This document provides an overview of a Trane seminar on clean room fundamentals. It discusses key clean room terminology, contamination sources, standards and classes, and design considerations. The seminar covers topics such as clean room history, particle concentration limits defined by standards, example clean room psychrometrics and calculations for sizing HVAC systems for a Class 10,000 clean room. The objective is to discuss fundamental design concepts for clean rooms.

1. Clean Room
Fundamentals
A Trane Seminar
© American Standard Inc. 2001
Seminar SYS_P19.PPT

2. Clean Room Fundamentals
1. Introduction
2. Terminology
3. Contamination sources
4. Standards and classes
5. Design considerations
6. Application considerations
7. Testing
8. Closing thoughts
© American Standard Inc. 2001
Objective: This Trane seminar
discusses the fundamental design
concepts used in clean rooms.
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3. Clean Room
Fundamentals
Section 1
Introduction
© American Standard Inc. 2001
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4. Introduction
Clean Room Technology
Started some 40 years ago
As the manufacturing technology advances,
more clean spaces are needed
Significant number of clean rooms are
microelectronics related
Pharmaceutical clean rooms control particles
and viable particles (mostly bacteria growth)
HVAC challenge is to be low cost
© American Standard Inc. 2001
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5. Introduction
The Facts
Microscopic fabrication, foods, automotive
paint, medical, aerospace, biological, and
other applications require clean and/or germfree atmospheres
Contamination affects health, laboratories,
hospitals, and selected manufacturing
processes
The best place to control particulates is at the
point of generation
© American Standard Inc. 2001
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6. Clean Room
Fundamentals
Section 2
Terminology
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7. Terminology
Use Established Terminology
Maintain a common language among everyone
in the project
Very important in written documents
Mission
Objective
Goal
Specs
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8. Terminology (partial list)
Aseptic space
Clean room
Clean space
Contamination
Critical parameter
Design conditions
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9. Terminology (continued)
High-efficiency particulate air filter (HEPA)
a filter with an efficiency in excess of 99.97% of 0.3 micron particles
Makeup air
Qualification & Qualification protocol
ULPA (ultra low penetration air) filter
Unidirectional flow
Validation
Workstation
© American Standard Inc. 2001
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10. Clean Room
Fundamentals
Section 3
Contamination
Sources
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11. Contamination Sources
Categories
External sources
Outdoor air (makeup air)
Adjacent spaces (doors, windows, cracks)
Internal sources
Personnel (one of most common sources)
Type of activity
Manufacturing process equipment
Products/material
Cleaning agents
Processes
Cross contamination
© American Standard Inc. 2001
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12. Contamination Sources
Examples
External source — urban areas
Typically contains 10 million particles (> 0.3 micron)
per cubic foot
Internal source — people
A seated or resting person releases 100,000 particles
(> 0.3 micron) per minute
NOTE
Air pollution refers to particles released outside the building, while
contamination refers to inside the building.
© American Standard Inc. 2001
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13. Contamination Sources
Contaminant Classification
Particulate
Solid
Liquid
Non-particulate
Gaseous
Other: ions, radiation, vibration…
© American Standard Inc. 2001
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14. Contamination Sources
Elimination Is Complex
Thoroughly understand processes to
adequately plan
Each process has requirements which in turn
define the cleanliness class
Goal: to control the contamination source
© American Standard Inc. 2001
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15. Clean Room
Fundamentals
Section 4
Standards and
Classes
© American Standard Inc. 2001
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16. United States
Standards and Classes
1960 — first clean room concept
(nuclear fusing and firing systems — Sandia Nat. Lab., NM. USA)
Aviation: gyroscope assembly
Semiconductors: microchip processing
HEPA filters
1966 — first federal standard -> classes
Current version is Fed-Std-209E (1992)
ISO Standard 14644-1 is the international
standard for clean rooms
NOTE
Fed-Std-209E does not specify air flow velocity — the owner and designer
should do it!
© American Standard Inc. 2001
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17. Standards and Classes
Airborne Particle Concentration Limits
Fed-Std-209E 0.5 micron
3
Class
particles/ft
1
10
100
1000
10,000
100,000
1
10
100
1000
10,000
100,000
ISO
3
particles/m
35
353
3,530
35,300
353,000
3,530,000
0.5 micron
Class
particles/m3
1
2
3
4
5
6
7
8
9
4
35
352
3,520
35,200
352,000
3,520,000
35,200,000
Cn = N (0.5/D)2.2 where, Cn = concentration limits in particles/ ft3, N = FS 209 class, and D = particle diameter in micron
Cn = 10N (0.1/D)2.08 where, Cn = concentration limits in particles/ m3, N = ISO class, and D = particle diameter in micron
SOURCE: ASHRAE 1999
NOTE
The concentration limits indicate the maximum number of particulates allowed
for a cleanliness class.
