PREAMBLE (NOT PART OF THE STANDARD)

In order to promote public education and public safety, equal justice for all, a better informed citizenry, the rule of law, world trade and world peace, this legal document is hereby made available on a noncommercial basis, as it is the right of all humans to know and speak the laws that govern them.

END OF PREAMBLE (NOT PART OF THE STANDARD)

CGA S-7—2005
METHOD FOR SELECTING PRESSURE RELIEF DEVICES FOR COMPRESSED GAS MIXTURES IN CYLINDERS

FOURTH EDITION

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i

PLEASE NOTE:

The information contained in this document was obtained from sources believed to be reliable and is based on technical information and experience currently available from members of the Compressed Gas Association, Inc. and others. However, the Association or its members, jointly or severally, make no guarantee of the results and assume no liability or responsibility in connection with the information or suggestions herein contained. Moreover, it should not be assumed that every acceptable commodity grade, test or safety procedure or method, precaution, equipment or device is contained within, or that abnormal or unusual circumstances may not warrant or suggest further requirements or additional procedure.

This document is subject to periodic review, and users are cautioned to obtain the latest edition. The Association invites comments and suggestions for consideration. In connection with such review, any such comments or suggestions will be fully reviewed by the Association after giving the party, upon request, a reasonable opportunity to be heard. Proposed changes may be submitted via the Internet at our website, www.cganet.com.

This document should not be confused with federal, state, provincial, or municipal specifications or regulations; insurance requirements; or national safety codes. While the Association recommends reference to or use of this document by government agencies and others, this document is purely voluntary and not binding unless adopted by reference in regulations.

A listing of all publications, audiovisual programs, safety and technical bulletins, and safety posters is available via the Internet at our website at www.cganet.com. For more information contact CGA at Phone: 703-788-2700, ext. 799. E-mail: customerservice@cganet.com.

Work Item 06-48
Cylinder Valve Committee

NOTE—Technical changes from the previous edition are underlined.

NOTE—Appendices A and B (Normative) are requirements.

NOTE—Appendix C (Informative) is for information only.

FOURTH EDITION: 2005
THIRD EDITION: 2003
SECOND EDITION: 1996
FIRST EDITION: 1989
© 2005 The Compressed Gas Association, Inc. All rights reserved.

All materials contained in this work are protected by United States and international copyright laws. No part of this work may be reproduced or transmitted in any form or by any means, electronic or mechanical including photocopying, recording, or any information storage and retrieval system without permission in writing from The Compressed Gas Association, Inc. All requests for permission to reproduce material from this work should be directed to The Compressed Gas Association, Inc., 14501 George Carter Way, Suite 103, Chantilly VA 20151 You may not alter or remove any trademark, copyright or other notice from this work.

ii
1) The temperature of the cryogenic gases is always below –130 °F (–90 °C).
2) If pressure at 130 °F (54 °C) is over 600 psi (4140 kPa), use digit 1.
3) When separate outlet for liquid withdrawal is specified.
Contents Page
1 Introduction 1
2 Scope 1
3 Definitions 2
4 Types of pressure relief devices 2
  4.1 Type CG-1 2
  4.2 Type CG-2 2
  4.3 Type CG-3 3
  4.4 Type CG-4 3
  4.5 Type CG-5 3
  4.6 Type CG-7 3
5 Description of method and procedures 4
  5.1 Algorithm 4
  5.2 Responsibility for selection of the pressure relief device 4
  5.3 Guidelines for use of the algorithm 4
  5.4 Procedure for assigning a pressure relief device for a mixture 5
6 References 32
Figures
Figure 1—Algorithm for gas mixtures (U.S. customary units) 6
Figure 2—Algorithm for gas mixtures (SI units) 7
Examples
Example 1—100 ppm hydrogen, balance nitrogen (U.S. customary units) 9
Example 2—5% trimethylamine, balance sulfur hexafluoride (U.S. customary units) 11
Example 3—5% trimethylamine, balance sulfur hexafluoride (SI units) 13
Example 4—0.5% oxygen, 0.5% nitrogen, balance methane (U.S. customary units) 15
Example 5—12% ethylene oxide, balance dichlorodifluoromethane (R12) (U.S. customary units) 17
Example 6—5% carbon dioxide, balance oxygen (DOT 3AA2015 cylinder) (U.S. customary units) 19
Example 7—5% carbon dioxide, balance oxygen (DOT 3E1800 cylinder) (U.S. customary units) 21
Example 8—Multicomponent gas mixtures (U.S. customary units) 23
Example 9—20% arsine, balance hydrogen (U.S. customary units) 25
Example 10—2% arsine, balance hydrogen (U.S. customary units) 27
Example 11—0.2% arsine, balance hydrogen (U.S. customary units) 29
Example 12—5% arsine, 10% phosphine, balance hydrogen (U.S. customary units) 31
Appendices
Appendix A—FTSC numerical code for gas classification (Normative) 33
Appendix B—List of gases (Normative) 34
Appendix C—Sample worksheet (Informative) 39
iii iv

1 Introduction

This publication presents a method for selecting pressure relief devices (PRDs) for compressed gas mixtures packaged in cylinders having water capacities of 1000 lb (454 kg) (see U.S. Department of Transportation [DOT] Title 49 of the U.S. Code of Federal Regulations [49 CFR] Part 173.301 [f]). This standard also applies to DOT 3AX, 3AAX, and 3T cylinders having water capacities over 1000 lb (454 kg) that comply with the specifications, charging, and maintenance regulations of DOT or the corresponding specifications and regulations of Transport Canada (TC) [1, 2].1

The task is more involved than the method for determining the appropriate valve outlet connections for gas mixtures. For the latter, as described in CGA V-7, Standard Method of Determining Cylinder Valve Outlet Connections for Industrial Gas Mixtures, mixture component rating numbers are assigned to the various compressed gases based on the physical properties of the gases, i.e., flammability, toxicity, state of the gas, and corrosiveness [3]. The higher the mixture component rating number (1 through 6), the more influential that gas becomes in determining the outlet connection for the mixture in which that gas is a component.

Valve outlet connection assignments are broadly separated into connections for groups of gases having similar properties such as high and low pressure, flammability, corrosivity, toxicity, and inertness. Since 1978 this system has proven satisfactory in avoiding hazardous connections.

The physical characteristics of a mixture consisting of several pure gases could be dramatically different depending on the concentration of each gas in the mixture. Depending on these concentrations, a mixture could be flammable or nonflammable, toxic or nontoxic, liquified or nonliquefied, corrosive or noncorrosive. Since the mixture is released to the atmosphere when the relief device functions, the characteristics of the escaping gas mixture must be well defined.

It was concluded that a method would have to be established for assigning the proper relief device for each mixture, just as is done for pure gases in CGA S-1.1, Pressure Relief Device Standards—Part 1Cylinders for Compressed Gases [4]. To use this method, the proper FTSC code must be determined (see Appendix A). In some cases, determining the proper FTSC number is straightforward. However, in other cases the appropriate FTSC number is not as obvious, and in most cases this determination is the responsibility of the gas mixture producer. It must be understood that some of the considerations made in determining the selection of the PRD used in this publication are based on experience.

The method outlined in this publication is designed to handle the proliferation of mixtures entering the commercial market.

The continued use of previously recognized and installed devices is not restricted by this edition of the standard. However, if a PRD is replaced, the new device shall meet the requirements of this standard.

2 Scope

This method is applicable to the determination of the proper PRD to use with compressed gas mixtures in cylinders defined in Section 1.

This method is limited to those compressed gas mixtures with known flammability, toxicity (LC50), state, and corrosivity. In addition, the DOT/TC rating and dimensions of the cylinder and the final pressure must be known.

For the selection of PRDs for a single component compressed gas, see CGA S-1.1 [4]. For multicomponent compressed gases (mixtures), the method for selection of relief devices in this publication should be used. Where a mixture is predominantly made up of a single component in a mixture, the gas producer shall determine whether the properties of this mixture dictate it being treated as a single component compressed gas or a gas mixture.

1 References are shown by bracketed numbers and are listed in order of appearance in the reference section.

1

3 Definitions

For the purpose of this standard, the following definitions apply.

3.1 Algorithm

Series of formatted questions that when answered in sequence will result in the selection of one or more PRDs.

3.2 Blanketing or pressurizing

Pressurization of the vapor space above a liquefied gas or liquid for the purpose of liquid withdrawal.

3.3 Final pressure

Charged settled pressure at 70 °F (21.1 °C).

3.4 Compressed gas

Any material that exerts in a container an absolute pressure of at least 40.6 psia (280 kPa) at 68 °F (20 °C).2

3.5 Gas mixture

Purposeful combination of two or more commodities resulting in a compressed gas.

3.6 Producer

Site where the compressed gas mixture is packaged into cylinders and the personnel who perform the work.

3.7 Lethal concentration fifty (LC50)

Concentration of a substance in air for which exposure for a specified length of time is expected to cause the death of 50% of the entire defined experimental animal population.

NOTE—See CGA P-20, Standard for the Classification of Toxic Gas Mixtures [6].

3.8 Hazard zone A

Material with a toxicity LC50 less than or equal to 200 ppm.

3.9 Hazard zone B

Material with a toxicity LC50 greater than 200 ppm and less than or equal to 1000 ppm.

3.10 Hazard zone C

Material with a toxicity LC50 greater than 1000 ppm and less than or equal to 3000 ppm.

3.11 Hazard zone D

Material with a toxicity LC50 greater than 3000 ppm and less than or equal to 5000 ppm.

4 Types of pressure relief devices

Types of PRDs are designated as follows:

4.1 Type CG-1

A rupture disk.

4.1.1 Limitations

Since this is a pressure-operated device designed to release the entire content of the container, there is no way to prevent the complete release of the content, either as a result of normal functioning or premature rupture of the device.

2 kPa shall indicate gauge pressure unless otherwise noted as (kPa, abs) for absolute pressure or (kPa, differential) for differential pressure. All kPa values are rounded off per CGA P-11, Metric Practice Guide for the Compressed Gas Industry [5].

2

4.2 Type CG-2

A fusible plug using a fusible alloy with yield temperature not over 170 °F (76.7 °C) or less than 157 °F (69.4 °C). Nominal yield temperature is 165 °F (73.9 °C).

4.2.1 Limitations

Since this is a thermally operated device, it does not protect against overpressure from improper charging practices. This device releases the entire lading of the container when it functions, and is limited to use on cylinders of 500 psig (3450 kPa) service pressure or less. This device may be used in higher service pressure cylinders provided that the product pressure does not exceed 500 psig (3450 kPa) at 68 °F (20 °C) and the device type is mandated by this standard or TC regulations.

4.3 Type CG-3

A fusible plug using a fusible alloy with yield temperature not over 224 °F (106.7 °C) or less than 208 °F (97.8 °C). Nominal yield temperature is 212 °F (100 °C).

4.3.1 Limitations

Same as for CG-2 (see 4.2.1).

4.4 Type CG-4

A combination rupture-disk/fusible-plug device using a fusible alloy with yield temperature not over 170 °F (76.7 °C) or less than 157 °F (69.4 °C). Nominal yield temperature is 165 °F (73.9 °C).

4.4.1 Limitations

Since this device is a combination device, it requires both excessive pressure and temperature to cause it to operate. This device will not function due to pressure unless the fusible metal is melted out first. Such a combination device cannot prevent an improperly filled (overfilled) cylinder from rupturing due to hydrostatic pressure at room temperature or any temperature below the melting temperature of the fusible metal, as will devices that contain only a rupture disk (CG-1). There is no way to prevent the complete release of the content when this device functions.

