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SEMI F14-93 © SE MI 1993, 1999 2 equipment. 5.1.5 G a s Separation  Gas es t ha t are chem ically incompatible or belon g to dissimilar hazard classes should be s eparated. 6 Design Con sideration s 6.1 Regul atory Requ…

SEMI F14-93 © SEMI 1993, 19991

SEMI F14-93 (Reapproved 0699)

GUIDE FOR THE DESIGN OF GAS SOURCE EQUIPMENT

ENCLOSURES

This standard was technically reapproved by the Global Facilities Committee and is the direct responsibility

of the North American Facilities Committee. Current edition approved by the North American Regional

Standards Committee on December 18, 1998. Initially available on www.semi.org February 1999; to be

published June 1999. Originally published in 1993.

Editorial changes were made to sections 3.1.1, 6.2.1, and 6.2.2.

1 Purpose

1.1 This document summarizes gas source equipment

enclosure design considerations. It is intended for use

by manufacturers and purchasers.

2 Scope

2.1 Design considerations pertaining to gas source

equipment enclosures are described herein.

Modifications required to accommodate specific gases,

cylinders, or unusual applications (e.g., process

equipment) are not addressed.

3 Referenced Documents

3.1 Various codes and ordinances apply in different

municipalities. These documents must be followed for

the installation and operation of these systems. These

codes may include:

3.1.1 NFPA Standards

NFPA 13  Installation of Sprinkler Systems

NFPA 69  Explosion Prevention Systems

NFPA 70  National Electrical Code

NFPA 91  Exhaust Systems for Air Conveying

Materials

3.1.2 ICBO Model Code

Uniform Fire Code, 1991 Edition

3.1.3 SEMI Safety Guideline

SEMI S4  Safety Guideline for the Segregation/

Separation of Gas Cylinders Contained in Cabinets

3.1.4 Other Publications

Industrial Ventilation, A Manual of Recommended

Practice

National Fire Protection Association, Batterymarch Park, Quincy,

MA 02269

International Conference of Building Officials, 5360 South

Workman Mill Road, Whittier, CA 90601

BOCA National Building Code

BOCA National Fire Prevention Code

Standard Building Code

3.1.5 Local Ordinances

As applicable.

4 Terminology

4.1 gas cylinder  Usually means a high pressure

compressed gas cylinder governed by Department of

Transportation (DOT) regulations. It also refers to non-

DOT low pressure containers used for liquid product

having low vapor pressure.

4.2 gas source equipment enclosure (enclosure) 

An enclosure for the storage of gas containers and

associated equipment.

5 Functions

5.1 Five important functions are provided by an

enclosure and its associated safety devices.

5.1.1 Leaking Gas Containment  Personnel, equip-

ment, and the immediate working environment are

protected from the hazards of leaking gases.

5.1.2 Fire Protection  Personnel and equipment are

protected from the consequences of internal and

external fires.

5.1.3 Mechanical Protection  The cylinder and

associated equipment are protected from impact and

seismic forces. (For further information, see UFC 51,

Workstations and Fabrication Areas.)

5.1.4 Access Control  Unauthorized persons are

inhibited from using gases and operating associated

American Conference of Governmental Industrial Hygienists, 6500

Glenway Avenue, Building D-7, Cincinnati, OH 45211

Building Officials & Code Administrators International, Inc., 4051

West Flossmoor Road, Country Club Hills, IL 60477

Southern Building Code Congress International, 900 Montclair

Road, Birmingham, AL 35213

SEMI F14-93 © SEMI 1993, 1999 2

equipment.

5.1.5 Gas Separation  Gases that are chemically

incompatible or belong to dissimilar hazard classes

should be separated.

6 Design Considerations

6.1 Regulatory Requirements  T he enclosure should

conform to local, state, and federal regulations.

6.2 Materials

6.2.1 Enclosure top, sides, and doors should be

constructed of 2.7 mm (12 gage) or thicker cold-rolled

sheet steel or other suitable material so as to provide

adequate mechanical stability.

6.2.2 Floors should be constructed of cold-rolled sheet

steel or other suitable material, typically 3.4 mm (10

gage) or thicker, so as to adequately resist deformation

by the heaviest intended cylinder.

6.2.3 Windows and skylights should be 6.5 mm (0.25

in) thick wired safety glass or other suitable material.

6.2.4 All materials should be noncombustible.

6.3 Dimensions  The enclosure should completely

surround the gas cylinders and requisite accessory

equipment. The design should incorporate minimum

internal dimensions while still allowing safe and easy

access to cylinders and equipment.

6.3.1 Heights of shelves for short cylinders should be

adjustable so that cylinder valves and associated

equipment are readily accessible through the limited-

area access port.

6.3.2 Distances above cylinders should be adequate

for installation and operation of associated equipment.

6.4 Enclosure Interior Access

6.4.1 Door  A gasketed door should enable safe and

convenient installation and removal of intended

cylinders, and installation, removal, and maintenance of

associated equipment. The door should be self-closing

and self-latching. The threshold should not interfere

with cylinder installation and removal.

