Provision of Carbon Dioxide Gas Suppression System in an Explosive Storage Facility

[uzbarry]

As'salam'u Alikum,

Can someone give technical suggestions/arguments, on the provision of "Carbon Dioxide Gas Suppression System" for an Explosive Facility with Torpoedo's and Warheads in it?? Will the System Prove to work ???

What I think, Gas suppression system is essentially a “one-shot” fire protection system. The system can only be used to suppress a fire "once" within a short period of time. The gas suppressing agent cylinders will have to be replaced before the system can be considered back on-line or we have to provide same Capacity Duty Cylinders (doubling the agent costs).

This means that, if the source isn't removed, the fault that caused the fire in the first place could again cause another fire to be ignited. When this occurs, the gas suppression system will not be able to be activated since a replacement cylinder will take a while to be replaced unless duty cylinders are provided!

What protection system can be installed other than the Gas Suppression System???

Wishing all of you a very blessed EID'ul Fitar!
Best Regards,


P.S. Please remember the Pakistan Flood Victims in your EID and Prayers Search youtube for the destruction the flood has certainly caused!

[uzbarry]

adding more to above:
the room dimensions area:

Length = 212 ft
Width = 80 ft
Height = 28 ft

[f81aa]

Hi uzbarry:

I find your post interesting because your concern is to protect military explosives, definetely not related to the Oil Industry. Not very often (I believe) most of us have to design protection for this type of materials.

I will take for granted that the requirements established by the Pakistan Government and local laws, Pakistan military and the weapons manufacturer have been strictly followed. In addition, there are other organizations that have published information regarding to the protection of explosives. One of them, the NFPA, has published the Explosive Materials Code (NFPA 495). To provide proper storage for the wide variety of explosive materials now being produced, different types of magazines are recognized. The probability of unintentional initiation of an explosive while in an approved storage location is very small.

I understand from your post that it has been proposed to protect with CO2 the enclosure were weapons will be stored. It is not clear to me if this is your decision (or somebody else) or if it is mandatory. This is very important because while browsing my copy of NFPA 495 Explosive Materials Code, 2001 edition, I found that its clause 4.1.1 states "No attempt shall be made to fight a fire that cannot be contained or controlled before it reaches explosive materials. In such cases, all personnel shall be evacuated immediately to a safe location, and the area shall be guarded from entry by spectators or intruders." I found no reference to any specific fixed fire protection system. So I would venture to say that the total flooding CO2 fixed fire protection system might not prove to work. And that no other fixed fire protection system should be installed.

It is important to keep in mind that fire is a principal cause of accidents involving explosive materials. Although explosives may vary in their sensitivity to fire conditions, there is always the potential to produce a disastrous explosion when subjected to fire. The only effective method for fire protection with explosive materials is to eliminate the source of fire. This involves meticulous housekeeping standards. It is often a small fire in oily rags or wastepaper that triggers a major catastrophe. Smoking or the use of any fire-producing equipment should not be permitted where explosive materials are produced, handled, stored, or used.

Now some comments on the "extra" CO2 needed for replacement.

CO2 as a fire suppression system is essentially a “one-shot” fire protection system. --> However, if reserve supplies are provided, it could be said that it is a “two-shot” fire protection system.

The system can only be used to suppress a fire "once" within a short period of time. --> Well, different people may have distint estimates for a short period of time. For certain type of fires (e.g. deep-seated fires), a properly designed total flooding system will have to extinguish the fire during at least 20 minutes by reducing drastically the O2 concentration and keeping it below certain values.

The gas suppressing agent cylinders will have to be replaced before the system can be considered back on-line or it has to be provided same Capacity Duty Cylinders (doubling the agent cost). --> According to NFPA 12 "Carbon Dioxide Extinguishing Systems", 2008 edition, clause 4.6.1.3 "Both main and reserve supplies for fixed storage systems shall be permanently connected to the piping and arranged for easy changeover, except where the authority having jurisdiction permits an unconnected reserve." Now, if one has to have both main and reserve supplies, why not to have them permanently connected to the distribution piping? The only justification that comes to my mind in this moment has to do with lack of space for both main and reserve supplies.

