×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Generator room ventilation

Generator room ventilation

Generator room ventilation

(OP)
Hello everyone,

I was looking for requirements on ventilating a generator room. Does it have to only be naturally ventilated?

I've looked at NFPA 110 (2008) but it seems ambiguous.

RE: Generator room ventilation

Do an engine search. By just typing "indoor generator fresh air requirements" I got multiple hits.

RE: Generator room ventilation

You will need both combustion and cooling air which will be cataloged by generator manufacturers.

RE: Generator room ventilation

(OP)
Well, for the cooling air, can it be coming from a cooling coil?

Because one of the concerns is that if we're using a cooling coil and if it failed at the same time that the generator was required, then you'd end up with inadequate cooling and so we're trying to see if there is any code requirement mandating only the use of OA dampers to condition the generator room.

RE: Generator room ventilation

When you say cooling coil, are you referring to a radiator being part of the generator? As stated above, manufacturers' catalog will provide you all the info.

RE: Generator room ventilation

(OP)
No, the radiator itself is mounted on the roof. But we'd still need to handle the heat load from the generator. I'll look up the manufacturer's specs and see what they have to say.

Thanks chicopee and willard3 for your advice.

RE: Generator room ventilation

NFPA 110 (2016) consistently uses the word "ventilation" when discussing cooling of the generator room.

The definitions section of NFPA 110 says for words that aren't specifically defined in the standard use the common dictionary definition.

The common dictionary definition for "ventilation" is "provide fresh air from outside".

So, yes it has to be only natural ventilation.

RE: Generator room ventilation

(OP)
I was thinking on the same lines. Thanks MintJulep!

RE: Generator room ventilation

I am from marine sector and always use ISO8861

RE: Generator room ventilation

No - wrong interpretation of the word Ventilation.

ventilation does not mean natural ventilation in our trade, you should not go by what the dictionary says, but by how your industry defines the word ventilation, i.e. as defined by IMC, not by the webster.

IMC defines Ventilation as follows:
Ventilation is defined as the Natural or Mechanical process of supplying air.
Ventilation Air is defined as the portion of any supply air that comes from outside plus any recirculated air.

Use exhaust fan with Outdoor intake with filters, dampers, thermostat, the classic ventilation, account for combustion air. That's it.

RE: Generator room ventilation

Sorry cry22, but you're not right.

NFPA 110 explicitly tells you to look it up in the dictionary.

Quote (NFPA 110 (2016))

Where terms are not defined in this chapter or within another chapter they shall be defined using their ordinarily accepted meanings within the context in which they are used. Merriam-Webster's Collegiate Dictionary, 11th edition shall be the source for the ordinarily accepted meaning.

RE: Generator room ventilation

Mint,
Nope, allow me to disagree.

NFPA 110 is not one of the referenced standards in IMC. We design per code. The code is IMC, not NFPA 110.
NFPA is a guideline unless referenced by IMC.

and I agree with IMC for the Ventilation definition, not with NFPA 110.

AND, if you read your quoted text correctly, it says "ordinarily accepted meanings within the context they are used" - What NFPA is saying in the quoted text is that when NO specific definition is known, then you rely on the dictionary. But there is a Known definition as defined in IMC.

I love it, we talk like lawyers.

RE: Generator room ventilation

Look at the generator manufacturer literature, they should refer to the installation requirement.

RE: Generator room ventilation

Here is a source for details and schedules for most of young engineers that I am sure will find helpful

http://www.cfm.va.gov/til/sdetail.asp

check the emergency gen set detail from the same site below, this one has a radiator indoor, just edit to suit the remote radiator application. The remote radiator application is actually much simpler.

http://www.cfm.va.gov/til/sDetail/Div23HVACSteam/S...

317069: gen set manufacturers do not issue installation details, they just issue air flow requirements.

RE: Generator room ventilation

Cry 22
air flow of what?

RE: Generator room ventilation

317
air flow for radiator (when radiator part of gen set), combustion air flow, alternator cooling air flow.

RE: Generator room ventilation

cr.
Young engineers are happy with grandpa gift.
also, didn't Caterpillar give you installation details such as clearances around generator, ambient temperature, room temperature and condition if it was for indoor application.

RE: Generator room ventilation

Have to agree with Cry22 regarding the definitions and that IMC is the governing code.
IMC defines "Ventilation" as "The natural or mechanical process of supplying conditioned or unconditioned air to, or removing such air from, any space."
And "Ventilation Air" as "That portion of supply air that comes from the outside (outdoors), plus any recirculated air that has been treated to maintain the desired quality of air within a designated space."
Furthermore, IMC does not specifically define mechanical ventilation, but does define "Natural Ventilation" as "The movement of air into and out of a space through intentionally provided openings, such as windows and doors, or through nonpowered ventilators."
If Natural Ventilation is ventilation using nonpowered means, then Mechanical Ventilation would be the use of fans to force the ventilation air through the designated space.

Doing a word search through NFPA 110, I do not see anywhere specifying that the ventilation air to be either natural or mechanical. Thus I would interpret NFPA 110 to mean that the ventilation air can be either natural or mechanical in nature.

Going back to Sidd20's OP and his question

Quote (sidd20)

Does it have to only be naturally ventilated?
my answer would be no, it does not have to be only naturally ventilated.

RE: Generator room ventilation

Why IMC is governing code?

RE: Generator room ventilation

In the US, at least, each state determines a code to which they want buildings constructed to. For most states this is ICC's building codes including IMC. Select states such as Florida and New York have their own building code which are based on IMC. DOD and other US governmental agencies use IMC with select changes. I have yet to see any of these modified versions of IMC change definitions.

RE: Generator room ventilation

cry22 and dbill74 are on the right track with this. Where there are defined terms in an applicable code, use the code definition.

IMC may very well govern, check with your local authority having jurisdiction.

RE: Generator room ventilation

If you have a genset with a remote radiator you will still need an enormous amount of ventilation air to cool the generator room. I recently did a generator room with two 2000kVa water cooled generators and required 25,000L/s ventilation to maintain a 18 degree temperature rise in the room over ambient temperature.

You need to talk to your generator supplier to confirm the heat that the generator radiates into the room, determine the maximum temperature you can allow in the room, your design ambient temperature and then calculate the air flow. Plus you need to make allowance for combustion air which won't be as large, but is not insignificant either.

The next issue will be acoustics and large airflows need large attenuators!

RE: Generator room ventilation

wish I'd had this problem when running two 1000 kW gennies in the high arctic when April was still minus 40

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources