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Compressed gas emergency response containment vessels
Compressed Gas Emergency Response Containment Vessels Eugene Y. Ngai In the US major legislation has been passed affecting the way fugitive emission incidents are dealt with and is forcing companies to do more to implement quick and safe responses. For the compressed gases, the device which can fulfill many of these requirements are Emergency Response Containment Vessels (ERCV) from Solkatronic Chemicals Inc. This article describes the recent legislation and then outlines Solkatronic's specific response. S
ince the mid 1980s the US Regulatory Community has been trying to minimize the potential for public exposure to Hazardous Materials by regulating every phase of a substance's life cycle. These can be broadly defined as five distinct phases: Manufacturing, Storage, Transportation,
Use, Disposal. Since 1985 major legislation has been passed by Federal, State, and Local Government Agencies affecting the way fugitive emissions or Haz Mat incidents are dealt with and is forcing companies that handle, transport or store Hazardous Materials to do more preplanning and communicating with the public. Some of these include: OSHA - 29 CFR 1910.120 / 120 (Hazardous Waste Operations and Emergency Response Regulations). Training and preplanning requirements for Emergency Response Teams at RCRA and Hazardous Material facilities. HM - 126C (Emergency Response Communication Standards). US Department of Transportation regulation (effective December 31, 1990) for the shipment of all Hazardous Materials requires the inclusion of technical names, emergency response information on shipping papers, and 24 hour assistance telephone number. Other transportation regulations include HM-126F requiring training of all employees preparing a shipment of Hazardous Materials. SARA Title III (Emergency Planning and Community Right to Know). US EPA regulation requiring the development of site specific Emergency Response Plans for all facilities handling greater than the threshold levels of 403 Hazardous Materials. To be developed with the LEPC and local First Responders. Part 311 of the regulations also details ER training similar to OSHA. NJ Toxic Catastrophe Prevention Act. A
1988 NJ
regulation requiring manufacturers, storers or users that handle greater than the threshold quantity of 104 EHS (Extremely Hazardous Substances) to prepare a written Risk Analysis on all phases of an operation involving the substance. This Risk Management Plan (RMP) is reviewed by a consultant to insure that there is minimal risk to the public. The initial EHS list has been expanded to an additional 200 + substances. OSHA Process Safety Management. A 1992 U.S. regulation requiring a risk assessment similar to NJTCPA for facilities handling above the threshold amount
Solkatronic E R C V in action
for 137 highly hazardous chemicals and for any flammable liquid or gas in quantities of 10,000 pounds or more (excluding those used as fuel). Uniform Fire Code Article 80. A model Fire Code by the Western Fire Chiefs Association detailing the facility requirements for use and storage of Hazardous Materials above the exempt amounts. Requirements include: detection, containment and/or scrubbing of a worse-case leak for largest container. Hazardous Materials Management Plan (HMMP) and Hazardous Material Inventory Statement (HMIS) may also be required. Santa Clara County Toxic Gas Ordinance. Originally, California Assembly Bill 1021, which was adopted by all the communities in Santa Clara County California in 1989. Primary focus is on compressed gases and places additional requirements to Article 80 in the storage and use of gases based on their MHI (Material Hazard Index) values. Of these, the last two are attempts by the Fire Community to regulate the manufacturing, storage, and use of Hazardous Materials. In almost all communities
i
'
f
{ IZ
, 7, :
i •
Highly ~,,,~i~ {)xidizcr. (ol-ro>i\,..
