Hazardous Gas Monitoring. A Guide for Semiconductor and Other Hazardous Occupancies

208 Pages·2000·2.51 MB·English

by  Logan T. White (Auth.)

FIGURES
.1 Simplified PLC-based gas monitoring system. 128
2. Simplified fire alarm panel-based gas monitoring system. 132
3. Simplified proprietary network-based gas monitoring system. 134
4. Simplified LonWorks network-based gas monitoring system. 136
5. Typical alarm system matrix. 144
6. Factory Mutual system certification chart. 154
TABLES
Safety Integrity Level (SIL) Standards & Classes 66
Hazardous Gases Typically Monitored ni Semiconductor Facilities 163
1995 Supplement to CFU Table A-VI-A-1 -- Normalization Factor 177
ix
FIGURES
.1 Simplified PLC-based gas monitoring system. 128
2. Simplified fire alarm panel-based gas monitoring system. 132
3. Simplified proprietary network-based gas monitoring system. 134
4. Simplified LonWorks network-based gas monitoring system. 136
5. Typical alarm system matrix. 144
6. Factory Mutual system certification chart. 154
TABLES
Safety Integrity Level (SIL) Standards & Classes 66
Hazardous Gases Typically Monitored ni Semiconductor Facilities 163
1995 Supplement to CFU Table A-VI-A-1 -- Normalization Factor 177
ix
CAVEAT
Purpose.
This guide is intended to provide an overview of the subjects
contained herein, and is intended to be used solely for general information only.
Misapplication/Misunderstanding.
The author cannot assume
any liability with regard to the misinterpretation or misapplication of any code
provision, monitoring system, or life-safety alarm which may result from the
use of this guide.
User Responsibility.
The user is solely responsible for researching
current codes and systems and application of the principles and requirements
of the codes and other regulations and monitoring systems or alarms to each
specific set of circumstances.
Code Compliance.
Codes and standards regulating hazardous gas
monitoring are continuously revised and enacted and it is the user's
responsibility to research the most current applicable regulations. Compliance
plans should be discussed with, and have the approval of, the local Authorities
Having Jurisdiction.
Changing Technology.
Hazardous gas monitoring technology is a
rapidly changing field which demands that those using or designing monitoring
systems assume responsibility for keeping abreast of the latest developments.
The information in this guide is accurate to the best of our knowledge at the
time of publication; however, the author does not assume any responsibility or
liability for the accuracy or completeness of, or consequences arising from,
such information.
Commercial .stcudorP
Reference in this guide to commercial products
does not constitute endorsement or recommendation for use by the author. It
is the sole responsibility of the user to make final determination of the
suitability of any information or product and the manner of that use. Anyone
intending to rely upon any recommendation of materials or procedures
mentioned in this guide should satisfy himself as to such suitabililty and further
determine that all applicable safety and health standards are met.
ACKNOWLEDGMENTS
Grateful acknowledgment is made to the following people for
their comments and input during the creation of this guide...
Reinhard Hanselka of Advanced Industrial Designs
for his critical review comments...
Kelly Erin O'Brien of Envirodata for her University of
California Santa Cruz course which inspired this guide . . .
Dean Novy of SDN Technology, Fremont, California,
for his insight into design firm considerations...
Jim Hills for sharing his wealth of experience...
and CH2M Hill Industrial Design Corporation
of Portland, Oregon.
Thanks go to the many industry professionals who provided
valuable information ...
Ken Eichelmann of Scott/Bacharach...
PhilA lderman and Steve Pitts of MST . . .
Don Bell of Edwards Systems Technologies...
Thorn Walczak and Bill Madison of EG Fanuc...
Ekkehard Pofahl of TUV Rheinland . ..
Lou Chavez of Underwriters Laboratories...
Richard Witte of Metron Technology...
AI Carrino of PureAire...
Kevin Williams and Les Wulf of Zellweger Analytics...
Gordon Simpkinson of the Palo Alto Fire Department...
and Paris Stavrianidis of Factory Mutual.
I also thank the many colleagues and friends who offered advice
and encouragement.