© American Standard Inc. 2001
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18. Standards and Classes
Air Cleanliness Class Limits
Particles per Cubic
Foot
100,000
Class
100,000
10,000
10,000
1,000
1,000
100
100
10
10
1
1
0
0.1
0.2
0.5
1
2
5
10
Particle Size
Source: FED-STD-209E
NOTE
The smaller is the class number and the highest is the cleanliness level.
© American Standard Inc. 2001
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19. Standards and Classes
Comparison of Parameters
Cleanliness
Class
Number of
Particles/ft3
Fed-Std-209E
d = 0.5 micron
1
10
100
1,000
10,000
100,000
Office 4
Filter
Coverage
1
1
10
100
1,000
10,000
100,000
(2 – 4 )× 106
Average Air
Velocity
Air
Changes
in percentages
fpm 2
per hour 3
> 90
> 90
> 85
30 – 60
10 – 20
5 – 10
—
60 – 90
50 – 90
40 – 80
25 – 40
10 – 15
1– 8
—
1 Comparisons:
360 – 540
300 – 540
240 – 480
150 – 240
60 – 90
5 – 48
3–6
human hair: d = 60 – 80 microns
red blood cells: d = 8 microns
2 Relative to total ceiling area
3 Room height = 3 meters (9.84 feet)
4 Consensus practice.
© American Standard Inc. 2001
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(5) 1 m/s = 196.85 fpm
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20. Clean Room
Fundamentals
Section 5
Design
Considerations
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21. Design Considerations
Criteria
Control the particles within a specified limit
The manufacturing process within the space
(room’s process) determines the cleanliness
classification
Design of clean room, should meet specific
requirements (the use and objectives) of the
project
© American Standard Inc. 2001
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22. Design Considerations
Thermal Load, Air Volumes
Estimate thermal cooling/heating load like
other spaces, but consider the room’s
manufacturing process
Set air volumes by:
Class of cleanliness (refer to Fed-Std-209E)
Air pattern
Clean room activity level
NOTES
When return air flows through perforated floor, the room’s shape matters.
The greater the class type, the greater the air volumes.
© American Standard Inc. 2001
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23. Design Considerations
Examples of Clean Room Shapes
Plan View
Elevation View
10 m
V = 0, 45 m/s
10 m
0.75 m
V = 6 m/s
V = 0, 45 m/s
20 m
0.375 m
V = 6 m/s
5m
© American Standard Inc. 2001
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24. Design Considerations
Example of Single Path Unit
RA
SA
OA
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25. Design Considerations
Single Path Psychometrics
OA
93° DB
F
75° WB
F
ROOM (R)
72°
F
50% RH
SA
58.8° DB
F
54.8° WB
F
M
76.6° DB
F
63.8° WB
F
F
LEAVING COIL (L) 54° DB
53.8° WB
F
OA
0.98
M
L SA
© American Standard Inc. 2001
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26. Design Considerations
Example of Dual Path Unit
Stacked
Dehumidification Unit
(SDU)
OA
Outside
(Primary)
Air
RA
SA
M
Return
(Secondary)
Air
© American Standard Inc. 2001
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27. Design Considerations
Dual Path Psychometrics
OA
93° DB
F
75° WB
F
ROOM (R)
72°
F
50% RH
SA
58.8° DB
F
54.8° WB
F
MIXTURE (M)
68° DB
F
58.7° WB
F
25.4 Btu/lb
LEAVING COIL (L)
54° DB
F
53.8° WB
F
OA
0.98
MR
L SA
© American Standard Inc. 2001
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28. Design Considerations
Example: Class 10,000
example room:
floor area = 2,545.5 ft2, ceiling height = 10 ft, room volume = 25,455 ft3
outdoor air = 93° dry bulb, 75° wet bulb, 38.3 Btu/lb, sea level elevation
F
F
space set points = 72° ± 0.5°dry bulb, 50% ± 5% relative humidity
F
assumptions:
supply air temperature = 54° DB (specific volume = 13.7 ft3/lb)
F
space sensible load = 234,600 Btu/hr
space sensible heat ratio (SHR) = 0.98
© American Standard Inc. 2001
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29. Design Considerations
Example: Calculation Summary
Q = m × cp × ∆ T
m = 234,600 / [0.24 × (72 - 54)] = 54,300 lb/hr
supply airflow = 54,300 × 13.7 ft3/lb = 743,986 ft3/hr or 12,400 cfm
air changes/hr (ach) = 746,986 ft3/hr / 25,455 ft3 = 29.2 ach
process requires 40 ach, so new supply airflow is:
40 ach x 25,455 ft3 = 1,018,200 ft3/h3 = 17,000 cfm = 74,321 lb/hr