Asphyxia**~ ('arcinogemt Radioactive. With m a n y hax, illg tin,re than one of these hazards. With the exception of Oxidizer ~tnd Radioactive, the ERCVs by Solkatronic Chemicals Inc. can be used to safely con,am all of these. Once contained in the ERCVs, the t,iS DOT Exemptions g10323 for Model #5501 and #105t)4 for Model #5502 allow these to be sent back to the gas supplier or to a disposal c~mlpany via a contracted carrier o r compan} Iruck f~,!-c~m~rolled leak mitigation throughout the USA the FiTc l)epartmcp~i:. ,~cla;~i~. have become the first responders 1~ : ~ , ii~t/ \'l.~i incident. The task they are faced with i>, ¢,vc~\~hcltnm&4.. when one considers the 10,000 ~,r more chetnic;l{,, ihal .it,.? m routine use. Article 80, which was finalized in 1987 by the Western Fire Chiefs Association after t~o years of dedicated effort by Fire Department representatives and consuhants, was the first major attempt to give local communities ;~ mechanism to control the handling and t, se of all Hazardous Materials. For many Western states, this became effective in 1988 when they' adopted the 1988 Uniform Fire Codes. All of the other model code associations in the USA followed suit with their version of a Hazardous Materials (;ode using Article 80 as a template. l-he Southern Building Code Congress International in July It), 1990, adopted their version as Chapter 22 m the Standard Fire Prevention Code. The Building Officials and Code A d m i n i s t r a t o r s International Inc. ( B O C A ) i n 1992 adopted it as Article 23 in September, lt)92
Response What is common to all of these is the need to develop a quick and sate response to Hazardous Material incidem~ that
ca.n
occuli
On Site, In Transportation, In Storage, At Customer Site. One device cannot offer the universal cure to all Haz Mat problems. An effective ER Team will have a wide variety ot" devices on hand to use, depending on the immediate situation. For the compressed gases, the device which can fulfill many of these requirements are Emergency Response Containment Vessels (ERCV) from Solkatronic Chemicals Inc. These are ASME Section VIII Division 1 coded vessels which are DOT approved for transportation while containing a leaking gas cylinder. Well over a 200 different gases and liquids are packaged in compressed gas cylinders. In addition, many of these are also mixed together in various concentrations to suit a particular process or need. Besides presenting a pressure hazard, the cylinders contain substances which can be: Flammable. Pyrophoric.
IIiiiiii
Two sizes T,ao sizes are offered, Model 5501 for cylinders smaller than 17 liters (8" dia x 30" with cap) and Model 5502 for cylinders smaller than 50 liters (11: dia x (~" with cap). Both have been designed to safely contain the sudden release of pressure from these cylinders. Model 55(/I has a working pressure of 1480 psig while Model 55(12 has a working pressure of I100 ps,g. Model 5501 has an internal volume ol ~0.24 liters. If ,~ leaking 16-liter cylinder with a 2100 psig mixture ~s inserted, the theoretical equilibrium pressure would be 1104 psig. The dead volume taken up by the cylinder positioners and cylinder steel will add another t0~!~, increasing this to 1216 psig. For Model 5502, which has an internal volume of 131.4 liters, a 2100 psig mixture m a 40 liter cylinder will have a theoretical equilibrium pressure of 774 psig and an adjusted pressure of 853 psig One of the basic tenets in ER incident preplanning is the ability to rapidly bring a situation under control in a sati: manner. The ERCVs offer that capability by being use, friendly. They were designed by the Solkatronic Chemicals Inc. Emergency Response Team to be used with a minimum of problems. A trained two-man ER Team can load either ERCV (#5501 or #5502) with a cylinder, close the flange, and start the purge gas in a matter of minutes. even suited up m Level "A" protection. Fhe vessels are highly mobile and can easily be moved to the desired location by 2 people wearing the appropriate PPE (Personal Protective Equipment). To minimize field adjustlnents, the flange seat was designed to hold two "O" Rings (Viton and Buna N) so that one is compatible with the product to be contained. Purge valves on both ends allow for quick and efficient purging in the field. For safe*', reasons, the Model #5502 cart also has 'normally on' disc brakes.
Emergency scrubber For the toxic and highly toxic compressed gases, U FC Article 80 requires the installation of an Emergency Scrubber that is capable of handling the catastrophic leak of the contents of the largest cylinder m these areas used or stored and exhaust it at I 2 I D L H to theatmosphere. ]'he scrubber, gas detection and ventilation systems must bc tied into standby or emergency p o w e r This applies to all facilities that handle and/or store above the exempt amounts of the gases.
iiiiiiiiill
Risk analysis On the surface, these requirements appear to be realistic and will be of great value in minimizing public exposure to Haz Mat leaks. A risk analysis would reveal, however, that the requirements are justified only for manufacturing and use. These are the only times that the cylinder valve will be open, the cylinder cap removed and the vapor tight cap/ plug removed. In this position, the valve is wide open and failure of any one of the many pipe connections or components in a piping system from the cylinder to the process could release significant quantities of gas. Statistically, the odds of a leak happening is increased with the addition of more fittings or components. Article 80 attempts to minimize the probability and impact of these events by requiring: Ventilated Enclosures, Welded or other Approved Connections, Coaxial Tubing for long runs, Emergency Shut-off Valves, Gas Detection, Gas Treatment Systems.