xi
ACRONYMS / ABBREVIATIONS
(see Glossary for additional acronyms)
AHJ Authority Having Jurisdiction
SCE Emergency Control Station
EP/E/E Electrical/Electronic/Programmable Electronic
EMCS Energy Management Control System
TRE Emergency Team Response
CVE Equilibrium Vapor Concentration
MF Factory Mutual
RITF Fourier Transform Infrared
HPM Hazardous Production Material
HLDI Immediately Dangerous to Life & Health
CFI International Fire Code
IPA Isopropyl Alcohol
RI Infrared
ISA International Society of Measurement and Control
o~CL 50 Percent Lethal Concentration Level
LDL Lower Detection Limit
LEL Lower Explosive Limit
LFL Lower Flammable Limit
COL Level of Concern
Max TQ Maximum Threshold Quantity
Mg/Kg Milligrams rep Kilogram
MHI Material Hazard Index
MSDS Material Safety Data Sheet
CEN National Electric Code
NFPA National Fire Protection Association
NIOSH National Institute of Occupational Safety and Health
LEO Occupational Exposure Limit
OTV Odor Threshold Value
LEP Permissible Exposure Limit
CLP Programmable Logic Controller
BPP Part per Billion
MPP Part per Million (equivalent to Mg/Kg)
IFR Radio Frequency Interference
SlL Safety Integrity Level
SIS Safety Instrumented System
CLS Safety Life Cycle
SRS Safety Related Systems
LETS Short-term Exposure Limit
TGO Toxic saG Ordinance
TLV Threshold Limit Value
TWA Time Weighted Average
CBU Uniform Building Code
CFU Uniform Fire Code
LFU Upper Flammable Limit
LU Underwriters Laboratories
VMB Valve Manifold Box
xii
Hazardous saG Monitoring
(cid:12)9
Codes require that air in areas that use, handle or store hazardous production materials
be monitored for dangerous concentrations of these gases. Hazardous production
materials (HPMs) include substances that are toxic, highly toxic, flammable,
combustible, pyrophoric, reactive, corrosive or oxidizing, as well as some cryogenic
and refrigeration gases.
Because many of the gases used in industry have very poor physiological warning
properties (odor thresholds) relative to their dangerous concentrations, monitoring
systems are necessary. In addition to monitoring gas releases, codes also include
requirements for containment and management of hazardous materials. These
containment systems must eb monitored for leaks to ensure that they are functioning
properly.
The need for monitoring is illustrated by the extreme toxicity of some gases to which
short-term exposure of minute amounts (from ppb to ppm) can cause serious adverse
effects including death. As an example of toxicity, arsine (ASH3) is used in
semiconductor manufacture as a dopant. Arsine's permissible exposure limit (PEL) is
50 parts per billion--200 times lower than the LEP for hydrogen cyanide, the lethal
agent commonly used for executions. The ACGIH proposes lowering the TLV for
arsine to 2 ppb. Many cleanroom ion implanters contain lecture bottles that hold 40
to 50 liters of arsine. A leak of as little as two cubic feet of 100 percent arsine gas
could fill a 10-foot-high, 28-foot-square room (7,840 cubic feet) with a lethal
concentration (250 ppm) of this gas.
While toxic and flammable gases receive the most attention, inert gases can also pose
a danger. Some gases can displace ambient oxygen to the extent that the area
becomes hazardous for personnel. Gas detection systems can generate alarms if the
oxygen concentration drops below 1 9.5 percent. Semiconductor fabrication facilities
generally contain a dedicated storage room for inert gases. Some authorities having
jurisdiction require monitoring for oxygen depletion in these inert gas storage rooms.
2 SUODRAZAH SAG GNIROTINOM
The Uniform Building Code (UBC) and the Uniform Fire Code (UFC) are nationally-
recognized model codes that address hazardous gas monitoring to a certain extent and
are adopted by many local jurisdictions. However, there is usually significant lag time
between the use of new hazardous production materials and the development of codes
specific to their regulation. Some jurisdictions modify the model codes by providing
amendments addressing specific concerns of the authority having jurisdiction (AHJ).
As a result, many local jurisdictions have developed codes that conflict with, or expand
upon, model codes. The first step in developing a facility hazardous gas monitoring
and alarm system is to determine from the local authority having jurisdiction which
codes they have adopted including any modifications.
Codes relating to hazardous gases are more developed in the San Francisco Bay Area
(Silicon Valley) due to the concentration of semiconductor manufacturing facilities in
the region. As an example, the Santa Clara County Fire Chiefs Association developed
their own model toxic gas ordinance (TGO) as a guide for the cities in that county.
Although many of the Bay Area municipalities did adopt Santa Clara County's model
code, some cities have enacted codes that differ from Santa Clara County's TGO.
The purpose of this guide is to give designers, facility owners and operators, suppliers
and code officials an overview of the various code requirements and recommended
applications that apply to the design and operation of hazardous gas monitoring and
alarm systems.
Manufacturing processes and the codes that regulate them are constantly evolving.
As safety considerations are identified, code provisions are developed by industry and
regulatory authorities. According to Reinhard Hanselka, a respected leading authority
on semiconductor industry codes, "the semiconductor industry uses the highest
standard of care of any industry anywhere in the world." The rapid development of
relevant codes is the result of the young semiconductor industry pursuing a higher
standard of care than long-established industries.
Codes are not intended to eb used as design specifications or instructional manuals,
and are constantly evolving. Excerpts from various codes in the following text are for
the reader's convenience and are not a substitute for research into the full body of
currently-enacted applicable codes.
Best Industry Practice & Code Intent
This guide includes excerpts from several codes regarding the use and monitoring of
hazardous materials. Regulatory agencies develop codes to safeguard the public and
property from recognized hazards. Most codes emphasize that their requirements are
intended to eb minimum standards. roF example, the National Electrical Code states:
HAZARDOUS GAS GNIROTINOM 3
This Code contains provisions considered necessary for safety. Compliance
therewith and proper maintenance will result in an installation essentially free
from hazard, but not necessarily efficient, convenient, or adequate for good
service or future expansion of electrical use .... This Code is not intended as
a design specification nor an instruction manual for untrained personnel
This Code prescribes regulations consistent with nationally recognized practice
for the safeguarding to a reasonable degree of life and property from the
hazards of fire, explosion, and dangerous conditions arising from the storage,
handling and use of hazardous materials and devices, and from conditions
hazardous to life or property in the use or occupancy of buildings or premises
and provisions to assist emergency responsepersonneL
Codes allow the use of alternate methods and materials provided that the spirit of the
code is met. Refer to the discussion of Alternate Materials and Methods in Chapter
6 of this guide.
Codes are developed by committee, follow technology, may not be immediately
adopted by local jurisdictions, may be locally amended, and do not necessarily require
the use of the best industry practice. The real-world standard to which one would be
held in a court of law is the opinion of your peers called to testify as expert witnesses
for or against you.
Codes are considered minimum requirements and do not necessarily provide a good
design. It may be indefensible to ignore additional life-safety features in a system
simply because they are not required by the authority having jurisdiction. The best
industry practice is to incorporate all of the design features that will enhance life safety
and minimize hazards to environment and property.
Prescriptive versus Performance. Standards and codes are moving away from
prescriptive requirements to eb more performance-oriented. Earler codes directed the
use of a specific method to achieve a result. Newer codes mandate a performance
while not prescribing a specific means to achieve the result. While prescriptive
rquirements may be easier to understand and to implement, performance-oriented
requirements allow the use of new technologies and methods to meet an intent.
Occupancy Classifications
A first step in researching code requirements is to determine the occupancy
classification of every area within the facility. In the 1997 Uniform Fire Code and
Uniform Building Code, semiconductor fabrication facilities were Uniform Building
Code Group H, Division 6 classification.
4 HAZARDOUS GAS MONITORING
1997 UBC 307.1.1 General Group H occupancies shaft include buildings or
structures, or portions thereof that involve the manufacturing, processing,
generation or storage of materials that constitute a high fire, explosion, or
health hazard...
Division 6. Semiconductor fabrication facilities and comparable research and
development areas in which hazardous production materials (HPM) are used and
the aggregate quantity of materials are in excess of those listed in Table 3-D or
3-E. Such facilities and areas shaft be designated and constructed in
accordance with section 411.
Occupancy classifications in other jurisdictions, such as the Standard Building Code,
may differ. In addition to CBU H-6 classifications, UBC Group H, Division 3 and
Division 7 may apply to storage of hazardous materials at semiconductor fabrication
facilities.
The 2000 International Fire Code revised occupancy classifications for hazardous
Group H. Group 1-H now covers buildings and structures which contain materials that
pose a detonation hazard and includes detonable pyrophoric materials. Group H-2
covers buildings and structures which contain materials that pose a deflagration hazard
or a hazard from accelerated burning and includes flammable and pyrophoric gases.
Group H-3 covers buildings and structures which contain materials that readily support
combustion or pose a physical hazard and includes oxidizing gases. Group H-4 covers
buildings and structures which contain materials that are health hazards and includes
corrosives, highly toxic and toxic materials. Group H-5 covers semiconductor
fabrication facilities and comparable research and development areas in which
hazardous production materials are used and the aggregate quantity of materials is in
excess of those listed in CFI tables 307.7(1) and 307.7(2).
In previous editions of codes, semiconductor fabrication facilities were classified as
Group H-6, storage of pyrophoric and flammable gases was Group H-2, and toxic and
highly toxic storage was Group H-7.
Research Laboratory Facilities. Recent toxic gas ordinances in the Bay Area have
addressed the problem of research laboratories falling under the same requirements
as large semiconductor manufacturing facilities. Some jurisdictions now allow
laboratories to meet less stringent requirements based on material quantities. The Palo
Alto, California, TGO provides a section on minimum threshold quantity controls which
would apply to laboratories.
HAZARDOUS SAG GNIROTINOM 5
Alterations to Existing Facilities
It may be necessary to meet current code requirements when repairing, retrofitting,
renovating, or adding to an existing semiconductor manufacturing facility. Although
the original facility met the requirements of an earlier code in force at the time of
construction, additions or alterations must comply with current codes. Alterations or
additions may trigger the requirement for upgrades to existing safety systems.
Early in the schematic design phase, compliance should be discussed with the code
officials to determine the extent of required upgrades to the existing facility.
Risk Management & Corporate Safety Standards
Corporate risk management often specifies design standards which exceed the
minimum code requirements. It is advisable to coordinate with the facility loss
prevention or risk management team and insurance carrier early in design. Many
semiconductor manufacturers define their own safety standards, which must be
incorporated into their hazardous gas monitoring systems.