If the source isn't removed, the fault that caused the fire in the first place could again cause another fire to be ignited. When this occurs, the gas suppression system will not be able to be activated since a replacement cylinder will take a while to be replaced unless duty cylinders are provided! --> We now know reserve supplies have to be provided and permanently connected to the distribution piping.

I do not want to miss that phrase "doubling the agent cost". Sometimes a designer, using good engineering judgement, feels compelled to include "extra features" in order to provide an adequate protection. I would agree that one may question their value and benefits. On the other hand, knowing that NFPA 12 contains minimum requirements, I can not see the point of "doubling the agent cost" by following the minimum requirement of providing reserve supplies. The "extra cost" is part of the minimum design and it should be included in the cost estimation. As an analogy, to me it is just like asking to reduce the required thickness of a pressure vessel to reduce costs.

I hope that these comments will be useful to you and others. I would like to see other forum members sharing their comments.

Regards

[uzbarry]

Dear f81aa,
My apologies - for getting you back a bit late!

Well thank you so much for the detailed and REFERENCING reply! Indeed it will be useful for all the forum members!

I read the NFPA 495 before putting this question to the forum members and I'll putting some comments on your answers cum suggestions by Thursday Morning Inshallah!

thank you once again!

Regards,

[uzbarry]

Dear f81aa,
apologies - I was not able to post the answer on the said date and so far, I'm still not able to put a detail reply!

Well NFPA 425 does allow you to install "fixed fire protection system" for low primer storage facilities.
NFPA 69, does allow you to install gas protection systems for explosive facilities!

best regards,

[uzbarry]

Dear f81aa,
apologies - I was not able to post the answer on the said date and so far, I'm still not able to put a detail reply!

Well NFPA 495 does allow you to install "fixed fire protection system" for low primer storage facilities.
NFPA 69, does allow you to install gas protection systems for explosive facilities!

best regards,

Sorry it's NFPA 495

[DM2]

Besides the suppression, you need to consider the detection. A suppression system for such a hazard is likely useless after the first munitions have been spent as this would likely breach the enclosed space. With these types of hazards, I would think that the speed at which the hazard becomes untenable would be of paramount concern. There are detection systems designed specifically for these hazards. There are also fire sprinkler systems designed for these hazards but admittedly I'm not familiar with them only to say I'm aware of them. The design of the deluge valve is such that water is intended to be available at the sprinkler heads in seconds if not less.

[f81aa]

Hi:

My comments to respond to your posts # 5 and 6 are based on NFPA 495 Explosive Materials Code (2001 edition) and NFPA 69 Standard on Explosion Prevention Systems (2002 Edition). More recent editions could prove me wrong.

Consulting the above mentioned documents, I will try to explain why I believe the sprinkler and/or gas protection systems are not acceptable means of protection for torpedoes and warheads.

First of all, NFPA 495 shall apply to the manufacture, transportation, storage, sale, and use of explosive materials.

Two definitions to know are:

Explosive is any chemical compound, mixture, or device, the primary or common purpose of which is to function by explosion.

Explosive material is any explosive, blasting agent, emulsion explosive, water gel, or detonator.

I searched NFPA 495 for “fixed”, “fire”, “protection” and “system”. I found nothing related to fixed fire protection systems. Then I tried “sprinkler” and found out that quantities of commercial stocks of smokeless propellants exceeding 363 kg (800 lb), but not exceeding 2268 kg (5000 lb), shall be permitted to be stored in a building that shall be protected by an automatic sprinkler system. There are 7 additional requirements to comply with (clause 13.3.9).

Smokeless propellants are solid propellants, commonly referred to as smokeless powders, used in small arms ammunition, cannons, rockets, or propellant-actuated devices. A propellant is an explosive that normally functions by DEFLAGRATION and is used for propulsion purposes. And from WIKIPEDIA, warhead refers to the explosive material and detonator that is delivered by a missile, rocket, or torpedo.

Propellant is a part of the torpedo, not the whole thing. I do not see torpedoes and warheads related to clause 13.3.9.