Leaks An informal review of gas industry data on leaks support the conclusion that leaks, if they are to occur, happen primarily in manufacturing and use. The remaining incidents are almost all transportation incidents in which cylinders have been violently tossed around because they were not properly secured or from vehicular accidents or fires. For many gas storage facilities at user and supplier sites, the requirements for emergency scrubbing and power is overkill for the potential risk. Of all the incidents, gas storage accounts for < 1%. and these are generally small in nature. The catastrophic failure envisioned by Article 80 is an unlikely event without a severe external event such as a fire or explosion. In either of these events, the scrubber would be rendered useless. The Washington State Article 80 study group in 1989 also viewed the requirements to be costly and impractical. For small storage facilities (typical electronic fab), the scrubbing system will become very complex if a variety of gases are stored. If only one scrubber is used, it must be capable of rapidly distinguishing between: Alkaline Gases (NH3), Acid Gases (HC1, C12),
Basic Building
Approximate areas of code influence
Hydride Gases (ASH3, PH3), Pyrophoric Gases (Sill4, B2Ho), Oxidizing Gases (NO, NO2). because they require different scrubbing solutions and/or methods. It then must switch on the appropriate devices in a matter of seconds. If separate scrubbers are used for each, the capital and maintenance cost will be a severe burden. More importantly, the installed systems can lead to a false sense of security since they may not work when it is needed since all of the systems will require routine testing and maintenance. A gas cylinder would have 3-4 potential leak points, all of which in storage would be of a very low flow rate since the cylinder valve is not open. In the absence of the external events described earlier, the potential leaks are as follows: • A leak through the vapor-tight cap or plug would require both the valve seat to be loose or damaged and the vapor-tight cap or plug to be loose. It is unlikely that both could become fully loosened for a large leak to occur with the cylinder cap on. • For a packed valve, a leak could occur at the stem but, again, this would also require the valve seat to be loose or damaged. • For valves with a pressure-relief device, a small leak could occur through the threads if it is damaged or not installed properly. • A thread leaker could develop at the valve threads into the cylinder. A large leak could only occur if the valve is damaged or not properly installed. It is unlikely that this would go undetected in the filling process. The more common event is a small leak ( < 10 cc/min.). All of these potential leaks would be detected immediately by the gas detection system required by the codes. The site ER Team would then use an ERCV to contain the leaking cylinder for shipment back to the supplier or disposal company for final leak mitigation procedures. If it is at a gas supplier site, this would buy valuable time in setting up controlled disposal. This would be more effective than having emergency scrubbers, cabinet and power in a storage area. Many of the Fire Codes are beginning to recognize this alternative. The State of Oregon, during the adoption of Article 80 in 1989, added the exception (80.303.(a) 6.D.iv): "Upon approval of the chief, it can be demonstrated that alternate means are capable of managing any release that would not create an immediate threat to life or property" which would allow the substitution of ERCVs for scrubbers. More specifically, the Southern Building Code Congress International in 1990 adopted the exception (408.4.2.7.2) to the Southern Building Code: "Cylinder containment device or system may be accepted in lieu of the treatment system, for cylinder storage, when approved by the Fire Official". The State of Washington in adopting Article 80 added the exception (80:303 (c) 3 B). "A cabinet or exhausted enclosure need not be provided for leaking cylinders if a US DOT approved cylinder containment vessel is provided." In 1990 the Uniform Fire Code Committee of the Western Fire Chiefs Association approved the following exception to Article 80:(80.803 (c) 3 Special Provisions):
[liiiiiHliiMiii ii i iiiHiiitl
<,] ~?
5'pecificaLions DOT E x e m p h o n
# [': 10504
>ff _. N<;,
(without cylinder) 34 6 gallons (1:31 4 liters} Volume
Weight ( e m p t y )
945
Ibs
Height (overall) 38" Width {overall) 28 Length (overall) 7 9 ' K~..L@e
~LEessure Vessel ASME S e c t i o n VIII Division Length (overall) 7 9 ( i n t e r n a l ) 74" D , a m e t e r ( o u t e r ) !2 7 5 ( i n n e r ) 11 "75' "fA 106 Grade C C a r b o n Steel Working P r e s s u r e 1100 psig H v d r o t e s t P r e s s u r e 1680 psig Operating Temp -2OF to 130F
F'i~ nge Double BoIL q u i c k O p e n i n g By Tube T u r n s ('a r bon Steel Chain and S p r o c k e t DrF,'e [)Hubie "O' Ring Seal [nyqde Viton Outside
Front
-
At
h
\,"le w
&G
"- . , t
-
. . . . . . . .
