How to refuel a diesel generator installed on a roof 6

[Gene M.]

Looking for some advice/opinion on an unusual situation...

A standby diesel generator is to be installed on top of a 7-story residential building. The original designer of this setup had put a storage tank at grade level on an elevated platform (high risk of flooding - why the gen is on the roof to begin with) and a pump set to provide fuel for it.

Unfortunately this person did not properly figure for the required property line and building setbacks for fuel storage tanks, so the AHJ will not approve it. It's been decided that the generator's 55-gallon day tank would be the only fuel supply. (The generator has already been purchased and everything else, except for the grade level storage tank/pumps and the generator itself, is already installed)

So now the problem I've been given to address is how to refuel the generator's day tank. Fire marshal will understandably not accept carrying cans of diesel up to the roof. We cannot have any storage at or below grade, both for lack of clearance and flooding concerns.

Is it possible, or sensible, to have a delivery truck pump the approximately 80 feet up to the generator's 55-gallon day tank? I've only ever dealt with gravity filled tanks so while I'm sure a delivery truck can provide the ~35PSIG it doesn't really feel right. Ideally I would at least have a small intermediate tank and pump set but there's no obvious place to put it.

Has anyone else ever had a situation with a fuel tank on a highrise roof? How was that install handled?

 

[3DDave]

Google: diesel generator on roof

http://www.usa-svc.com/pdf/InfoSheets/37.pdf

https://www.thebuildingcodeforum.co...enerator-on-high-rise-roof-in-penthouse.5812/

https://www.electronicspoint.com/forums/threads/diesel-or-gasoline-generator-on-a-rooftop.175848/

https://community.nfpa.org/thread/33258

https://www.ecmag.com/section/your-business/backup-generators-anew

Yet, while the power went out in many buildings, the power stayed on at Bellevue Hospital Center. Why? Bellevue employees and the U.S. National Guard hauled fuel up the stairs to operate the generators.​

 

[Hoxton]

I saw this very problem in London, some years ago.
I don’t know what the exact regulations were, but the tank next to the genset was limited to 100 litres and had to be tumescent for protection against fire
The was a bulk storage tank in the basement, covering several gensets.
From each genset tank was a dump line back to the storage tank, linked to the fire detection system.
So if a fire was detected, the fuel was dumped back to the basement.
This caused fun in commissioning because the fire guys tripped the system several times!
The fuel was pumped from basement to genset, but this was not part of our contract. Any filling overflow went down the dump line.
We did not used natural gas gensets at the time because of hazards, conceived unreliability of gas supply (you cannot store it on site.)
That's the way that the London Fire Brigade and the London buildings regulation people wanted it done.

 

[CWB1]

Some of you folks need to get out of the office occasionally, there are many diesel gensets on roofs stateside.

If an elevator goes within close proximity of the roof I would just point the delivery company to that. Diesel is easily moved in 55 gallon drums and extras could be stored on the roof given a basic containment plan. Barring that, I would look into a roof mounted hoist and drum clamp. Pumping from the ground is a bit needlessly complicated and would likely result in a line full of fuel remaining on the side of the building which likely wouldnt be looked upon too kindly by the officialdom.

 

[itsmoked]

CWB1; You are the third person to NOT READ the OP's statement that the fire marshal has nixed lugging fuel up elevators.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[3DDave]

That's the clue the fire marshal doesn't want this entire generator on the roof. At all. Ever. All other choices are worse because all the other failure modes are worse. The fire marshal isn't going to come out and say that a generator on the roof is not allowed because one without any fuel is never going to burn. Just making sure no fuel can ever get there is good enough.

 

[LittleInch]

I'm not sure that the fire Marshall has said that. I don't think the issue has been addressed properly. If you have diesel in the right sealed containers handled properly I can't see how the fire marshal can object.

It all depends on access to the roof about which we know nothing.