6.4.2 Limited-Area Access Port  The enclosure

should have one or more limited-area ports that enable

access to controls and associated equipment within the

enclosure without compromising the air velocity across

the face of the access port(s). The average air velocity

across the faces of access ports should not be less than

1 m/s (200 fpm); a minimum air velocity of 0.75 m/s

(150 fpm) should exist at any point.

6.4.2.1 Access ports should be self-closing.

6.4.3 Window  One or more windows should be

provided to enable observation of equipment within the

enclosure without compromising enclosure integrity.

6.4.4 Security  Lockable doors and access ports

should be provided when unauthorized access to the

enclosure interior must be precluded.

6.5 Ventilation  The enclosure should enable

removal of leaking gas by local exhaust ventilation.

The advantages of local exhaust ventilation over

general ventilation are more fully described in NFPA

69, NFPA 91, and in Industrial Ventilation.

6.5.1 Exhaust Connection  The enclosure should

enable connection to an exhaust system that will handle

the required exhaust at an average duct velocity that

does not exceed 8.5 m/s (1,700 fpm). The total exhaust

flow includes that across open access ports as well as

that through any supplementary air inlets.

6.5.2 Air Flow Path  In addition to access ports, the

enclosure should include an air inlet located at the

extremity of the enclosure opposite from the exhaust

connection, so that ventilation of the entire enclosure is

provided. The air flow path should adequately

scavenge gas from all regions within the enclosure.

6.5.2.1 Structures (e.g., brackets or shelves) within the

enclosure should not adversely affect exhaust

capability.

6.5.2.2 Gaskets should be provided on all doors,

access ports, and other penetrations.

6.6 Fire Protection

6.6.1 Sprinklers  Provisions for internal sprinklers

should be made when necessary.

6.6.1.1 Sprinklers should be capable of providing

adequate cooling to maintain cylinders and associated

equipment at a temperature that will not actuate relief

devices in the event of an internal or external fire.

6.6.1.2 Sprinkler actuation temperature should be

greater than the anticipated maximum operating

temperature of the enclosure interior under typical

operating conditions, but less than the cylinder pressure

relief device actuation temperature.

6.6.1.3 When the enclosure may be exposed to

corrosive atmospheres, corrosion-resistant sprinklers

should be provided. (For further information, see

NFPA 13, Corrosion-Resistant, Wax-Coated, or

Similar Sprinklers.)

6.7 Mechanical Stabilization

6.7.1 Provision for anchoring the enclosure to stable

architectural elements should be made.

6.7.2 Fasteners should meet anticipated seismic loads

in seismically active areas.

6.7.3 A means of securing each cylinder within the

enclosure should be provided.

6.8 Surface Finishes

6.8.1 All exterior surfaces and equipment should be

treated or finished to resist attack by weather elements.

6.8.2 Interior surfaces and equipment should be

treated or finished to resist corrosive or solvent effects.

6.8.3 All surfaces should be free of burrs, sharp edges,

and other flaws that could injure users.

6.9 Interior Illumination  Illumination of the

enclosure interior should be adequate for safe operation

of contained equipment. When ambient light is

inadequate, several approaches may be taken to provide

additional lighting:

6.9.1 A skylight may be provided.

6.9.2 With nonflammable gases, internal electric lights

may be provided.

6.9.3 With flammable gases, power cables should not

penetrate the enclosure interior except as provided for

Class I, Division 2 locations (NEC, Article 501). Either

internal explosion-proof lights may be provided, or

external standard lights may project through an

unopenable window.

6.9.4 All interior surfaces should reflect light

efficiently.

6.10 Labels

6.10.1 Gas Labels  A label clearly displaying the

chemical formula and common name of the gas should

be attached to the enclosure exterior surface; its color

should contrast with that of the enclosure.

6.10.2 Hazard Warning Labels  A label clearly

stating requisite hazard warnings should be

mechanically attached to the enclosure exterior surface

in accordance with local building code requirements.

6.10.3 Information Labels  A label providing

important specific information such as, but not limited

to, emergency contacts, telephone numbers, manifold

schematics, and first aid recommendations should be

attached to the enclosure exterior surface.

NOTICE: These standards do not purport to address

safety issues, if any, associated with their use. It is the

responsibility of the user of these standards to establish

appropriate safety and health practices and determine

the applicability of regulatory limitations prior to use.

SEMI makes no warranties or representations as to the

suitability of the standards set forth herein for any

particular application. The determination of the

suitability of the standard is solely the responsibility of

the user. Users are cautioned to refer to manufacturer’s

instructions, product labels, product data sheets, and

other relevant literature respecting any materials

mentioned herein. These standards are subject to

change without notice.

The user’s attention is called to the possibility that

compliance with this standard may require use of

copyrighted material or of an invention covered by

patent rights. By publication of this standard, SEMI

takes no position respecting the validity of any patent

rights or copyrights asserted in connection with any

item mentioned in this standard. Users of this standard

are expressly advised that determination of any such

patent rights or copyrights, and the risk of infringement

of such rights, are entirely their own responsibility.

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the contents in whole or in part is forbidden without express written

consent of SEMI.