ASHRAE Journal - November 2020 - 56
COLUMN ENGINEER'S NOTEBOOK
FIGURE 1 The epitaxial (EPI) cleanroom system. See Figure 1 Notes on facing page for details.
OA Isolation
Damper
Integral Face and Bypass
Type Steam Preheat Coil
LPS
30% Prefilters LPR
Chilled Water
Steam
Cooling Coil Reheat Coil
LPS
CWS
Chemical and
95% Final Filters
HEPA Filters
LPS
LPR
CWR
Smoke Exhaust Fan
Humidifier
1
Redundant Supply Fans
With Backdraft Dampers
Smoke Exhaust
Makeup Air
Backdraft Damper
(Typical)
Makeup AHU
Attenuator
4
Recirculation
Fan
Equipment 8
Room
Clean
Corridor
Recirculation
AHU
Attenuator
Smoke Control
Cycle Damper Supply
(Typical) Plenum
Reheat Coil
Acid Etch
And QC
Room
7
EPI Cleanroom
(aka "The Fab")
6
Production Tool
Subfloor/Return Plenum
Redundant
Process
Exhaust Fans
With Backdraft
Dampers
2
Plenum Divider 5
Reheat Coil To Other
Zones
8
Clean
Corridor
Equipment
Room
Recirculation
AHU
3
Scrubber
4
Attenuator
4
pulled negative, This reversed the flow through all the
door cracks and other leakage paths and contaminated
the entire cleanroom in addition to the QC area. But it
did provide enough flow to allow the process exhaust fan
to achieve near design flow.
Bottom-line, the N + 1 MAU and process exhaust fans
did not protect the fab from going out of production in
this failure mode because the failure was not associated
with the fans; it was with the systems that controlled the
fans.
N + 1 and Fab Crashes
ASHRAE JOURNAL
PHOTO 1 The fab under construction.
The EPI Cleanroom
As I settled into my new position, a bigger problem
emerged. The cleanroom was running under a temporary certificate of occupancy, allowing us to begin
qualification work while the final details of the fab construction were worked out. This included demonstrating
the response of the cleanroom to various failure modes,
including the failure of a process exhaust fan.
Since the owner's personnel believed the contract was
for a system in which the failure of a process exhaust fan
would not take the cleanroom out of production, once
56
the various safety devices were verified (hazardous gas
alarms, flow switches, etc.), they saw no reason to not
work in the fab while testing was going on.
The design build contractor's approach to operating
the N + 1 process exhaust fans was: If the fan that was online
failed, start the lag fan.
ashrae.org
N OVEM BER 2020
https://www.ashrae.org/
ASHRAE Journal - November 2020
Table of Contents for the Digital Edition of ASHRAE Journal - November 2020
Contents
ASHRAE Journal - November 2020 - Intro
ASHRAE Journal - November 2020 - Cover1
ASHRAE Journal - November 2020 - Cover2
ASHRAE Journal - November 2020 - 1
ASHRAE Journal - November 2020 - Contents
ASHRAE Journal - November 2020 - 3
ASHRAE Journal - November 2020 - 4
ASHRAE Journal - November 2020 - 5
ASHRAE Journal - November 2020 - 6
ASHRAE Journal - November 2020 - 7
ASHRAE Journal - November 2020 - 8
ASHRAE Journal - November 2020 - 9
ASHRAE Journal - November 2020 - 10
ASHRAE Journal - November 2020 - 11
ASHRAE Journal - November 2020 - 12
ASHRAE Journal - November 2020 - 13
ASHRAE Journal - November 2020 - 14
ASHRAE Journal - November 2020 - 15
ASHRAE Journal - November 2020 - 16
ASHRAE Journal - November 2020 - 17
ASHRAE Journal - November 2020 - 18
ASHRAE Journal - November 2020 - 19
ASHRAE Journal - November 2020 - 20
ASHRAE Journal - November 2020 - 21
ASHRAE Journal - November 2020 - 22
ASHRAE Journal - November 2020 - 23
ASHRAE Journal - November 2020 - 24
ASHRAE Journal - November 2020 - 25
ASHRAE Journal - November 2020 - 26
ASHRAE Journal - November 2020 - 27
ASHRAE Journal - November 2020 - 28
ASHRAE Journal - November 2020 - 29
ASHRAE Journal - November 2020 - 30
ASHRAE Journal - November 2020 - 31
ASHRAE Journal - November 2020 - 32
ASHRAE Journal - November 2020 - 33
ASHRAE Journal - November 2020 - 34
ASHRAE Journal - November 2020 - 35
ASHRAE Journal - November 2020 - 36
ASHRAE Journal - November 2020 - 37
ASHRAE Journal - November 2020 - 38
ASHRAE Journal - November 2020 - 39
ASHRAE Journal - November 2020 - 40
ASHRAE Journal - November 2020 - 41
ASHRAE Journal - November 2020 - 42
ASHRAE Journal - November 2020 - 43
ASHRAE Journal - November 2020 - 44
ASHRAE Journal - November 2020 - 45
ASHRAE Journal - November 2020 - 46
ASHRAE Journal - November 2020 - 47
ASHRAE Journal - November 2020 - 48
ASHRAE Journal - November 2020 - 49
ASHRAE Journal - November 2020 - 50
ASHRAE Journal - November 2020 - 51
ASHRAE Journal - November 2020 - 52
ASHRAE Journal - November 2020 - 53
ASHRAE Journal - November 2020 - 54
ASHRAE Journal - November 2020 - 55
ASHRAE Journal - November 2020 - 56
ASHRAE Journal - November 2020 - 57
ASHRAE Journal - November 2020 - 58
ASHRAE Journal - November 2020 - 59
ASHRAE Journal - November 2020 - 60
ASHRAE Journal - November 2020 - 61
ASHRAE Journal - November 2020 - 62
ASHRAE Journal - November 2020 - 63
ASHRAE Journal - November 2020 - 64
ASHRAE Journal - November 2020 - 65
ASHRAE Journal - November 2020 - 66
ASHRAE Journal - November 2020 - 67
ASHRAE Journal - November 2020 - 68
ASHRAE Journal - November 2020 - 69
ASHRAE Journal - November 2020 - 70
ASHRAE Journal - November 2020 - 71
ASHRAE Journal - November 2020 - 72
ASHRAE Journal - November 2020 - 73
ASHRAE Journal - November 2020 - 74
ASHRAE Journal - November 2020 - 75
ASHRAE Journal - November 2020 - 76
ASHRAE Journal - November 2020 - 77
ASHRAE Journal - November 2020 - 78
ASHRAE Journal - November 2020 - 79
ASHRAE Journal - November 2020 - 80
ASHRAE Journal - November 2020 - Cover3
ASHRAE Journal - November 2020 - Cover4
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_MCDEBX
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_WNYSQY
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_XATVOD
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_FJSHSS
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_CCBZDS
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_XDEFVG
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2023november_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2023november
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_VHGNBL
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_WPKBNJ
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_UUVCDE
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_RTGDEW
https://www.nxtbook.com/nxtbooks/ashrae/ashraemexico_2023
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_LKRFXS
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_AZSOFG
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_ERCDBH
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_QWDFRV
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_JHGVDF
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_OPUYHG
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_SREIBM
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_LRTGLK