The alternative is then simply a small bore pipe up the side of the building (1" say) and a pump dipping into a 55 gallon drum. That reduces the diesel inventory to virtually nothing or you could drain it down after filling.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[pmover]

thinking outside the box, have you investigated alternate locations at grade level to install the genset? there will be electrical modifications and additional expenses, but at least the fuel hazards have been addressed.

 

[dvd]

Sounds like the perfect problem to solve with an attorney instead of an engineer.

 

[FreddyNurk]

If you have a site with a high risk of flooding, then there's also the likelihood that the site will be inaccessible for significant periods, and a much larger tank would be required to mitigate that.
If its not possible to provide a reasonable size storage tank for say, 3-4 days of autonomy, then in a flood situation it won't matter if you manage to provide a means to fill the 55gal tank from the ground, the truck won't be coming past in a hurry anyway.
The likelihood of this happening, of course, is rather remote, but based on that argument a backup generator isn't required either.

No matter what, it sounds like its going to be an expensive exercise for a number of people.

 

[GregLocock]

How about a moored pontoon with a decent sized tank, and a diesel powered diesel pump on it. If it floods, the pontoon floats up. If it needs refilling, it is at ground level.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[CWB1]

CWB1; You are the third person to NOT READ the OP's statement that the fire marshal has nixed lugging fuel up elevators.

Sure I did, I read that as an assumption on the OP's part. If a fire marshal stated they would not allow fuel to be transported through the building I would challenge them as to what ordnance or code was being violated. Given a valid legal prohibition the OP could then investigate the possibility of obtaining a variance based on risk mitigation, but at least the OP will then know its not a simple matter of an ignorant bureaucrat flexing their position (more likely in this scenario).

 

[LittleInch]

The quote in the OP is "Fire marshal will understandably not accept carrying cans of diesel up to the roof. "

My question would be why would he not accept this?

What is the highest floor you can access by lift?

Is there a goods elevator?

Do you have a machine room to store the odd 55 gallon drum?



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[SnTMan]

Is there a good elevator?

Do you have a machine room to store the odd 55 gallon drum?

Above the waterline I suppose...

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[FACS]

When is it time to take bets?

I want to bet on a natural gas conversion. It just makes much more sense.

 

[SandCounter]

Coming from a marine background where we pump fuel up to day tanks on higher decks, I would have a dry break coupling connection at the street and a globe valve with piping to the suction of a Viking-style PD fuel pump. After the pump, a check valve and then a pipe run up to the fuel tank. Have a limit switch on the tank up stairs to kill the power when the tank is full. You will probably need an E-stop at the pump and at the tank. Your industry-specific and local regulations will apply.

 

[chicopee]

To HYTOOLS"Is there a freight elevator? Haul 55gal barrels and use a hand pump to transfer fuel to the generator tank" perhaps a sensible way to get fuel to the roof but what IF the drum is puncture from let's say from a forktruck or handtruck and leaks fuel in the elevator shaft, or the drum tips over and gets punctured? Clean up or perhaps ignition of the diesel fuel vapor would be a nightmare. Piping natural gas (but not propane) would be a viable mean but of course the generator would have to have compatibility with the fuel.

 

[CWB1]

Fuel/oil drums are pretty difficult to puncture. I've personally handled hundreds, possibly thousands and seen them hit by all manner of equipment, forklifts, etc, and even fall 5' off the back of military vehicles with leaks being extremely rare, usually through the bung when stored on their side. If the choice of generator were left up to me I concur that gas would be the preferred choice if guaranteed to be available in an emergency, however I don't see hauling diesel as overly difficult or risky if an elevator gets them close to the roof. Any fuel delivery company should have drum dollies and spill response kits readily available on their truck.

 

[SnTMan]

Elevator working during the flood event? Enter it where?

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[itsmoked]

Deliver more fuel during a flood event? Drive it there how?

Just leave the fuel in the pipe, the natural gas pipe.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[dgallup]

Don't know the location but in seismically active areas the supply of natural gas may be shut off during an emergency.

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