Bun~, N
~Ide
vlc w
Compressed gas emergency containment vessels
".., or approved containment vessels are provided that they are capable of fully containing a release". In the July, 1991 meeting of the Western Fire Chiefs Association, the following revision was approved for the 1991 Uniform Fire Code under 80.803 (c) 3 Special Provisions: E X C E P T I O N : A cabinet or exhausted enclosure need not be provided for leaking cylinders if all cylinders are stored within gas cabinets or exhausted enclosures, or if approved containment vessels capable of fully containing a release and trained personnel are available at an approved location. Such vessels shall be capable of being transported to the leaking cylinder locations. On March 27, 1991, the Santa Clara County Fire Chiefs Association Hazardous Materials Subcommittee adopted consensus guidelines for the Toxic Gas Ordinance for Section XI: Encapsulating equipment designed to contain high-pressure cylinders and their contents, as approved by the Fire Chief, shall be acceptable in meeting the intent of providing a gas cabinet or exhausted enclosure for leaking gas cylinders. At BOCA, the High Hazard Committee recommended the adoption of similar language in Article 23 Section F2303.3.8.1 Exception 2: A cabinet or exhausted enclosure is not required for leaking cylinders where all cylinders are stored within gas
cabinets or exhausted enclosures or where toxic gases are provided with: a. Approved containment devices that are capable of fully containing a release are available at an approved location on site. b. Trained personnel are available at an approved location on site, and c. Such containment devices are capable of being transported to the leaking cylinder. At the September, 1992, meeting, this was not approved: however, there were a number of challenges by members to adopt it. Areas of influence throughout the USA by the three model code associations are shown in the figure. The use of ERCVs is fast becoming recognized in the United States as being one of the important leak containment devices available for compressed gases. Eugene Y. Ngai, VP Corporate Development Health, SaJety and Environment, Solkatronic Chemicals lnc, 30 Two Bridges Rd., Fai(/}eht, NJ 07004-1530 USA. Telffhx: I l l (20])882 7900 / 7967.
ince the mid 1980s the US Regulatory Community has been trying to minimize the potential for public exposure to Hazardous Materials by regulating every phase of a substance's life cycle. These can be broadly defined as five distinct phases: Manufacturing, Storage, Transportation,
Use, Disposal. Since 1985 major legislation has been passed by Federal, State, and Local Government Agencies affecting the way fugitive emissions or Haz Mat incidents are dealt with and is forcing companies that handle, transport or store Hazardous Materials to do more preplanning and communicating with the public. Some of these include: OSHA - 29 CFR 1910.120 / 120 (Hazardous Waste Operations and Emergency Response Regulations). Training and preplanning requirements for Emergency Response Teams at RCRA and Hazardous Material facilities. HM - 126C (Emergency Response Communication Standards). US Department of Transportation regulation (effective December 31, 1990) for the shipment of all Hazardous Materials requires the inclusion of technical names, emergency response information on shipping papers, and 24 hour assistance telephone number. Other transportation regulations include HM-126F requiring training of all employees preparing a shipment of Hazardous Materials. SARA Title III (Emergency Planning and Community Right to Know). US EPA regulation requiring the development of site specific Emergency Response Plans for all facilities handling greater than the threshold levels of 403 Hazardous Materials. To be developed with the LEPC and local First Responders. Part 311 of the regulations also details ER training similar to OSHA. NJ Toxic Catastrophe Prevention Act. A
1988 NJ
regulation requiring manufacturers, storers or users that handle greater than the threshold quantity of 104 EHS (Extremely Hazardous Substances) to prepare a written Risk Analysis on all phases of an operation involving the substance. This Risk Management Plan (RMP) is reviewed by a consultant to insure that there is minimal risk to the public. The initial EHS list has been expanded to an additional 200 + substances. OSHA Process Safety Management. A 1992 U.S. regulation requiring a risk assessment similar to NJTCPA for facilities handling above the threshold amount
Solkatronic E R C V in action
for 137 highly hazardous chemicals and for any flammable liquid or gas in quantities of 10,000 pounds or more (excluding those used as fuel). Uniform Fire Code Article 80. A model Fire Code by the Western Fire Chiefs Association detailing the facility requirements for use and storage of Hazardous Materials above the exempt amounts. Requirements include: detection, containment and/or scrubbing of a worse-case leak for largest container. Hazardous Materials Management Plan (HMMP) and Hazardous Material Inventory Statement (HMIS) may also be required. Santa Clara County Toxic Gas Ordinance. Originally, California Assembly Bill 1021, which was adopted by all the communities in Santa Clara County California in 1989. Primary focus is on compressed gases and places additional requirements to Article 80 in the storage and use of gases based on their MHI (Material Hazard Index) values. Of these, the last two are attempts by the Fire Community to regulate the manufacturing, storage, and use of Hazardous Materials. In almost all communities
i
'
f
{ IZ
, 7, :
i •
Highly ~,,,~i~ {)xidizcr. (ol-ro>i\,..