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_OKRFGH
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2022november_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2022november
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_TZSERA
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_LVRUIX
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_RPTVYZ
https://www.nxtbook.com/nxtbooks/ashrae/mini_pub_catalog
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_XIYTGD
https://www.nxtbook.com/nxtbooks/ashrae/ashraemexico_2022
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_RFGDOB
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_PABXNU
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_REMKLS
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_PICVBT
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_AOYTVW
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_JQOPLS
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_IOYTBC
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_SGAJJF
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_IGHYER
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_PDRKLS
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2021november
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2021november_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_XCODFR
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_QSLFGO
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_ILKVNM
https://www.nxtbook.com/nxtbooks/ashrae/ashraemexico_2021
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_OPDJKD
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_VJKSRY
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_SDHUTC
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_JPPKRR
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_SDLTTH
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_CKLLES
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_SLDOX
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_HJETUK
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_OLUHGE
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2020october
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2020october_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_ZERDGH
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_QVMNEO
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_RTPOKE
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_BBATRE
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_STUBMW
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_TPEMPE
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_JNMKDS
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_FBTTPA
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_WQMMNE
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_TVBRYN
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_showguide2020
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_KTUZMA
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_ABEDGD
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201910
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201909
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2019septmeber_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2019september
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201908
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201907
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201906
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201905
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201904
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_2019april
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201903
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_2019march
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201902
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201901
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_showguide2019
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_2018december
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_2018november
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2018fall_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2018fall
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_2018october
https://www.nxtbook.com/nxtbooks/ashrae/ashraemexico_2018
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201810
https://www.nxtbook.com/nxtbooks/ashrae/ashraeinsights_201806
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201805
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201804
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201803
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201712
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201711
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201710
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2017fall_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2017fall
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201709
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201705
https://www.nxtbook.com/nxtbooks/ashrae/ashrae_meetinginsert_201610
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2016fall_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2016fall
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_acrexindia
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2015summer_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2015summer
https://www.nxtbook.com/nxtbooks/amca/2014summer2
https://www.nxtbook.com/nxtbooks/amca/2014summer
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_acma_2014summer
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201311
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201309
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_acmasupp_2013fall
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201305
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201303
https://www.nxtbook.com/nxtbooks/ashrae/pubcatalog_2013winter
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201211
https://www.nxtbook.com/nxtbooks/ashrae/achr_expo_mexico2012
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201209
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201208_v3
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201208_v2
https://www.nxtbook.com/nxtbooks/ashrae/pubcatalog_2012summer
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201205
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201203
https://www.nxtbook.com/nxtbooks/ashrae/pubcatalog_2012winter
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201111_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201109_v2
https://www.nxtbook.com/nxtbooks/ashrae/pubcatalog_2011summer
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201105
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201103
https://www.nxtbookmedia.com