters
Process chilled water
Chemical gases and storages
Solvent drain and collection
Solvent gas exhaust
Process vacuum
Scrubbed exhaust
House vacuum
Acid drain and waste neutralization
Clean dry air
Instrumentation air & control
Process and Building Systems
FS Class 1
FS Class 10
FS Class 100
FS Class 1,000
FS Class 10,000
FS Class 100,000
Classification
ISO Class 1, 2 & 3
ISO Class 4
ISO Class 5
ISO Class 6
ISO Class 7
ISO Class 8 & 9
Wall System Aluminum Component
Aluminum Component or Metal Stud
Wall Panel Honeycomb Aluminum Conductive Finish Aluminum Polystyrene Core or Epoxy Coated Steel Laminated over Drywall
Vinyl or Epoxy Coated Drywall
Paint Epoxy
Epoxy / Latex Latex
Ceiling Grid 2” Aluminum Gel Seal Ceiling System
1½” Steel Gasketed
Grid Support All thread with Strut & Turn buckles
12 ga wire to grid, 10 ga wire to filter @ Corner of Grid Intersection Only
Floor Raised Floor with Perforated / Grated Access
Concrete Covered with Epoxy Solids or Sheet Vinyl
Air Return Floor Low Sidewall Low Sidewall or Ceiling
Typical Cleanroom Construction Materials
Selective Cleanroom Design Ideas (1)
ISO-5 raised-floor large ballroom design to meet processing requirements
Perforated concrete floor allows return air down to sub-floor area below.
Sub-floor area (below cleanroom) houses large process/utility equipment, ducts and piping.
Critical process located in a mini-environment (ISO-5) which is in an ISO-7 large cleanroom
Selective Cleanroom Design Ideas (2)
Return air floor panels’ arrangement to accommodate equipment footprints (ISO-7)
Shared return air chase could house some process piping and small equipment.
Small pass-through on door allows small items transport while minimize door operations.
Sliding doors have shorter cycle than swing doors to reduce contamination from corridor.
Selective Cleanroom Design Ideas (3)
CFD analysis of “velocity vector” around a moving door (second door of an airlock)
CFD to visualize particle migration from gowning room to airlock and to cleanroom
Roof storm drains collected for irrigation of landscaping
Solar panels on roof to supplement electricity usage
Unidirectional flow inside RAB Mixed flow in Room
Lower concentration inside RAB, higher
concentration near person due to recirculation air
Higher concentration near face
By K. Khankari 2013
Selective Cleanroom Design Ideas (4)
Selective Cleanroom Renovation Ideas (1)
Changed from open ballroom to multiple narrower rooms to improve
airstream parallelism.
Used exhaust canopies to remove high-concentration particles generated
from process equipment. Room ACH reduced from 385 to 280.
Before After
Retrofits
Changed from general-purpose chemical lab to ISO Class-3 Nano research
lab in various aspects: Airflow rate, 100% HEPA ceiling with FFUs, tear-
drop lighting, and raised floor, etc.
Before After
Retrofits
Selective Cleanroom Renovation Ideas (2)
ISO-4 cleanroom (358 ACH) converted to ISO-3 cleanroom (400 ACH) with
lighting-integrated ceiling (yellow light area after filtered spectrum).
Replaced “primary-alone” AHU with “primary-secondary” AHU systems,
reduced energy consumption about 65%.
Before After
Retrofits
Selective Cleanroom Renovation Ideas (3)
Retrofitted a 22-ft height shop/storage area into a high-bay ISO-3 cleanroom
for aerodynamic research.
The cleanroom (280 ACH) has 2-ft wide return air chases on both sides, and
3-ft raised floor.
Before After
Retrofits
Selective Cleanroom Renovation Ideas (4)