Asphyxia**~ ('arcinogemt Radioactive. With m a n y hax, illg tin,re than one of these hazards. With the exception of Oxidizer ~tnd Radioactive, the ERCVs by Solkatronic Chemicals Inc. can be used to safely con,am all of these. Once contained in the ERCVs, the t,iS DOT Exemptions g10323 for Model #5501 and #105t)4 for Model #5502 allow these to be sent back to the gas supplier or to a disposal c~mlpany via a contracted carrier o r compan} Iruck f~,!-c~m~rolled leak mitigation throughout the USA the FiTc l)epartmcp~i:. ,~cla;~i~. have become the first responders 1~ : ~ , ii~t/ \'l.~i incident. The task they are faced with i>, ¢,vc~\~hcltnm&4.. when one considers the 10,000 ~,r more chetnic;l{,, ihal .it,.? m routine use. Article 80, which was finalized in 1987 by the Western Fire Chiefs Association after t~o years of dedicated effort by Fire Department representatives and consuhants, was the first major attempt to give local communities ;~ mechanism to control the handling and t, se of all Hazardous Materials. For many Western states, this became effective in 1988 when they' adopted the 1988 Uniform Fire Codes. All of the other model code associations in the USA followed suit with their version of a Hazardous Materials (;ode using Article 80 as a template. l-he Southern Building Code Congress International in July It), 1990, adopted their version as Chapter 22 m the Standard Fire Prevention Code. The Building Officials and Code A d m i n i s t r a t o r s International Inc. ( B O C A ) i n 1992 adopted it as Article 23 in September, lt)92
Response What is common to all of these is the need to develop a quick and sate response to Hazardous Material incidem~ that
ca.n
occuli
On Site, In Transportation, In Storage, At Customer Site. One device cannot offer the universal cure to all Haz Mat problems. An effective ER Team will have a wide variety ot" devices on hand to use, depending on the immediate situation. For the compressed gases, the device which can fulfill many of these requirements are Emergency Response Containment Vessels (ERCV) from Solkatronic Chemicals Inc. These are ASME Section VIII Division 1 coded vessels which are DOT approved for transportation while containing a leaking gas cylinder. Well over a 200 different gases and liquids are packaged in compressed gas cylinders. In addition, many of these are also mixed together in various concentrations to suit a particular process or need. Besides presenting a pressure hazard, the cylinders contain substances which can be: Flammable. Pyrophoric.
IIiiiiii
Two sizes T,ao sizes are offered, Model 5501 for cylinders smaller than 17 liters (8" dia x 30" with cap) and Model 5502 for cylinders smaller than 50 liters (11: dia x (~" with cap). Both have been designed to safely contain the sudden release of pressure from these cylinders. Model 55(/I has a working pressure of 1480 psig while Model 55(12 has a working pressure of I100 ps,g. Model 5501 has an internal volume ol ~0.24 liters. If ,~ leaking 16-liter cylinder with a 2100 psig mixture ~s inserted, the theoretical equilibrium pressure would be 1104 psig. The dead volume taken up by the cylinder positioners and cylinder steel will add another t0~!~, increasing this to 1216 psig. For Model 5502, which has an internal volume of 131.4 liters, a 2100 psig mixture m a 40 liter cylinder will have a theoretical equilibrium pressure of 774 psig and an adjusted pressure of 853 psig One of the basic tenets in ER incident preplanning is the ability to rapidly bring a situation under control in a sati: manner. The ERCVs offer that capability by being use, friendly. They were designed by the Solkatronic Chemicals Inc. Emergency Response Team to be used with a minimum of problems. A trained two-man ER Team can load either ERCV (#5501 or #5502) with a cylinder, close the flange, and start the purge gas in a matter of minutes. even suited up m Level "A" protection. Fhe vessels are highly mobile and can easily be moved to the desired location by 2 people wearing the appropriate PPE (Personal Protective Equipment). To minimize field adjustlnents, the flange seat was designed to hold two "O" Rings (Viton and Buna N) so that one is compatible with the product to be contained. Purge valves on both ends allow for quick and efficient purging in the field. For safe*', reasons, the Model #5502 cart also has 'normally on' disc brakes.