4.5 Type CG-5

A combination rupture-disk/fusible-plug device using a fusible alloy with yield temperature not over 224 °F (106.7 °C) or less than 208 °F (97.8 °C). Nominal yield temperature is 212 °F (100 °C).

4.5.1 Limitations

Same as for CG-4 (see 4.4.1).

4.6 Type CG-7

A pressure relief valve.

4.6.1 Limitations

This device maintains the pressure in the container at a limit as determined by the set pressure of the valve and thus does not protect against rupture of the container when the application of heat weakens the container to the point where its rupture pressure is less than the operating pressure of the device.

WARNING: PRDs might not prevent rupture of a cylinder under all conditions of fire exposure. When the heat transferred to the cylinder is localized, intensive, and remote to the relief device, or where the fire builds extremely rapidly such as in an explosion and is of very high intensity, the cylinder can weaken sufficiently to rupture before the relief device operates or while it is operating.

3

5 Description of method and procedures

5.1 Algorithm

The algorithm has been designed to assist the gas mixture producer to quickly and correctly determine the appropriate PRD(s) for gas mixtures. The algorithm is shown in Figure 1 (U.S. customary units) and Figure 2 (SI units). Application of the algorithm is illustrated for selected gas mixtures in Examples 1-12.

5.2 Responsibility for selection of the pressure relief device

The responsibility for the selection of the PRD lies with the gas mixture producer. Although the algorithm does permit a degree of flexibility in the selection of the relief device for some cylinders, the flammability, toxicity (LC50), state, and corrosivity of the mixture shall be determined first. Appendix A provides the definitions of the FTSC codes. Appendix B lists the codes for most of the gases that are commonly used in mixtures.

5.3 Guidelines for use of the algorithm

The following guidelines and constraints govern the use of the algorithm:

– The final mixture properties, i.e., flammability, toxicity, state of the gas, corrosiveness, and final pressure are known by the gas mixture producer.

– The producer shall determine the mixture’s flammability. As used in the algorithm, “Flammable” means having an “F” rating of 2, 3, or 5.

– The producer shall determine the mixture’s toxicity. In accordance with DOT (49 CFR 173.115), the toxicity of the mixture can be calculated from the concentrations and toxicity of the components as follows (see CGA P-20 for additional details regarding mixture toxicity calculations) [6]:

Image

Where:

n                       = Number of toxic components

Concentrationi   = Concentration of the ith toxic component, expressed as a decimal fraction of the whole, e.g., 0.05 for a 5% mixture and 5 × 10–6 for a 5 ppm mixture. This number is dimensionless

LC50, i                = LC50 of the ith toxic component, in ppm

LC50, mix            = LC50 of the mix, in ppm

For a mixture with a single toxic component, this simplifies to:

Image

– As used in the algorithm, “Corrosive” means having a “C” rating of 1 or greater.

– Other definitions conform with those of DOT or TC if applicable.

– Pressurization of the vapor space above a condensed liquid for the purpose of withdrawal does not constitute a gas mixture.

– If a 110% fill is authorized, only the CG-1 device is allowed.

4

– When the CG-2 device is indicated, it allows use of the CG-3 device where the final mixture properties permit. Likewise when the CG-4 device is indicated, the CG-5 device may be used where the final mixture properties permit.

NOTE—The decision of whether the CG-2 or CG-3 device is used as well as whether the CG-4 or CG-5 device is used shall be made by the gas mixture producer as authorized by the latest edition of CGA S-1.1 based on the producer’s classification of the final mixture according to its properties [4].

– Where two or more types of PRDs are indicated, only one of them is required. Care should be taken that the selection made conforms to all requirements in 49 CFR and CGA S-1.1 [1, 4]. For example, see CGA S-1.1 regarding the requirements for relief devices at both ends of the cylinder if the cylinder length exceeds 30 in (762 mm) [4].

5.4 Procedure for assigning a pressure relief device for a mixture

With an understanding of the guidelines in 5.3, the procedures below shall be followed to assign a PRD for a mixture (see Appendix C for a worksheet format):

  1. In the worksheet, list the components and concentration thereof in the proposed gas mixture in the first two columns;
  2. Enter the FTSC code for each mixture component directly from Appendix B in the next four additional columns;
  3. Add the LC50 in the last column from Appendix B, if available;
  4. Verify that the DOT/TC rating and dimensions of the cylinder to be filled as well as the final pressure of the mixture are compatible with each other and are in compliance with pertinent regulations contained in 49 CFR 173.301(a)(8) [1];
  5. Calculate the toxicity (T) of the mixture as described in 5.3 and assign F, S, and C codes based on experience and the properties of the components of the mixture;
  6. Using the mixture’s FTSC code established in step e), answer each question, beginning at the “Start” of the algorithm, until a determination of the proper PRD is accomplished; and
  7. Size the PRD in accordance with the requirements of the latest edition of CGA S-1.1 [4].
5

Figure 1—Algorithm for gas mixtures (U.S. customary units)

Figure 1—Algorithm for gas mixtures (U.S. customary units)

6

Figure 2—Algorithm for gas mixtures (SI units)

Figure 2—Algorithm for gas mixtures (SI units)

7

Worksheet for Example 1
100 ppm hydrogen, balance nitrogen
(U.S. customary units)

  COMPONENTS CONCENTRATION F T S C LC50
1. Hydrogen 100 ppm 2 1 6 0 > 5000 ppm
2. Nitrogen Balance 0 1 6 0 > 5000 ppm

 

DOT CYLINDER RATING: 3AA2015  
FINAL PRESSURE: 2000 psig at 70 °F  
2226 psig at 130 °F  
DIMENSIONS: 9 in diameter 51 in length

 

MIXTURE FTSC: 0 1 6 0
MIXTURE LC50: > 5000 ppm, no Zone A component

STEPS ON ALGORITHM: (See Example 1)

  1. Mixture LC50 is > 200 ppm.
  2. Mixture is nonliquefied but pressure is > 300 psig.
  3. Cylinder has an O.D. > 4.5 in.
  4. Mixture nonliquefied at 70 °F.
  5. Mixture is nonflammable (as determined by gas producer).
  6. Pressure is > 500 psig.
  7. Mixture is not corrosive (as determined by gas producer).
  8. PRD is CG-1 or CG-4.

