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SEMI S14-0704 © SEMI 2000, 2004 16 R3-6.3 Annual and sem i-annual maintenance sh ould be carried out by competent personnel with adequate training for the tasks in hand.

SEMI S14-0704 © SEMI 2000, 2004 15

the field review should concentrate on ensuring that

components are located so that they can see the hazard

without obstruction, including clear vision panels,

which may prevent detector from “seeing” the flame.

R3-3.5 Similarly detectors need to be sited so that they

will not experience normal process temperatures,

radiation or be exposed to chemical, liquid or particles

that could result in an accidental activation.

R3-3.6 Where linear heat detection cable is used it

should be located where it will not be exposed to levels

of ambient or process related heat that could trigger an

alarm signal. In addition the cable should be securely

attached to prevent it dislodging and coming into

contact with hot surfaces.

R3-3.7 Nozzle locations in many suppression systems

can be critical to ensuring functionality, reliability and

safety. For example, CO

nozzles incorrectly

positioned can result in chemical splashing or

dislodging product or quartzware. If nozzles are

exposed to chemical action including corrosive

chemicals, it is important that the materials are resistant

to the chemical

R3-3.8 Where automatic sprinkler heads are used, the

fusible link should be adequately protected from

chemical and mechanical attack.

R3-4 Commissioning Tests

R3-4.1 All installations should undergo a thorough

commissioning and acceptance test conducted by the

installer and witnessed by the owner or owner’s

representative.

R3-4.2 Functional Tests are essential, but not sufficient

to ensure that system will operate as in tended. The

types of problems that can be picked up by functional

testing are:

R3-4.2.1 Inability of detection system to detect as

intended,

R3-4.2.2 Inability of control system to receive signal

from individual detectors, and

R3-4.2.3 Inability of alarm panel to initiate system

discharge or send alarm signals to connected devices

and safety systems, e.g.,

• local or remote alarm panels,

• sounders & warning devices, and

• interlocks to equipment shutdown and safety

systems, EMO.

R3-4.3 Discharge Testing is the only way that we can

ensure that that a system will fulfill its intended

function. The types of problems that can be picked up

by discharge testing are:

R3-4.3.1 Lack of extinguishing agent

R3-4.3.2 Inability to transfer agent from supply to

nozzles due to:

• Blockages arising from incorrect equipment,

• Incomplete piping, loose fittings & supports, and

• Installation, design problems (e.g,. icing up of CO

pipes or nozzles).

R3-4.4 In many cases discharge testing within the

cleanroom environment is not considered acceptable or

practical. Accordingly, alternatives such as type testing

can prove that the design will provide the necessary

protection, but may need to be supplemented by a more

rigorous commissioning test of the final systems. Type

testing would involve the installation and discharge

testing of a system on a tool during manufacture or on a

mock up of the tool. The aim would be to prove that

distribution pipework and nozzles have been correctly

designed and that the concentration of agents and

distribution patterns from nozzles is acceptable. This

would be supplemented by additional tests on each

installation, including pressure tests of pipework and

“puff” tests to verify pipework integrity.

R3-5 Burn In

R3-5.1 In order to avoid unnecessary discharges, a

period of burn-in for the detection system is advisable.

This involves the detection system operating, enabling

detection of fires and initiation of alarms, but the

detection is not interlocked to shut down the process

equipment or initiate a discharge.

R3-5.2 A period of days or weeks may be appropriate

depending on the effect of an accidental activation of

the system in terms of interruption to processing,

damage to product or contamination of the

environment.

R3-6 Maintenance & Servicing

R3-6.1 Once systems are installed and commissioned it

is important that the routine inspection and maintenance

procedures recommended by manufacturers and those

required by codes and standards, are adequately

implemented.

R3-6.2 The inspection frequencies may need to be

modified if the ambient conditions can adversely affect

the protection systems. For example sprinkler heads

protecting corrosive fume exhaust ducts may need to be

inspected weekly or monthly until the appropriate

frequency for that particular system can be determined.

SEMI S14-0704 © SEMI 2000, 2004 16

R3-6.3 Annual and semi-annual maintenance should be

carried out by competent personnel with adequate

training for the tasks in hand.

SEMI S14-0704 © SEMI 2000, 2004 17

RELATED INFORMATION 4

DOCUMENTING EXPLOSION SAFETY FOR SEMICONDUCTOR

MANUFACTURING EQUIPMENT

NOTICE: This related information is not an official part of SEMI S14 and was derived from the work of a member

of the Fire Protection Task Force of the North American Environmental, Health, and Safety Committee. This

related information was approved for publication by 2/3 committee vote on July 17, 2003.

R4-1 Introduction

R4-1.1 The design of many semiconductor

manufacturing machines has to take account of the

hazard created by the presence of flammable liquids

and gases and as a result the designer will usually have

identified the hazards and put in place the necessary

mitigation and protection measures to provide a

satisfactory level of safety.

R4-1.2 This document is intended to assist equipment

designers and third party evaluators in documenting the

presence of explosion hazards and detailing how they

have integrated explosion safety into the design.

R4-1.3 There are specific requirements with regard to

the prevention and mitigation of explosion risks within

many jurisdictions. However the theory of explosion

prevention and mitigation transcends jurisdictional

boundaries. While this document arises out of the need

for some equipment to satisfy the European Union

ATEX Directive (94/9/EC), it has been developed in

such as way that it will not only meet the requirement

to document the principles of integrated explosion

safety (Essential Health and Safety Requirement 1.0),

but will provide information to authorities having

jurisdiction (AHJs) in many other parts of the world.

R4-2 Documentation

R4-2.1 For all equipment using flammable liquids or

gases an Explosion Risk Document (ERD) should be

developed and issued as an appendix to the SEMI S14

Fire Risk Assessment Internal Report. (The main

explosion hazards, risks and mitigation features should

already be documented in the S14 Final and Summary

Reports.)

R4-2.2 The ERD should demonstrate that the

equipment designer and manufacturer have adopted an

integrated approach to explosion safety adequately

mitigating the risk of an explosion.

R4-2.3 The structure of the document is flexible,

however a logical structure should be adopted such as

that suggested by the headings and sections of this

document, e.g.,

• Design Philosophy and Equipment Operation

Overview,

• Hazard Identification,

• Mitigation Measures Implemented & Protection

Systems Integrated, and

• Residual Explosion Risk.

R4-3 Design Philosophy and Equipment

Operation Overview

R4-3.1 The intended purpose of the equipment should

be stated, along with its operating environment.

R4-3.2 A functional and technical overview of the

process should be provided, where it relates to the

flammable and explosive chemicals and gases. This

should include significant process parameters including

temperature, pressure, and quantities of relevant

chemicals and gases. The operating conditions and

control system faults that influence explosion safety

should be described.

R4-3.3 The explosion protection design philosophy

should be thoroughly documented listing the design

standards applied, and any significant deviations.

R4-3.4 The classification of hazardous areas or zoning

outside and inside equipment should be described

indicating the classification system used (e.g., EN1127-

1, NFPA 497).

R4-3.5 Where components and equipment are within

or are related to areas classified as hazardous, they

should be documented including manufacturers’ details,

listings and approvals and confirmation that they have

been used within the scope of the approvals and

listings.

R4-4 Hazard Identification

R4-4.1 It is good practice to adopt a comprehensive

approach to hazard identification when designing for

explosive atmospheres, especially for complicated

equipment, protective systems and components. If a

structured approach to hazard identification and risk

assessment has been taken, for example, if during the

design process a HAZOP has been undertaken, the

HAZOP itself should form part of the documentation

supporting this section.