There is also a requirement of providing an automatic sprinkler system in a building where small arms primers are stored in quantities exceeding 750,000. Again, there are 7 additional requirements to comply with (clause 13.5.6). Once more, torpedoes and warheads are not related to clause 13.5.6.

Generally speaking, the greatest threat to unintentional initiation of explosives is fire. Every effort should be made to prevent the start of fire near explosives. The only effective method for fire protection with explosive materials is to eliminate the source of fire. This involves meticulous housekeeping standards as well as design and installation standards.

Clause 4.1.1 states "No attempt shall be made to fight a fire that cannot be contained or controlled before it reaches explosive materials. In such cases, all personnel shall be evacuated immediately to a safe location, and the area shall be guarded from entry by spectators or intruders.”

One way to categorize various types of explosions is in terms of the energy source. We are familiar with combustion energy sources that cause gas explosions and dust explosions when the fuel and air are premixed and confined before being ignited. Other energy sources that can be released or transformed rapidly enough to produce explosions include condensed phase explosives, chemical reactions other than combustion, nuclear energy, potential energy due to compression, and extremely rapid vaporization.

Commercial and military condensed phase explosives are usually divided into two categories: high explosives and low explosives. High explosives, mainly used by the military, tend to DETONATE, having high shattering power.

NFPA 69 shall cover the minimum requirements for installing systems for the prevention of explosions in enclosures that contain flammable concentrations of flammable gases, vapors, mists, dusts, or hybrid mixtures. We know that they are combustion energy sources.

NFPA 69 shall apply to systems and equipment used for the prevention of explosions by the prevention or control of DEFLAGRATIONS.

NFPA 69 cites eleven cases where the standard is not applicable. I would like to point out these:
• Devices or systems designed to protect against detonations
• Protection against overpressure due to phenomena other than internal deflagrations
• Chemical reactions other than combustion processes
• General use of inert gas for fire extinguishment

I do not see torpedoes and warheads under the application of NFPA 69.

The methods recognized in this standard for explosion prevention are:
• Methods Based on the Prevention of Combustion
• Methods Based on the Prevention or Limitation of Damage

The standard contains six chapters, each one for a specific technique for explosion prevention. Those techniques are classified as DEFLAGRATION prevention or DEFLAGRATION control.

After reading the Section Application of any of those chapters, the reader will be convinced that the particular technique is not applicable for the protection of explosives.

In relation to the comment “NFPA 69, does allow you to install gas protection systems for explosive facilities!”, NFPA 69 certainly allows the installation of gas protection systems for the prevention of explosions in cases where the standard is applicable. That is, in enclosures containing flammable concentrations of flammable gases, vapors, mists, dusts, or hybrid mixtures. However, that these flammable concentrations can explode does not mean that the facility is an explosive facility or that explosive materials are covered by the standard.

The technique for oxidant concentration reduction for deflagration prevention shall be permitted to be considered where a mixture of oxidant and flammable material is confined to an enclosure within which the oxidant concentration can be controlled.

The system shall be maintained at an oxidant concentration that is low enough to prevent a deflagration.

Oxidant concentration reduction shall be permitted to be applied to rooms or buildings, but one of the following shall apply, since oxygen-deficient atmospheres cannot sustain life:
(1) Operations in such areas shall be remotely controlled.
(2) Operating personnel shall be provided with breathing apparatus, as well as other safeguards

In NFPA 12 systems, CO2 is discharged either by automatic operation or manual operation. On the other hand, in an enclosure where the technique for oxidant concentration reduction for deflagration prevention is used, its atmosphere is ALWAYS oxygen-deficient.

I agree with DM2 comments for cases where they have proved to be applicable.

As I said in my post # 3, not very often (I believe) most of us have to design protection for this type of materials. Your thread interested me and for the first time I read about protecting military explosives. I have put some amount of time in this. I invite other forum members to comment. I wish I could hear from a military explosives safety expert. I have no problem if somebody else proves that I am wrong because we would learn.

I would like to finally ask for information about the requirements established by:
• The Pakistan Government
• Local laws
• Pakistan military
• The weapons manufacturer
• Insurance company (if applicable)

Regards