Emergency scrubber For the toxic and highly toxic compressed gases, U FC Article 80 requires the installation of an Emergency Scrubber that is capable of handling the catastrophic leak of the contents of the largest cylinder m these areas used or stored and exhaust it at I 2 I D L H to theatmosphere. ]'he scrubber, gas detection and ventilation systems must bc tied into standby or emergency p o w e r This applies to all facilities that handle and/or store above the exempt amounts of the gases.
iiiiiiiiill
Risk analysis On the surface, these requirements appear to be realistic and will be of great value in minimizing public exposure to Haz Mat leaks. A risk analysis would reveal, however, that the requirements are justified only for manufacturing and use. These are the only times that the cylinder valve will be open, the cylinder cap removed and the vapor tight cap/ plug removed. In this position, the valve is wide open and failure of any one of the many pipe connections or components in a piping system from the cylinder to the process could release significant quantities of gas. Statistically, the odds of a leak happening is increased with the addition of more fittings or components. Article 80 attempts to minimize the probability and impact of these events by requiring: Ventilated Enclosures, Welded or other Approved Connections, Coaxial Tubing for long runs, Emergency Shut-off Valves, Gas Detection, Gas Treatment Systems.
Leaks An informal review of gas industry data on leaks support the conclusion that leaks, if they are to occur, happen primarily in manufacturing and use. The remaining incidents are almost all transportation incidents in which cylinders have been violently tossed around because they were not properly secured or from vehicular accidents or fires. For many gas storage facilities at user and supplier sites, the requirements for emergency scrubbing and power is overkill for the potential risk. Of all the incidents, gas storage accounts for < 1%. and these are generally small in nature. The catastrophic failure envisioned by Article 80 is an unlikely event without a severe external event such as a fire or explosion. In either of these events, the scrubber would be rendered useless. The Washington State Article 80 study group in 1989 also viewed the requirements to be costly and impractical. For small storage facilities (typical electronic fab), the scrubbing system will become very complex if a variety of gases are stored. If only one scrubber is used, it must be capable of rapidly distinguishing between: Alkaline Gases (NH3), Acid Gases (HC1, C12),
Basic Building
Approximate areas of code influence
Hydride Gases (ASH3, PH3), Pyrophoric Gases (Sill4, B2Ho), Oxidizing Gases (NO, NO2). because they require different scrubbing solutions and/or methods. It then must switch on the appropriate devices in a matter of seconds. If separate scrubbers are used for each, the capital and maintenance cost will be a severe burden. More importantly, the installed systems can lead to a false sense of security since they may not work when it is needed since all of the systems will require routine testing and maintenance. A gas cylinder would have 3-4 potential leak points, all of which in storage would be of a very low flow rate since the cylinder valve is not open. In the absence of the external events described earlier, the potential leaks are as follows: • A leak through the vapor-tight cap or plug would require both the valve seat to be loose or damaged and the vapor-tight cap or plug to be loose. It is unlikely that both could become fully loosened for a large leak to occur with the cylinder cap on. • For a packed valve, a leak could occur at the stem but, again, this would also require the valve seat to be loose or damaged. • For valves with a pressure-relief device, a small leak could occur through the threads if it is damaged or not installed properly. • A thread leaker could develop at the valve threads into the cylinder. A large leak could only occur if the valve is damaged or not properly installed. It is unlikely that this would go undetected in the filling process. The more common event is a small leak ( < 10 cc/min.). All of these potential leaks would be detected immediately by the gas detection system required by the codes. The site ER Team would then use an ERCV to contain the leaking cylinder for shipment back to the supplier or disposal company for final leak mitigation procedures. If it is at a gas supplier site, this would buy valuable time in setting up controlled disposal. This would be more effective than having emergency scrubbers, cabinet and power in a storage area. Many of the Fire Codes are beginning to recognize this alternative. The State of Oregon, during the adoption of Article 80 in 1989, added the exception (80.303.