Fire Dpt. Says Nat. Gas. Engine Generator Not Emergency

[Designer69]

This came out of left field, but I was informed by my GC that they were told by the fire dpt. that a Natural Gas generator is not considered emergency and only a Diesel generator can be considered emergency.

I've never heard of this anywhere in any local state or national codes. Mass. Bldg. code clearly does not state this.

Has anyone ever heard of such a thing?

 

[infinity]

The NEC states allows it when approved by the AHJ. I'm not sure what's changed but up until a few years ago we never installed a natural gas emergency generator.

700.12(B)(3) Dual Supplies. Prime movers shall not be solely de-
pendent on a public utility gas system for their fuel supply
or municipal water supply for their cooling systems. Means
shall be provided for automatically transferring from one
fuel supply to another where dual fuel supplies are used.
Exception: Where acceptable to the authority having ju-
risdiction, the use of other than on-site fuels shall be per-
mitted where there is a low probability of a simultaneous
failure of both the off-site fuel delivery system and power
from the outside electrical utility company.

 

[gadfly56]

The NEC states allows it when approved by the AHJ. I'm not sure what's changed but up until a few years ago we never installed a natural gas emergency generator.

700.12(B)(3) Dual Supplies. Prime movers shall not be solely de-
pendent on a public utility gas system for their fuel supply
or municipal water supply for their cooling systems. Means
shall be provided for automatically transferring from one
fuel supply to another where dual fuel supplies are used.
Exception: Where acceptable to the authority having ju-
risdiction, the use of other than on-site fuels shall be per-
mitted where there is a low probability of a simultaneous
failure of both the off-site fuel delivery system and power
from the outside electrical utility company.

For this reason, you will never find a natural gas fired fire pump. There may be a few in the hinterlands (I personally know of one) but you won't find new installs. Like, the last 20 years or so.

 

[Designer69]

oh boy I'm gonna be bankrupt. I didn't know that

 

[Adamjamma]

Natural gas lines, supplied by gas companies, can and usually are, shut off when fire departments request it. My cousin is a fireman who has said many times to me that I should not get a gas or natural gas generator as backup for my property because they are both more flammable than diesel. I am not an6 expert but can only say that when it comes to fire hazards, I listen to my cousin...he is the expert.

 

[infinity]

On our last project a 720 unit apartment building with some retail we used a NG generator for all life safety. First time in my career that I've ever seen that.

 

[ron]

We always get it in writing first from the AHJ before we consider natural gas for 700 or 701 gens.

I recently had it for a NJ gen and had to provide the letter back to the AHJ during construction and saved my butt

 

[publicgood]

We’ve had NG approved as long as they meet the 10 seconds in some areas of WI.

 

[gadfly56]

Natural gas lines, supplied by gas companies, can and usually are, shut off when fire departments request it. My cousin is a fireman who has said many times to me that I should not get a gas or natural gas generator as backup for my property because they are both more flammable than diesel. I am not an6 expert but can only say that when it comes to fire hazards, I listen to my cousin...he is the expert.

Your cousin is absolutely right. From a flammability risk, diesel is the way to go. The problem for emergency generators is that depending on the load they need to support, you may run into a problem storing enough fuel on site to meet however long it has to run. It may be as little as 24 hours, but in Florida they are requiring nursing homes provide power to run A/C for 96 hours. Most localities won't let you put that much fuel on your property, but natural gas is use it when you need it.

 

[USMC1302]

Some good points above. I agree with flammability, but I'm a fireman, and I'd want natural gas at my house all day long. Depending on your risk assessment, it would depend on fuel reliability in my mind. Earthquakes are possible here, but most extended outages have been blizzard/ice related that I have experienced. Natural gas interruptions have been extremely rare, and our emergency services building has a natural gas fired generator too. The other issue that has come up over time has been generators with large day tanks having stale fuel issues.

 

[Adamjamma]

Well, in the areas I have worked at the most, Natural Gas is not an option..not available so only petrol, diesel, and propane as options other than battery banks... thank god...

 

[Strathead]

This came out of left field, but I was informed by my GC that they were told by the fire dpt. that a Natural Gas generator is not considered emergency and only a Diesel generator can be considered emergency.

I've never heard of this anywhere in any local state or national codes. Mass. Bldg. code clearly does not state this.

Has anyone ever heard of such a thing?

The way I read the code cited, Propane could also be used.

 

[gadfly56]

The way I read the code cited, Propane could also be used.

If the property meets the storage limits (if any). Propane is flammable while diesel is combustible, so you are likely to be able to store more diesel than propane.

 

[brantmacga]

oh boy I'm gonna be bankrupt. I didn't know that

RIP. Hope it all works out.....:

But maybe you could see about changing the jets to LPG and adding storage tanks somewhere if the AHJ will agree.


Like others said, it’s pretty much always diesel. And you’d need to spec the tank size; specs usually require EC to include a full tank of fuel in the bid.


Sent from my iPhone using Tapatalk

 

[smoothops10]

Is an on-site propane tank an option? Talk to the generator manufacturer. You should be able to get a valve that switches to an onsite propane tank in the event of low gas pressure on the NG pipeline. Generator will have a reduced kW rating when on propane.

 

[gadfly56]

Is an on-site propane tank an option? Talk to the generator manufacturer. You should be able to get a valve that switches to an onsite propane tank in the event of low gas pressure on the NG pipeline. Generator will have a reduced kW rating when on propane.

Actually, it's the other way around. See one example here.

 

[tom baker]

In terms of KW capacity, a diesel generator will be smaller than the NG, as diesel has more energy than NG...not sure how to explain it.

 

[gadfly56]

In terms of KW capacity, a diesel generator will be smaller than the NG, as diesel has more energy than NG...not sure how to explain it.

I think the term you're looking for is "energy density". Per given mass of fuel, you get more energy burning diesel than NG.

 

[smoothops10]

Actually, it's the other way around. See one example here.

I'll admit I'm suprised, in the example you provided that looks to be true but that is a residential generator in 14kW range. I doubt OP is questioning about a generator this size. It is not the case for the larger sizes.

The project I worked on where we looked at the Dual Fuel NG/LPG (Automatic Changeover) option was a 350kW NG generator. The generator had a 355kW rating on Rich-Burn Natural Gas and only a 240kW rating on Rich-Burn LP Gas. Data sheet also indicated " For dual fuel engines, use the LP gas ratings for both the primary and secondary fuels."
http://www.kohlerpower.sg/onlinecatalog/pdf/g4191.pdf

 

[smoothops10]

In terms of KW capacity, a diesel generator will be smaller than the NG, as diesel has more energy than NG...not sure how to explain it.

Yes, this is true. One example I was given by a CAT rep was that a typical 1,000kW natural gas generator will use the same engine as a 2,500kW diesel generator converted for natural gas use.