OBSERVATIONS:

  1. Either device is suitable.
  2. Since the length of the cylinder is < 65 in, only one PRD is required.
  3. The pressure in the cylinder at 130 °F will be < 5/4 times the service pressure of 2015 psig.
8

Example 1—100 ppm hydrogen, balance nitrogen (U.S. customary units)

Example 1—100 ppm hydrogen, balance nitrogen (U.S. customary units)

9

Worksheet for Example 2
5% trimethylamine, balance sulfur hexafluoride
(U.S. customary units)

  COMPONENTS CONCENTRATION F T S C LC50
1. Trimethylamine 5% 2 1 0 2 7000 ppm
2. Sulfur hexafluoride Balance 0 1 0 0 > 5000 ppm

 

DOT CYLINDER RATING: 3AA2015  
FINAL PRESSURE: 250 psig at 70 °F  
278 psig at 130 °F  
DIMENSIONS: 9 in diameter 51 in length

Image

MIXTURE FTSC: 2 1 0 2
MIXTURE LC50: 140 000 ppm, no Zone A component

STEPS ON ALGORITHM: (See Example 2)

  1. Mixture LC50 is > 200 ppm.
  2. Mixture is nonliquefied and pressure is < 300 psig.
  3. Cylinder is not DOT 39.
  4. No PRD is required.

OBSERVATIONS:

No PRD is required.

10

Example 2—5% trimethylamine, balance sulfur hexafluoride (U.S. customary units)

Example 2—5% trimethylamine, balance sulfur hexafluoride (U.S. customary units)

11

Worksheet for Example 3
5% trimethylamine, balance sulfur hexafluoride
(SI units)

  COMPONENTS CONCENTRATION F T S C LC50
1. Trimethylamine 5% 2 1 0 2 7000 ppm
2. Sulfur hexafluoride Balance 0 1 0 0 > 5000 ppm

 

DOT CYLINDER RATING: 3AA2015  
FINAL PRESSURE: 1720 kPa at 21.1 °C  
1916 kPa at 54.4 °C  
DIMENSIONS: 229 mm diameter 1295 mm length

Image

MIXTURE FTSC: 2 1 0 2
MIXTURE LC50: 140 000 ppm, no Zone A component

STEPS ON ALGORITHM: (See Example 3)

  1. Mixture LC50 is > 200 ppm.
  2. Mixture is nonliquefied and pressure is < 2070 kPa.
  3. Cylinder is not DOT 39.
  4. No PRD is required.

OBSERVATIONS:

No PRD is required.

12

Example 3—5% trimethylamine, balance sulfur hexafluoride (SI units)

Example 3—5% trimethylamine, balance sulfur hexafluoride (SI units)

13

Worksheet for Example 4
0.5% oxygen, 0.5% nitrogen, balance methane
(U.S. customary units)

  COMPONENTS CONCENTRATION F T S C LC50
1. Oxygen 0.5% 4 0 6 0 > 5000 ppm
2. Nitrogen 0.5% 0 1 6 0 > 5000 ppm
3. Methane Balance 2 1 6 0 > 5000 ppm

 

DOT CYLINDER RATING: 3AX2400  
FINAL PRESSURE: 2400 psig at 70 °F  
2671 psig at 130 °F  
DIMENSIONS: 9.5 in diameter 252 in length

All mixture components have LC50 values above 5000 ppm, but oxygen is < 19.5%, therefore the T code is 1.

MIXTURE FTSC: 2 1 6 0
MIXTURE LC50: >5000 ppm, no Zone A component

STEPS ON ALGORITHM: (See Example 4)

  1. Mixture LC50 is > 200 ppm.
  2. Mixture is nonliquefied but pressure > 300 psig.
  3. Cylinder has an O.D. > 4.5 in.
  4. Mixture is nonliquefied at 70 °F.
  5. Mixture is flammable (as determined by gas producer).
  6. Pressure > 500 psig.
  7. PRD is CG-4.

OBSERVATIONS:

  1. Since the length of the cylinder is > 65 in, a PRD is required at each end.
  2. The pressure in the cylinder at 130 °F is < 5/4 times the service pressure of 2400 psig.
  3. Since the mixture has been deemed to be predominantly methane, then CGA S-1.1 permits a CG-1, CG-4, or CG-5 device [4]. The CG-7 device may not be used since the final fill pressure is > 500 psig.
14

Example 4—0.5% oxygen, 0.5% nitrogen, balance methane (U.S. customary units)

Example 4—0.5% oxygen, 0.5% nitrogen, balance methane (U.S. customary units)

15

Worksheet for Example 5
12% ethylene oxide, balance dichlorodifluoromethane (R12)
(U.S. customary units)

  COMPONENTS CONCENTRATION F T S C LC50
1. Ethylene oxide 12% 5 2 0 0 2920 ppm
2. Refrigerant-12 Balance 0 1 0 0 > 5000 ppm

 

DOT CYLINDER RATING: 4BA240  
FINAL PRESSURE 70 psig at 70 °F  
78 psig at 130 °F  
DIMENSIONS: 10.5 in diameter 55 in length

Image

MIXTURE FTSC: 0 1 2 0
MIXTURE LC50: > 5000 ppm, no Zone A component

STEPS ON ALGORITHM: (See Example 5)

  1. Mixture LC50 is > 200 ppm.
  2. Mixture is liquefied but pressure is < 300 psig.
  3. Cylinder has an O.D. > 4.5 in.
  4. Mixture is liquefied at 70 °F.
  5. Mixture is nonflammable (as determined by gas producer).
  6. Pressure is < 500 psig.
  7. Mixture is not corrosive (as determined by gas producer).
  8. PRD is either CG-1 or CG-7.

OBSERVATIONS:

  1. Either device is suitable.
  2. Since the length of the cylinder is < 65 in, only one PRD is required.
  3. The pressure in the cylinder at 130 °F is < 5/4 times the service pressure of 240 psig.
16

Example 5—12% ethylene oxide, balance dichlorodifluoromethane (R12) (U.S. customary units)

Example 5—12% ethylene oxide, balance dichlorodifluoromethane (R12) (U.S. customary units)

17

Worksheet for Example 6
5% carbon dioxide, balance oxygen
(DOT 3AA2015 cylinder)
(U.S. customary units)

  COMPONENTS CONCENTRATION F T S C LC50
1. Carbon Dioxide 5% 0 1 6 0 > 5000 ppm
2. Oxygen Balance 4 0 6 0 > 5000 ppm

 

DOT CYLINDER RATING: 3AA2015  
FINAL PRESSURE: 2000 psig at 70 °F  
2226 psig at 130 °F  
DIMENSIONS: 9 in diameter 51 in length

ALL mixture components have LC50 values above 5000 ppm, and oxygen is > 19.5%, therefore the T code is 0.

MIXTURE FTSC: 4 0 6 0
MIXTURE LC50: > 5000 ppm, no Zone A component

STEPS ON ALGORITHM: (See Example 6)

  1. Mixture LC50 is > 200 ppm.
  2. Mixture is nonliquefied but pressure > 300 psig.
  3. Cylinder has an O.D. > 4.5 in.
  4. Mixture is nonliquefied at 70 °F.
  5. Mixture is nonflammable (as determined by gas producer).
  6. Pressure is > 500 psig.
  7. Mixture is not corrosive (as determined by gas producer).
  8. PRD is CG-1 or CG-4.

OBSERVATIONS:

  1. Either device is suitable.
  2. As the length of the cylinder is < 65 in, only one PRD is required.
  3. The pressure in the cylinder at 130 °F is < 5/4 times the service pressure of 2015 psig.
18

Example 6—5% carbon dioxide, balance oxygen (DOT 3AA2015 cylinder) (U.S. customary units)

Example 6—5% carbon dioxide, balance oxygen (DOT 3AA2015 cylinder) (U.S. customary units)

19

Worksheet for Example 7
5% carbon dioxide, balance oxygen
(DOT 3E1800 cylinder)
(U.S. customary units)

  COMPONENTS CONCENTRATION F T S C LC50
1. Carbon dioxide 5% 0 1 6 0 > 5000 ppm
2. Oxygen Balance 4 0 6 0 > 5000 ppm

 

DOT CYLINDER RATING: 3E1800  
FINAL PRESSURE: 1750 psig at 70 °F  
1948 psig at 130 °F  
DIMENSIONS: 2 in diameter 12 in length

All mixture components have LC50 values above 5000 ppm and oxygen is > 19.5%, therefore the T code is 0.

MIXTURE FTSC: 4 0 6 0
MIXTURE LC50: > 5000 ppm, no Zone A component

STEPS ON ALGORITHM: (See Example 7)

  1. Mixture LC50 is > 200 ppm
  2. Mixture is nonliquefied but pressure > 300 psig.
  3. Cylinder O.D. < 4.5 in, length < 12 in, final pressure < 1800 psig and not DOT 39.
  4. No PRD is required.

OBSERVATIONS:

The pressure in the cylinder at 130 °F is < 5/4 times the service pressure of 1800 psig.

20

Example 7—5% carbon dioxide, balance oxygen (DOT 3E1800 cylinder) (U.S. customary units)

Example 7—5% carbon dioxide, balance oxygen (DOT 3E1800 cylinder) (U.S. customary units)

21

Worksheet for Example 8
Multicomponent gas mixtures
(U.S. customary units)

  COMPONENTS CONCENTRATION F T S C LC50
1. Methane 4% 2 1 6 0 > 5000 ppm
2. Propane 4% 2 1 0 0 > 5000 ppm
3. Ethane 4% 2 1 1 0 > 5000 ppm
4. Carbon Monoxide 4% 2 2 6 0 3760 ppm
5. Hydrogen 4% 2 1 6 0 > 5000 ppm
6. Oxygen 5.5% 4 0 6 0 > 5000 ppm
7. Nitrogen Balance 0 1 6 0 > 5000 ppm

 

DOT CYLINDER RATING: 3AA2015  
FINAL PRESSURE: 1650 psig at 70 °F  
1837 psig at 130 °F  
DIMENSIONS: 9 in diameter 51 in length

Image

MIXTURE FTSC: 2 1 6 0
MIXTURE LC50: 94 000 ppm, no Zone A component

STEPS ON ALGORITHM: (See Example 8)

  1. Mixture LC50 is > 200 ppm.
  2. Mixture is nonliquefied, pressure > 300 psig.
  3. Cylinder has an O.D. > 4.5 in.
  4. Mixture is nonliquefied at 70 °F.
  5. Mixture is flammable (as determined by gas producer).
  6. Pressure is > 500 psig.
  7. PRD is CG-4.

OBSERVATIONS:

  1. Since the length of the cylinder is < 65 in, only one PRD is required.
  2. The pressure in the cylinder at 130 °F is < 5/4 times the service pressure of 2015 psig.
22

Example 8—Multicomponent gas mixtures (U.S. customary units)

Example 8—Multicomponent gas mixtures (U.S. customary units)

23

Worksheet for Example 9
20% arsine, balance hydrogen
(U.S. customary units)

  COMPONENTS CONCENTRATION F T S C LC50
1. Arsine 20% 2 3 0 0 20 ppm
2. Hydrogen Balance 2 1 6 0 > 5000 ppm

 

DOT CYLINDER RATING: 3AA2015  
FINAL PRESSURE: 600 psig at 70 °F  
669 psig at 130 °F  
DIMENSIONS: 9 in diameter 15 in length

Both components are flammable, so the mixture F code is 2 (as determined by the mixture producer).

Image

The mixture is a nonliquefied gas between 600 psig and 3000 psig, so the mixture S code is 6 (as determined by the mixture producer).

Neither component is corrosive, so the mixture C code is 0 (as determined by the mixture producer).

MIXTURE FTSC: 2 3 6 0
MIXTURE LC50: 100 ppm

STEPS ON ALGORITHM: (See Example 9)

  1. Mixture LC50 is ≤ 200 ppm.
  2. PRD is prohibited.
24

Example 9—20% arsine, balance hydrogen (U.S. customary units)

Example 9—20% arsine, balance hydrogen (U.S. customary units)

25

Worksheet for Example 10
2% arsine, balance hydrogen
(U.S. customary unit)

  COMPONENTS CONCENTRATION F T S C LC50
1. Arsine 2% 2 3 0 0 20 ppm
2. Hydrogen Balance 2 1 6 0 > 5000 ppm

 

DOT CYLINDER RATING: 3AA2015  
FINAL PRESSURE: 1000 psig at 70 °F  
1113 psig at 130 °F  
DIMENSIONS: 9 in diameter 15 in length

Both components are flammable, so the mixture F code is 2 (as determined by the mixture producer).

Image

The mixture is a nonliquefied gas between 500 psig and 3000 psig, so the S code is 6 (as determined by the mixture producer).

Neither component is corrosive, so the mixture C code is 0 (as determined by the mixture producer).

MIXTURE FTSC: 2 2 6 0
MIXTURE LC50: 1000 ppm

STEPS ON ALGORITHM: (See Example 10)

  1. Mixture LC50 is > 200 ppm.
  2. Mixture LC50 is > 200 ppm, ≤ 5000 ppm, and the mixture contains a hazard zone A component.
  3. No PRD is required. If one is used, it shall be CG-4.
26

Example 10—2% arsine, balance hydrogen (U.S. customary units)

Example 10—2% arsine, balance hydrogen (U.S. customary units)

27

Worksheet for Example 11
0.2% arsine, balance hydrogen
(U.S. customary units)

  COMPONENTS CONCENTRATION F T S C LC50
1. Arsine 0.2% 2 3 0 0 20 ppm
2. Hydrogen Balance 2 1 6 0 > 5000 ppm

 

DOT CYLINDER RATING: 3AA2015  
FINAL PRESSURE: 1000 psig at 70°F  
1113 psig at 130 °F  
DIMENSIONS: 9 in diameter 15 in length

Both components are flammable, so the mixture F code is 2 (as determined by the mixture producer).

Image

The mixture is a nonliquefied gas between 500 psig and 3000 psig, so the mixture S code is 6 (as determined by the mixture producer).

Neither component is corrosive, so the mixture C code is 0 (as determined by the mixture producer).

MIXTURE FTSC: 2 1 6 0
MIXTURE LC50: 10 000 ppm

STEPS ON ALGORITHM: (See Example 11)

  1. Mixture LC50 > 200 ppm.
  2. Mixture LC50 is > 5000 ppm, and the mixture contains a hazard zone A component.
  3. No PRD is required. If one is used, it shall be a CG-4.
28

Example 11—0.2% arsine, balance hydrogen (U.S. customary units)

Example 11—0.2% arsine, balance hydrogen (U.S. customary units)

29

Worksheet for Example 12
5% arsine, 10% phosphine, balance hydrogen
(U.S. customary units)

  COMPONENTS CONCENTRATION F T S C LC50
1. Arsine 5% 2 3 0 0 20 ppm
2. Phosphine 10% 3 3 1 0 20 ppm
3. Hydrogen Balance 2 1 6 0 > 5000 ppm

 

DOT CYLINDER RATING: 3AA2015  
FINAL PRESSURE: 1000 psig at 70 °F  
1113 psig at 130 °F  
DIMENSIONS: 9 in diameter 15 in length

The mixture contains three flammable components, one of which is pyrophoric, so the mixture F code is 3 (as determined by the mixture producer).

Image

The mixture is a nonliquefied gas between 500 psig and 3000 psig, so the mixture S code is 6 (as determined by the mixture producer).

Neither component is corrosive, so the mixture C code is 0 (as determined by the mixture producer).

MIXTURE FTSC: 3 3 6 0
MIXTURE LC50: 133 ppm

STEPS ON ALGORITHM: (See Example 12)

  1. Mixture LC50 is < 200 ppm.
  2. PRD is prohibited.
30

Example 12—5% arsine, 10% phosphine, balance hydrogen (U.S. customary units)

Example 12—5% arsine, 10% phosphine, balance hydrogen (U.S. customary units)

31

6 References

Unless otherwise specified, the latest edition shall apply.

[1] Code of Federal Regulations, Title 49 (Transportation) Parts 100 to 180, Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402. www.gpoaccess.gov

[2] Transportation of Dangerous Goods Regulations, Transport Canada, Canadian Government Publishing, Public Works and Government Services Canada, Ottawa, ON K1A 0S9, Canada, www.tc.gc.ca

[3] CGA V-7, Standard Method of Determining Cylinder Valve Outlet Connections for Industrial Gas Mixtures, Compressed Gas Association, Inc., Compressed Gas Association, Inc., 4221 Walney Rd., 5th Floor, Chantilly, VA 20151. www.cganet.com

[4] CGA S-1.1, Pressure Relief Device Standards—Part 1—Cylinders for Compressed Gases, Compressed Gas Association, Inc., 4221 Walney Rd., 5th Floor, Chantilly, VA 20151. www.cganet.com

[5] CGA P-11, Metric Practice Guide for the Compressed Gas Industry, Compressed Gas Association, Inc., 4221 Walney Rd., 5th Floor, Chantilly, VA 20151. www.cganet.com

