semi合集-English.pdf - 第7068页
SEMI S18-1102 © SEMI 2002 6 8 Leak Detection and Alarm Sy stems 8.1 General 8.1.1 Audible and visual alarm s should be provided at a location where they can be seen and heard by workers. 8.1.2 Remote audible and visual a…
SEMI S18-1102 © SEMI 2002
5
6.5.3.3 The user should introduce silane family gases
only after purging oxidizing gases and other
incompatible gases, materials or substances from the
system.
6.5.3.4 Silane family gas systems should have
procedures based on calculated minimum purge cycles,
minimum purge-gas pressures, and necessary vacuum
levels to insure the system has been adequately purged
before being opened to atmosphere. Calculations are
needed to define minimum number of cycles. Process
purges typically far exceed this number of cycles,
therefore testing is usually not necessary.
6.5.3.5 An adequate means should be provided to avoid
a cross contamination of purge gases and the process
gases by accidental backflow.
6.5.3.6 Separation of purge gas and silane family gases
should not solely depend on check valves. A control
valve, such as a pneumatic valve placed before or after
the check valve, is preferred for isolating silane family
gases from other gases during procedures that might
allow reverse flow.
6.5.4 The purge gas for silane family gases should be
supplied from dedicated source containers.
NOTE 6: Some regional codes (e.g., Japan’s High Pressure
Gas Safety Law) require a purge gas source which is totally
separated from the purge gas source for oxidizer gas lines.
6.5.4.1 Purge lines from dedicated bulk supplies
(where allowed at all by the jurisdiction) should have
multi-level back-flow and pressure differential
protection to prevent potential back-flow of pyrophoric
gases into bulk systems.
NOTE 7: Back-flow into these bulk purge systems has been
known to generate ignitable mixtures when the inert gas is
exposed to atmosphere far from the source of contamination.
7 Education and Training
NOTE 8: It is important for managers as well as employees
to deepen their understanding of the characteristics of gases
that they handle, so as to ensure safe work practices. If
employees do not handle gases, this section is not applied.
7.1 Everyone who handles silane family gases should
be specially educated about the hazardous properties
and safe handling methods of these gases.
NOTE 9: Some jurisdictions (such as Japan) require that
users of “specialty high-pressure gases” provide special safety
education to their employees.
7.1.1 In regard to safety education and training, each
organization should create the curricula or obtain
approved curricula for education and training, assign a
person responsible for education and training, and
implement a periodic training plan.
7.1.2 Instructors should be persons who have sufficient
knowledge and experience about the hazards, use and
safe control of silane family gases.
NOTE 10: It may be necessary to request the assistance of
outside experts, depending on an organization’s capabilities.
7.1.3 Training should include safe use, handling,
hazardous properties and by-products and emergency
procedures of process gases as well as case studies of
past accidents.
7.1.4 Training should be performed periodically and
the training results documented.
7.2 Equipment and facilities suppliers, maintenance
service providers and users should establish education
curricula for job specific environmental, safety, and
health (ES&H) education programs, train their
personnel, and keep records or issue certificates.
7.3 Maintenance personnel should be fully trained in
their own areas of responsibility.
7.3.1 Maintenance personnel should understand the
overall design of facilities and equipment for silane
family gases.
7.3.2 Energy isolation (“lock out/tag out”) training
should be provided to all employees who are expected
to perform service or maintenance on silane family gas
systems.
7.4 Training curricula, should be requested from the
responsible party (constructor, facility manager, or
equipment manufacturer) as part of the purchase
specifications.
7.4.1 Each party should have qualified persons to train
personnel working in their facility.
NOTE 11: It may be necessary to request the assistance of
outside experts to perform training, depending on an
organization’s capabilities.
NOTE 12: Responsible persons for each party must be
trained as required by regulation.
7.5 Training of persons performing periodic
inspections should be provided to ensure the
inspections are performed and documented properly.
NOTE 13: Ideally, information on safe design practices and
accident investigation summaries should be freely shared
across the industry, so the information can be provided, as
part of education and training, to all personnel who could
potentially be exposed.
SEMI S18-1102 © SEMI 2002
6
8 Leak Detection and Alarm Systems
8.1 General
8.1.1 Audible and visual alarms should be provided at
a location where they can be seen and heard by
workers.
8.1.2 Remote audible and visual alarms should be
provided at a constantly attended location so that
appropriate actions can be taken.
8.2 Silane Family Gas Leak Detection Practice
8.2.1 Leak can be detected directly with leak sensors
(gas detectors) or indirectly with heat or fire detectors.
NOTE 14: Sensor types include electrochemical, chemically
treated tape, chemiluminescence, ionization detection, and
UV/IR.
8.2.1.1 Gas detection should be capable of detecting
the silane family gas down to a level at least one-half of
the TLV
®
level.
8.2.1.2 Ultraviolet/Infrared (UV/IR) detectors may be
allowed in some jurisdictions.
8.2.1.3 If UV/IR detection is used, it should be
designed to focus its detection beam across all areas
within the silane family gas exhausted enclosure where
leaks may occur.
8.2.1.3.1 UV/IR detection may be able to detect the
heat signature at levels lower than detectable limits for
gas detectors in some situations.
8.3 Leak Detection Installation
8.3.1 The location of detection points should be
determined by considering airflow patterns, specific
gravity of the gas, surrounding conditions or barriers,
and equipment height.
8.3.2 A leak detection system should be installed with
detection points at intervals appropriate to the detection
technology, or as required by regulation, for exhaust
ducts or cylinder storage.
8.3.3 Leak detectors should also be placed:
• in gas cabinets at locations that will detect leaks
from the piping system or the cylinder,
• in gas manifold boxes for silane family gas
distribution systems, and
• to detect leaks within equipment gas boxes for
equipment using silane family gases.
