NFPA 99 - Dedicated Exhaust for Med Gas Storage Room

[PagoMitch]

I am designing a couple small Med Gas Storage Rooms in a Hospital; (4) K cylinders each of N2 and CO2 (about 300 ft^3 each tank, 1200 ft^ 3 each room, 2400 ft^3 on this floor). These will be in separate rooms, although it is technically not required.

NFPA 99 2018 requires 1-hr walls, with 45-minute door and opening protection. This is in spite of 1-hr walls NOT needing protection (fire dampers) per NFPA. OK, so be it.

My question is on the exhaust:
Ducts down to one foot from the floor - no problem.
Exhaust at 1 CFM/5 ft^3 tank volume - no problem.
Non-combustible Exhaust Duct - no problem.

However... "Para 9.3.6.5.3.5: Dedicated exhaust systems shall not be required, provided that the system does not connect to spaces that contain combustible or flammable materials". OOPS, problem. This was going to connect to the Central Exhaust System, a nominal 5000 CFM Fan that serves roughly 16000 SF.

I cannot think of any enclosed area, anywhere (except for maybe an empty prison cell), that would not contain "combustible or flammable materials". Papers on a desk, a wall calendar, seat cushions, a wooden desk, wooden filing cabinets, manilla folders, the paper covering on an exam table, paper towels in the bathroom, cardboard boxes in the Janitors Closet holding cleaning supplies, and even the paper bags from In-N-Out burger would all be combustible, with the In-N-Out bag in particular (probably) being flammable due to the grease coating.

The way this is written, EVERY Med Gas Storage Room, even those at a miniscule 12 SF would require a dedicated Exhaust System.
I did try looking at definitions for "combustible or flammable materials" in NFPA, hoping it would be defined as Types of Construction - no such luck.

Am I missing something, or is this paragraph as literal - and inane - as it appears?

TIA.

 

[PEDARRIN2]

From the commentary.

 

[PagoMitch]

Pedarrin2 - Thanks for the response.

I understand the Code - I quoted it.
However... the way it is written is appalling.
"... cannot interconnect with other facility air-handling systems that serve locations containing combustible or flammable materials".

For pete's sake... An employee in a Hospital of concrete and/or steel construction, with a concrete floor and steel furniture - that may reasonably be construed as NOT containing combustible or flammable materials (assuming it is a true paperless office, and no one brought in today's copy of the Wall Street Journal to read at their desk), would VIOLATE that construal by bringing back a hamburger and fries in a paper bag, or (if she smokes), leaving her Zippo in her purse. Most codes are written with a little less arbitrariness, with violations not dependent upon the packaging of what someone brings for lunch.

I had hoped... that as this code has been in place since at least 2012, that ...someone... may have challenged this, or got an interpretation a little more rationally written. This could have been on defining "materials" as "construction materials", and defining their performance per ASTM E-84 "Flame Spread Rating", or E-119 "Fire Rating". THAT... would have made a lot more sense. Alas, apparently not.

In this case, the facility is in the tropics, and having an opening from tank gases (which cool appreciably as they are being used) to the very high humidity ambient temperature is a recipe for lots of mold. So I will need to provide conditioned (and dehumidified) are as make-up. Which we have.

There is another line of thought... are we really concerned with inert gases in industry standard pressurized containers bursting into flame? Sigh.

Regards.

 

[3DDave]

It would seem that contacting the issuing authority for clarification or remediation of this section would be the most effective approach.

 

[PagoMitch]

3DDave - Thanks for the reply.

In this case, as in many... neither I, nor the facility has the time to fight this borderline idiocratically (apparently not a word, but it should be...) written code section.

So instead I'll finish the design in compliance with NFPA, and the facility will spend in excess of $10k on a dedicated fan, ductwork, fire dampers, grilles, louver, controls, shipping everything 5000 miles, and then installation and air balancing.

Speaking of fraud, waste and abuse...

Sigh.

 

[3DDave]

NFPA isn't a government agency. It is an industry organization that is mainly in place to protect the members as well as customers.

Not sure that sending an e-mail is a "fight" but if you have standing on an actual project to make a request and choose not to then that contributes to the problem.

 

[Vinny-wong]

why (which cool appreciably as they are being used) ?not liquid change to gas,only compressed gas to gas

 

[PagoMitch]

3DDave - Point taken... But this project has been under construction for over 10 years... 10 years of Construction Admin weekly meetings on a project literally 5000 miles away, that was to have had a 24-month schedule. I just cannot keep fighting every issue; especially one involving a request for a code alteration/change. That said, I have done this - successfully - in the past; but in my two endeavors of this type, it took several months of letters/hearings/communications to get a ruling. In this case, the Med Gas certifier flagged the problem, and getting it resolved is holding up the final commissioning of the Med Gas System; which is one of about a dozen items holding up the opening of the project.

One thing I have learned in my 40 years in this business, is that you have to prioritize your battles.

Vinny-wong - Not sure what you are saying; but most gases cool upon expansion. As that happens, the gas molecules move further apart, and this expansion requires energy, which is typically drawn from the gas's internal energy, leading to a temperature drop. Joule-Thomson Effect.

 

[3DDave]

Dear NFPA,

I have the following question.

Does the entirety of a building interior constitute an air-handling facility for the purposes of evaluating the storage of medical gases and therefore require that non-hermetic sealing and sending of gases to patients means that somehow "Para 9.3.6.5.3.5: Dedicated exhaust systems shall not be required, provided that the system does not connect to spaces that contain combustible or flammable materials" demands that any storage of non-flammable medical gases requires a separate exhaust system?

I have a case where only N2 and CO2 are being stored, classified as medical gasses, and am looking at a very expensive retrofit to provide against flammability.

Thank you for taking time to evaluate this and I look forward to a response.

Sincerely,
Your name here.

NFPA contact -> https://www.nfpa.org/about-nfpa/contact-us

There you go. The entire battle. If that's too much then one thing I have learned in 45 years of engineering is to read the contracts before signing them.