[6] CGA P-20, Standard for the Classification of Toxic Gas Mixtures, Compressed Gas Association, Inc., 4221 Walney Rd., 5th Floor, Chantilly, VA 20151. www.cganet.com

32

Appendix A—FTSC numerical code for gas classification (Normative)

 1st Digit — FIRE POTENTIAL
0       = inert
1       = supports combustion (oxidizing)
2       = flammable in air at 68 °F (20 °C) and 1 atm
3       = pyrophoric
4       = highly oxidizing
5       = may decompose or polymerize and is flammable
 2nd Digit — TOXICITY
  0     = life supporting (oxygen ≥ 19.5% in simple asphyxiant)
  1     = LC50 > 5000 ppm
  2     = 200 ppm < LC50 ≤ 5000 ppm
  3     = LC50 ≤ 200 ppm
 3rd Digit — STATE OF GAS: (in the cylinder at 70° F (21° C)1)
    0   = noncryogenic liquefied gas (less than 500 psi) (3450 kPa)2)—gas withdrawal
    1   = noncryogenic liquefied gas (over 500 psi) (3450 kPa)—gas withdrawal
    2   = liquefied gas (liquid withdrawal)3)
    3   = dissolved/absorbed gas
    4   = nonliquefied gas—or cryogenic gas withdrawal (less than 500 psi) (3450 kPa)
    5   = Europe only
    6   = nonliquefied gas between 500 psi and 3000 psi (3450 kPa and 20 680 kPa)
    7   = nonliquefied gas above 3001 psi and below 10 000 psi (20 690 kPa and 68 950 kPa)
    8   = cryogenic gas (liquid withdrawal) above –400 °F (–240°C)
    9   = cryogenic gas (liquid withdrawal) below –400 °F (–240°C)
 4th Digit — CORROSIVENESS:
      0 = noncorrosive
      1 = nonhalogen acid forming
      2 = basic
      3 = halogen acid forming
33

Appendix B—List of gases (Normative)