outdoor air (OA) required for leakage (cracks/passages):
m′ = 2,627 cfm (cracks) + 1,120 cfm (passages) = 3,777 cfm = 16,542 lb/hr
© American Standard Inc. 2001
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30. Design Considerations
Example: Results
conventional single-path system:
cooling coil load, QC = m ×∆h = 74,321 × 7.5 / 12,000= 46.4 tons
reheat load, QRH = m ×cp × ∆T = 74,321 × 0.24 × 4.4 / 3,420 = 25 kW (7.1 tons)
single-path system: 46.4 + 7.1 = 53.5 tons (equivalent)
alternative dual-path system (precondition outdoor air):
separate coil preconditions outdoor air, OA′ (L) = 54° DB, 95% RH, 21.7 Btu/lb
F
OA cooling coil load, QOA = m ×∆h = 16,542 × (38.3 - 21.7) / 12,000 = 22.8 tons
mixture of OA′ and R, M = 68° DB, 58.7° WB, 25.4 Btu/lb
F
F
supply air condition for 40 ach, SA = 58.8° DB, 54.8° WB, 23 Btu/lb
F
F
cooling coil load to cool mixed air from M to SA,
QM = m ×∆h = 74,321 × (25.4 - 23) / 12,000 = 14.8 tons
dual-path system: 22.8 + 14.8 = 37.6 tons
© American Standard Inc. 2001
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31. Design Considerations
Temperature Control
Provide stable conditions for instruments,
materials and comfort
Range
Control a constant temperature
Accuracy (tolerances: ~1° or 0.1 – 0.5°
F;
F)
Comfort conditions
Use independent humidity and temperature
controls
© American Standard Inc. 2001
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32. Design Considerations
Humidity Control
The room’s process determines the required
humidity and tolerance *
Humidity control is necessary to…
Prevent condensation and corrosion
Eliminate static electricity
Maintain comfort conditions
RH range should stay between 30 - 50% with
tolerances of ~ 0.5 to 5%
NOTE
Use independent humidity and temperature control.
© American Standard Inc. 2001
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33. Design Considerations
Makeup and Exhaust Air
Makeup air (MA)
Affects pressurization, humidity, and cleanliness
Volume is a function of process exhaust &
pressurization
Pre-filtered based on contamination level and relative
position to main HEPA filters
Process exhaust air
Process exhaust depends on the room’s process
Exhaust air should be treated before it’s delivered to
the atmosphere
© American Standard Inc. 2001
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34. Design Considerations
Pressure
Pressurization
Causes air to migrate to least clean area
Differential pressure 0.05 in. wg (~0.01 to ~0.03 in. wg)
Should be kept as low as possible
Pressure level results from the balance of…
Process exhaust
Makeup air
Leakage
Supply and return air volumes
© American Standard Inc. 2001
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35. Design Considerations
Pressurization Illustration
Airlock with
interlocked doors
(++)
Product out
Gown
(++)
Aseptic Core
Degown
Class 10,000
(++)
Aseptic Fill
(+++)
(+++)
Autoclave
Mech
space
Autoclave
Mech
space
Oven
Formula preparation
Class 100,000
Autoclave
Glass wash
(++)
Class 100,000
(++)
(+)
(+)
Material
(+)
Personnel
(+)
Room pressurization level
above zero reference
Unidirectional airflow
(curtained area optional)
Equipment
SOURCE: ASHRAE 1999
© American Standard Inc. 2001
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36. Design Considerations
Filtration and Type of Air Cleaners
Filtration helps to prevent contamination
Fibrous media unit
Viscous impingement filters
Dry-type extended-surface filters, low- and highefficiency air filters (the last)
High-efficiency particulate air (HEPA)
Ultra-low penetration air (ULPA)
Renewable media filters
Electronic air cleaners
Combination air cleaners
© American Standard Inc. 2001
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37. Design Considerations
Filters
Prefilter
Prefilter/Filter
Consider need for
filtration of exhaust air
Final filter
Return air
?
Outside air
H&C coils,
washers, etc.
Moisture eliminator
(if required)
Steam
humidifier
Space
Exhaust fan
SOURCE: ASHRAE 2000
© American Standard Inc. 2001
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38. Design Considerations
“Ballroom” with Fan Filter Units
Plan View
Elevation View
Air handler
FFUs
Make-up
air supply
to plenum
Advantage: Easy to
change cleanliness class.