8.3.4 Leak detectors should be provided or specified
for locations where potential exposure is anticipated
during maintenance or service, when the normal
detection points might not detect a release.
8.3.5 The number and location of detection points
should be determined from detector capabilities, and the
area (or volume) to be monitored by each detector.
NOTE 15: A detection point is a collection opening for a
suction type gas leak detection system or a detector for a
diffusion-type gas-leak detection system.
8.3.5.1 The coverage should be tested after installation
to verify performance.
8.4 Leak Detection Systems Characteristics
8.4.1 Leak detection systems should be fail safe.
8.4.2 Effective detection that can generate warnings
and alarms when a given concentration of gas is
detected.
8.4.3 Warnings, which may not activate the audible
and visual alarms, should be generated at a
concentration level equal to or below OEL or as
specified in an applicable regulation of the country of
use. Alarms, which do activate notifications and audible
and visual alarms, should be activated at OEL
concentration level. If the OEL value is not available
for a silane family gas, or if the value is impractical for
the system, the lowest detectable concentration
technically practical or the concentration set by an
applicable regulation should be used.
8.4.4 The system should be capable of detecting the
target gas beginning at a level at least ½ of the OEL,
and continuing to at least ½ IDLH (Immediately
Dangerous to Life and Health) levels.
8.4.5 A 10% voltage variation should not produce
more than a 30% change in the indicated concentration.
8.4.6 Detection should be capable of detecting a
release, within one minute of exposure of the detection
point, to a leak, which has a concentration above the
concentration of the warning or alarm level.
8.4.7 The alarm should continue, even if the
concentration varies after detection, until it is manually
reset.
8.4.8 Activation of the leak detection system in a gas
cabinet should close the automatic cylinder shut off
valve referenced in Section 14.3.5.
8.5 Maintenance
8.5.1 Gas leak detection and alarm systems should be
periodically inspected and maintained following the
procedures provided by the gas detection system
manufacturer.
8.5.1.1 Inspection and maintenance should be
recorded.
SEMI S18-1102 © SEMI 2002
7
8.5.2 The system should be calibrated at intervals
specified by the detection system manufacturer.
8.5.3 Calibration should be performed frequently
enough to meet the accuracy criteria.
8.6 The gas leak detection system should have back up
power (e.g., UPS, emergency power, etc.) to maintain
its function during short-term power interruption or be
fail-safe. The back up power should be periodically
tested or inspected and the test or inspection
documented.
NOTE 16: The testing, the inspection, and the documentation
must be in accordance with any applicable regulations.
8.7 There may be a need for gas detection in some
exhaust treatment systems to detect breakthrough. See
the Exhaust Treatment System section for details.
NOTE 17: Gas detector monitoring in ducts may be required
by regulation or permits.
9 Fire Detection, Suppression, and Alarm
Systems
9.1 Alarms should connect to the facility under the
guidelines of SEMI S2.
9.2 Fire Detection and suppression system(s) where
used should be operational at all times, including when
equipment or facilities are shut down or in maintenance
modes. See SEMI S14 for guidelines for determining
whether such systems are appropriate and for designing
them.
EXCEPTION 1: Maintenance of the fire detection system.
EXCEPTION 2: Activation of the fire detection system
should not remove power from fire detection system and
safety systems.
9.3 Fire Detection and Suppression for Bulk Silane
Systems
9.3.1 An automatic fixed water spray system should be
provided for any bulk silane system for purposes of
cooling the system only.
9.3.1.1 The regulator station and control panel areas
should also be protected by a water spray system for
purposes of cooling the system only.
NOTE 18: Design density, area and duration should be
calculated appropriate to the surface area of the container
using a method such as the one provided in NFPA 318.
9.3.2 Activation of the optical flame detectors, manual
activation, or heat-link activators should initiate the
water spray system and should close emergency shutoff
valves (ESOVs). ESOVs should be located directly on
the source or on the piping, as close to the container as
possible.
9.4 Fire Detection and Suppression
9.4.1 Fires within valve manifold boxes (VMBs) may
impinge on other lines within the VMBs. If this is
assessed as an unacceptable risk, there may be a need
for fire protection.
9.4.2 When fire protection is installed, it should remain
active during all conditions such as maintenance and
service.
EXCEPTION: Maintenance of the fire protection system.
10 Emergency Response
10.1 Exhaust and abatement systems should be left
running during any emergency event, including fire in
the facility.
10.2 Evacuation of Personnel
10.2.1 Procedures for evacuation, as a result of a gas
leak, should be developed based on a hazard analysis
and should be appropriate to the level of hazard.
10.2.2 After an evacuation, no one should re-enter the
area until the exposure risk has been reduced to an
acceptable level.
10.2.3 All personnel in the facility should be trained
regarding proper evacuation procedures.
10.3 Leak Identification and Isolation
10.3.1 If the appropriate method of achieving a safe
situation is for a response team to enter, only authorized
and trained response personnel may enter to locate and
fix the leak.
10.3.2 If the leak location can be accurately
determined, the specific source supplying silane family
gases to the leak location should be automatically shut
down.
10.3.3 If the leak location cannot be accurately
determined, all of the systems supplying the area where
the leak was detected should be shut down.
10.3.4 Do not enclose a silane installation where
adequate exhaust flow can not remain during a leak.
This could lead to an explosion.
10.4 Recovery from Leaks
10.4.1 Trained personnel should investigate the
incident until the original or root cause is determined.
Systems should not be restarted until the safety of the
entire system is confirmed.
10.4.2 Sufficiently purge all affected systems with an
inert gas.