FTSC Code LC50 (ppm) Name of gas
* Not a compressed gas
5130      Acetylene
2200      Acrylonitrile
1060      Air
2100      Allene
       Allylene (See Methylacetylene)
2102 7 338    Ammonia, Anhydrous
0303 30    Antimony Pentafluoride
0160      Argon
0303 20    Arsenic Pentafluoride
2300 20    Arsine
       Boron Chloride (See Boron Trichloride)
       Boron Fluoride (See Boron Trifluoride)
0203 2 541 * Boron Trichloride
0263 806    Boron Trifluoride
4303 50 * Bromine Pentafluoride
4303 180 * Bromine Trifluoride
0203 260 * Bromoacetone
0100   * Bromochlorodifluoromethane (R12B1) or (Halon 1211)
0100   * Bromochloromethane (Halon 1011)
0100      Bromodifluoromethane (HBFC-22 B1)
       Bromoethylene (See Vinyl Bromide)
       Bromomethane (See Methyl Bromide)
3100      Bromotrifluoroethylene (R113B1)
0100      Bromotrifluoromethane (R13B1 or Halon 1301)
5100 220 000    1,3 Butadiene, (Inhibited)
2100      Butane, Normal
2100      1-Butene
2100      2-Butene
0110      Carbon Dioxide
2200      Carbon Disulfide
       Carbonic Acid (See Carbon Dioxide)
2260 3 760    Carbon Monoxide
       Carbon Oxysulfide (See Carbonyl Sulfide)
       Carbon Tetrafluoride (See Tetrafluoromethane)
       Carbonyl Chloride (See Phosgene)
0213 360    Carbonyl Fluoride
2201 1 700    Carbonyl Sulfide
4203 293    Chlorine
4303 122    Chlorine Pentafluoride
4203 299    Chlorine Trifluoride
2100      Chlorodifluoroethane (R142b)
0100      Chlorodifluoromethane (R22)
0100      Chlorodifluoromethane/Chloropentafluoroethane (Mixture) (R502)
       Chloroethane (See Ethyl Chloride)
       Chloroethylene(See Vinyl Chloride)
2100      Chlorofluoromethane (R31) 34
0100      Chloroheptafluorocyclobutane (RC317)
       Chloromethane(See Methyl Chloride)
0100      Chloropentafluoroethane (R115)
0100      1-Chloro-1,2,2,2-Tetrafluoroethane (R124)
0100      1-Chloro-2,2,2-Trifluoroethane (R133a)
5200 2 000    Chlorotrifluoroethylene (R1113)
0100      Chlorotrifluoromethane (R13)
2200 350    Cyanogen
0303 80    Cyanogen Chloride
2100      Cyclobutane
2100 220 000    Cyclopropane
2160      Deuterium
0213 3 120    Deuterium Chloride
0203 1 100 * Deuterium Fluoride
2301 2    Deuterium Selenide
2201 710    Deuterium Sulfide
5360 80    Diborane
0100 27 000 * Dibromodifluoromethane (R12B2) (Halon 1202)
       Dibromomethane (See Methylene Bromide)
0100   * 1,2 Dibromotetrafluoroethane (R114B2) (Halon 2402)
0100   * 1,2 Dichlorodifluoroethylene (R1112a)
0100      Dichlorodifluoromethane (R12)
0100      Dichlorodifluoromethane/Difluoroethane Mixture (R500)
0200   * 1,2 Dichloroethylene (R1130)
0100   * Dichlorofluoroemethane (R21)
0100   * 1,2 Dichlorohexafluorocyclobutane (RC316)
2100      Dichloromethane
2203 314 * Dichlorosilane
0100   * 1,1 Dichlorotetrafluoroethane (R114a)
0100   * Dichlorotetrafluoroethane (R114)
0100   * 2,2 Dichloro-1,1,1-Trifluoroethane (R123)
       Dicyan (See Cyanogen)
3300 10 * Diethylzinc
2100      1,1 Difluoroethane (R152a)
2110      1,1 Difluoroethylene (R1132a)
       Difluoromethane (See Methylene Fluoride)
2102   * Dimethylamine, Anhydrous
       Dimethyl Disulfide (See Methyl Disulfide)
2100      Dimethyl Ether
2100 > 5 000 * Dimethylsilane
       Dimethyl Sulfide (See Methyl Sulfide)
2100   * 2,2 Dimethylpropane
0303 2    Diphosgene
2110      Ethane
       Ethanethiol (See Ethyl Mercaptan)
2100   * Ethylacetylene
2100   * Ethyl Chloride
0303 36    Ethyldichloroarsine 35
2160      Ethylene
5200 2 920 * Ethylene Oxide
2100   * Ethyl Ether
2100      Ethyl Fluoride
2100      Ethyl Mercaptan
4343 185    Fluorine
       Fluoroform (R23) (See Trifluoromethane)
2200 622    Germane
0203      Germanium Tetrachloride
0160      Helium
       Helium/Oxygen Mixture
2300 10    Heptafluorobutyronitrile
0100      Heptafluoropropane (HFC-227 ea)
0203 470    Hexafluoroacetone
2100 > 5 000    Hexafluorocyclobutene
0100      Hexafluoroethane (R116)
0100      Hexafluoropropylene (R1216)
2160      Hydrogen
0203 2 860    Hydrogen Bromide
0213 3 120    Hydrogen Chloride
5301 140    Hydrogen Cyanide
0203 1 276 * Hydrogen Fluoride
0203 2 860    Hydrogen Iodide
2301 2    Hydrogen Selenide
2201 712    Hydrogen Sulfide
4303 120 * Iodine Pentafluoride
0203      Iodomethane
2100      Isobutane
2100      Isobutylene
0160      Krypton
0303      Lewisite (Dichloro 2-Chloro Vinyl Arsine)
2160      Methane
2100      Methylacetylene
0200 850 * Methyl Bromide
2100   * 3-Methyl-1-Butene
2100 8 300    Methyl Chloride
0303      Methyldichloroarsine
2300      Methyl Disulfide
2203   * Methylene Bromide
2110      Methyl Fluoride (R41)
2110      Methylene Fluoride (R32)
2100   * Methyl Formate
0303   * Methyl Iodide
2201 1 350    Methyl Mercaptan
2100 >5 000    Methylsilane
2100      Methyl Sulfide
2102   * Monoethylamine
2102      Monomethylamine, Anhydrous 36
0303 4    Mustard Gas
2160      Natural Gas
0160      Neon
2300 20 * Nickel Carbonyl
4361 115    Nitric Oxide
0160      Nitrogen
4301 115 * Nitrogen Dioxide
4301   * Nitrogen Tetroxide
4160 6 700    Nitrogen Trifluoride
4301 115    Nitrogen Trioxide
0303 35    Nitrosyl Chloride
0303      Nitrosyl Fluoride
4110      Nitrous Oxide
0303      Nitryl Fluoride
0100      Octafluorocyclobutane (RC318)
0200      * Octafluorocyclopentene (C5F8)
0100      Octafluoropropane (R218)
4060      Oxygen
4343 2.6    Oxygen Difluoride
4330 9    Ozone (Dissolved in R13)
3300 10 * Pentaborane
0100      Pentafluoroethane (HFC-125)
2300 10    Pentafluoropropionitrile
4203 770    Perchloryl Fluoride
2200      Perfluorobutadiene
0100   * Perfluorobutane (FC-3-1-10)
0100 12 000 * Perfluoro-2-Butene
0303 5    Phenylcarbylamine Chloride
0303 5    Phosgene
3310 20    Phosphine
0203 255    Phosphorous Pentafluoride
0203 425    Phosphorous Trifluoride
2100      Propane
2100      Propylene
3160 19 000    Silane
0203 750 * Silicon Tetrachloride
0263 450    Silicon Tetrafluoride
5300 20    Stibine
0201 2 520    Sulfur Dioxide
0100      Sulfur Hexafluoride
0303 40    Sulfur Tetrafluoride
0200 3 020    Sulfuryl Fluoride
0100      Tetrachloromethane
0100      1,1,1,2 Tetrafluoroethane (R-134a)
5100      Tetrafluoroethylene-lnhibited (R1114)
4340 100    Tetrafluorohydrazine
0160      Tetrafluoromethane (R-14)
2200   * Tetramethyllead 37
0100   * Trichlorofluoromethane (R11)
0100      Trichloroethylene
2203 1 040 * Trichlorosilane
0100   * 1,1,1 Trichlorotrifluoroethane (R113a)
0100   * 1,1,2 Trichlorotrifluoroethane (R113)
3300 10    Triethylaluminum
3200 1 400    Triethylborane
2200 500    Trifluoroacetonitrile
0203 208    Trifluoroacetylchloride
2100      1,1,1 Trifluoroethane (R143a)
0110      Trifluoromethane (HFC-23)
4363      Trifluoromethyl Hypofluorite
0200      Trifluoromethyl Iodide
2102 7 000 * Trimethylamine
2100 > 5 000 * Trimethylsilane
3300 20    Trimethylstibine
0203 213 * Tungsten Hexafluoride
0303   * Uranium Hexafluoride
5100 >5 000 * Vinyl Bromide
5100 >5 000    Vinyl Chloride
5100 >5 000    Vinyl Fluoride
5100 >5 000    Vinyl Methyl Ether
0160      Xenon
38

Appendix C—Sample worksheet (Informative)

  COMPONENTS CONCENTRATION F T S C LC50
1.              
2.              
3.              
4.              
5.              

 

DOT CYLINDER RATING:
FINAL PRESSURE psig @ 70 °F
psig @ 130 °F
CYLINDER DIMENSIONS:
MIXTURE FTSC:
MIXTURE LC50:
39 40