Visitors
corridor
© American Standard Inc. 2001
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39. Design Considerations
“Comb” with Fan Filter Units
Equipment through partition
Products
entry/exit
Clean area
Support/service area
Maintenance
corridor
Clean
corridor
Production area
Maintenance shop/spare parts
Dressing rooms
Clean
tools
Fan filter units with HEPA filters
Exhaust
Treated outside air
(make-up)
Service
© American Standard Inc. 2001
Return air
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40. Design Considerations
Air Pattern
Objective
Cleanest air at the critical areas conveyed to less
critical areas
Large flow at low velocity
Unidirectional movement (usually downward)
Air flow patterns
Unidirectional flow (“laminar”) — air evenly distributed
from one entire surface of the room (ceiling or wall)
at constant velocity
Single direction, single pass, parallel streamlines
© American Standard Inc. 2001
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41. Design Considerations
Unidirectional Air Pattern
(classes 1000, 100, 10, 1)
Vertical
Total displacement with ceiling HEPA or ULPA filters
(class 100 or better)
Down-flow with HEPA filters
Return or exhaust air perforated floor
(not recommended for pharmaceutical clean rooms)
Horizontal
Across a section of the room (wall-to-wall)
© American Standard Inc. 2001
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42. Design Considerations
Air Pattern Unidirectional Air Flow
(classes 1000, 100, 10)
HEPA-filtering
ceiling
The air volume of the entire room flows at an uniform velocity,
following parallel streamlines
This “displacement flow” provides a higher cleanliness class
© American Standard Inc. 2001
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43. Design Considerations
More Air Patterns
Non-unidirectional (classes 100,000,10,000 & 1,000)
Either non-parallel flow or multiple passes
Turbulent mixing (dilution) flow, high air change rates,
and ceiling partially covered with HEPA filters
Mixed configuration
Non-unidirectional area flow plus unidirectional
module (currently used on pharmaceutical industry)
© American Standard Inc. 2001
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44. Design Considerations
Air Patterns Illustration
Secondary
air handler
Primary
air handler
Outside
air
99.999%, HEPA or
ULPA filters in ceiling
Return air
Return air
Class 10,000
non-unidirectional airflow
Class 100
unidirectional airflow
SOURCE: ASHRAE 1999
© American Standard Inc. 2001
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45. Design Considerations
Air Patterns Illustration
Air handler
Outside
air
In-line HEPA or ULPA filter
Return air
Return air
Class 100
localized airflow
© American Standard Inc. 2001
Class 10,000
non-unidirectional airflow
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SOURCE: ASHRAE 1999
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46. Design Considerations
Optimize Cleanliness Class
Restrict to class 1, 10, 100 unidirectional
airflow where the product is exposed
Install partitions to shield “laminar flow” area
Use class 10,000 or 100,000 turbulent mixing
flow for adjacent areas
The result will be a reduction of
installation and operating costs!
© American Standard Inc. 2001
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47. Design Considerations
Noise and Vibration
Establish noise and vibration criteria
Noise is produced by process equipment and the HVAC
system
Vibration is a contaminant in microelectronic plants
Process equipment senses low-frequency vibration (more difficult
to attenuate)
Sources: rotating machines, fluids in piping, air flowing in duct
system
Use vane-axial fans (high rpm) instead centrifugal
(low rpm)
Avoid reciprocating compressors (air or refrigeration)
© American Standard Inc. 2001
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48. Design Considerations
Energy Savings
Controlling a clean room requires high energy
Treating the makeup air
Air movement
Process exhaust
Do an energy analysis
Fans
Makeup and exhaust air
© American Standard Inc. 2001
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49. Design Considerations
Air Conditioning Systems
Future process/equipment changes
Microelectronic manufacturing functions
Flexibility
Proper sizing
Redundancy
Process exhaust fans
Life-cycle economic analysis
Energy conservation
© American Standard Inc. 2001
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50. Clean Room
Fundamentals
Section 6
Application
Considerations
© American Standard Inc. 2001
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51. Applications
Microelectronic Plants
Require class 100 or better due to the size of
their product, circuits
Goal is less than 1 particle 0.1 micron and larger per
ft3 of air
Usual design types
Clean tunnel
Open bay
© American Standard Inc. 2001
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52. Applications — Microelectronic Plants
Clean Tunnel Design
Modular (~ 8ft to 14ft wide)
HEPA, ULPA filters, or fan-filter modules
Advantage
Reduced filter coverage
Disadvantages
Restricts new equipment layouts