(a) 6.D.iv): "Upon approval of the chief, it can be demonstrated that alternate means are capable of managing any release that would not create an immediate threat to life or property" which would allow the substitution of ERCVs for scrubbers. More specifically, the Southern Building Code Congress International in 1990 adopted the exception (408.4.2.7.2) to the Southern Building Code: "Cylinder containment device or system may be accepted in lieu of the treatment system, for cylinder storage, when approved by the Fire Official". The State of Washington in adopting Article 80 added the exception (80:303 (c) 3 B). "A cabinet or exhausted enclosure need not be provided for leaking cylinders if a US DOT approved cylinder containment vessel is provided." In 1990 the Uniform Fire Code Committee of the Western Fire Chiefs Association approved the following exception to Article 80:(80.803 (c) 3 Special Provisions):
[liiiiiHliiMiii ii i iiiHiiitl
<,] ~?
5'pecificaLions DOT E x e m p h o n
# [': 10504
>ff _. N<;,
(without cylinder) 34 6 gallons (1:31 4 liters} Volume
Weight ( e m p t y )
945
Ibs
Height (overall) 38" Width {overall) 28 Length (overall) 7 9 ' K~..L@e
~LEessure Vessel ASME S e c t i o n VIII Division Length (overall) 7 9 ( i n t e r n a l ) 74" D , a m e t e r ( o u t e r ) !2 7 5 ( i n n e r ) 11 "75' "fA 106 Grade C C a r b o n Steel Working P r e s s u r e 1100 psig H v d r o t e s t P r e s s u r e 1680 psig Operating Temp -2OF to 130F
F'i~ nge Double BoIL q u i c k O p e n i n g By Tube T u r n s ('a r bon Steel Chain and S p r o c k e t DrF,'e [)Hubie "O' Ring Seal [nyqde Viton Outside
Front
-
At
h
\,"le w
&G
"- . , t
-
. . . . . . . .
Bun~, N
~Ide
vlc w
Compressed gas emergency containment vessels
".., or approved containment vessels are provided that they are capable of fully containing a release". In the July, 1991 meeting of the Western Fire Chiefs Association, the following revision was approved for the 1991 Uniform Fire Code under 80.803 (c) 3 Special Provisions: E X C E P T I O N : A cabinet or exhausted enclosure need not be provided for leaking cylinders if all cylinders are stored within gas cabinets or exhausted enclosures, or if approved containment vessels capable of fully containing a release and trained personnel are available at an approved location. Such vessels shall be capable of being transported to the leaking cylinder locations. On March 27, 1991, the Santa Clara County Fire Chiefs Association Hazardous Materials Subcommittee adopted consensus guidelines for the Toxic Gas Ordinance for Section XI: Encapsulating equipment designed to contain high-pressure cylinders and their contents, as approved by the Fire Chief, shall be acceptable in meeting the intent of providing a gas cabinet or exhausted enclosure for leaking gas cylinders. At BOCA, the High Hazard Committee recommended the adoption of similar language in Article 23 Section F2303.3.8.1 Exception 2: A cabinet or exhausted enclosure is not required for leaking cylinders where all cylinders are stored within gas
cabinets or exhausted enclosures or where toxic gases are provided with: a. Approved containment devices that are capable of fully containing a release are available at an approved location on site. b. Trained personnel are available at an approved location on site, and c. Such containment devices are capable of being transported to the leaking cylinder. At the September, 1992, meeting, this was not approved: however, there were a number of challenges by members to adopt it. Areas of influence throughout the USA by the three model code associations are shown in the figure. The use of ERCVs is fast becoming recognized in the United States as being one of the important leak containment devices available for compressed gases. Eugene Y. Ngai, VP Corporate Development Health, SaJety and Environment, Solkatronic Chemicals lnc, 30 Two Bridges Rd., Fai(/}eht, NJ 07004-1530 USA. Telffhx: I l l (20])882 7900 / 7967.