Restricts moving products between equipment
© American Standard Inc. 2001
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53. Applications — Microelectronic Plants
Clean Tunnel Design
Air duct connections
HEPA or ULPA filter
modules in ceiling grid
Work area
Tunnel
wall
Product
SOURCE: ASHRAE 1999
© American Standard Inc. 2001
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54. Applications — Microelectronic Plants
Open Bay Design
(up to 100,000 ft2)
Pressurized plenum or ducted filter modules
30,000 ft2 or larger sometimes combine tunnel
and open bay
Advantage
Flexibility (equipment layout changes)
Disadvantage
Larger filtration coverage
© American Standard Inc. 2001
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55. Applications — Microelectronic Plants
Air Flow
Fed-Std-209E classes 100,10, and 1
Vertical, unidirectional airflow
(w/ HEPA or ULPA filters)
Pressurize plenum above filters (even pressure
may be a problem)
Individual ducted filters (higher static loss, higher
maintenance cost due to balancing the system)
Individual fan-filter units (FFU)
Return through-the-floor is recommended
© American Standard Inc. 2001
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56. Applications
Pharmaceutical Plants
Distinct from other clean spaces
Design must consider…
Room finishes
Room operations
Process equipment
HVAC
Controls
Utilities
All people related to the facility should be
involved in the design phase
They define the cleanliness class (and necessary
barrier technology or isolators)
NOTE
Owner and designer must define the QP as well as drawings, specifications,
critical components, maintenance files, and training.
© American Standard Inc. 2001
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57. Applications — Pharmaceutical Plants
Qualification Plan (QP)
Functional requirement specifications (FRS)
Critical parameters & acceptance criteria
Qualification procedure protocols (QPP)
Installation qualification (IQ)
Operational qualification (OQ)
Performance qualification (PQ)
All should be
considered during
the design process.
Standard operating procedures (SOPs)
Preventive maintenance (PM)
Operator & maintenance personnel training
Approval procedure
© American Standard Inc. 2001
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58. Applications — Pharmaceutical Plants
Documents
In the USA, FDA inspection is required
Documents that must be considered
Code of Federal Regulations 210 and 211
International Society for Pharmaceutical Engineering
(ISPE) Guides
National Fire Protection Association (NFPA Std)
Publications from the Institute of Environmental
Sciences and Technology (IEST)
Protocols
NOTE
FDA stands for Food and Drug Administration.
© American Standard Inc. 2001
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59. Applications — Pharmaceutical Plants
Good Manufacturing Practice (GMP)
Proper and repeatable method of producing
sterile products — free from particle and
microbial contaminants
GMP documents should include test reports
for HEPA filters at operating air velocities
Efficiency
Pinhole integrity
Europe
Pharmaceutical industry adopted the European Union
Guide to GMP for Medicinal Products in 1992
© American Standard Inc. 2001
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60. Clean Room
Fundamentals
Section 7
Testing
© American Standard Inc. 2001
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61. Testing
Fundamental Tests
Cleanliness class
Air movement
Room (or zones) conditions
NOTE
IEST describes 12 tests for clean rooms.
© American Standard Inc. 2001
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62. Testing
Validation Tests
Tests depend on clean room type
Unidirectional flow
Non-unidirectional flow
Mixed flow
Three distinct steps to complete
Clean room as-built
Clean room at-rest
Operational clean room
© American Standard Inc. 2001
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63. Clean Room
Fundamentals
Section 8
Closing Thoughts
© American Standard Inc. 2001
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64. Closing Thoughts
A Successful Clean Room
Commitment
Teamwork (owner, architect, consultant,
contractor)
Defined responsibility
Judicious design, simplicity
Procedures
Coordination
Testing
Documentation
© American Standard Inc. 2001
The team members should work
together for a successful, complete
product — a building that all can
be proud of.
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65. Clean Room Fundamentals
References
ASHRAE
1981 Symposium: CI-81-5 No.: 3/4 (709-717)
1986 Transactions No.: SF-86-06 (pages 272-84)
1987 Symposium: NY-87-13-1 (1279-1287)
1990 Symposium No.: SL-90-5-1/2/3/4 (609-633)
1994 Transactions No.: NO-94-18-1/2 (1257-1374)
1994 Transactions No.: NO-94-28-1/2/3/4 (1629-1651)
1994 Transactions No.: NO-94-29-1/2 (1655-1675)
1997 Applications Handbook
Federal Standard: Fed-Std-209E (September 1992)
IEST Publications
Sulzer, Switzerland: Clean Spaces Techniques & Applications
Brazilian Society of Contamination Control: 1994 Seminar
© American Standard Inc. 2001
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