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?

 

[handleman]

Haaaaaa hahahahhahahhaahhaaaha hahahaaaaaaaaaaa

Sorry, this is absolutely not your fault, but I find this post quite hilarious...

There are some absolute geniuses over in this thread:

https://www.eng-tips.com/viewthread.cfm?qid=463804

I'm sure someone can figure out how you can put a pump up on the roof out of the way of everything. Maybe an archimedian screw?

But really... I would ask your fuel delivery company about the truck's capability. I have zero experience in this area, so I'm totally shooting from the hip, but I'd be a bit surprised if there's pressure available beyond the head from the tank height on the back of the truck. Probably also need to check into the code for the pipe. And I'm not sure how happy the fuel will be sitting in the 80ft pipe for a long time either. This is an emergency backup generator right? So refueling is rather infrequent? You may want a bypassable check valve to drain it back into a suitable container.

 

[RVAmeche]

Would it be possible for the building to have a small truck off load/booster pump station? The truck would hook up and pump out the fuel to the suction side of a permanent/portable pump that then gets it the rest of the way to the roof. It shouldn't take up a tremendous amount of space...but if you have to have the pump installed inside that may create other issues.

I agree w/ asking the fuel delivery company and seeing what their truck can do and if they have any recommendations.

 

[MintJulep]

80 feet, 35 psi, water.

I don't expect that a typical oil delivery truck has any way to deal with disconnecting the filler hose/nozzle under pressure.

You'll also have a pipe full of oil always.

 

[MintJulep]

Oh, and 55 gallons?

Maybe 5 hours to suck that dry.

 

[Strong]

Besides the fuel delivery issue, how the other issues such as noise and vibrations accommodated? Has the engine been run yet to see, hear, and feel what happens?

Walt

 

[RVAmeche]

Most fuel delivery trucks have hoses w/ cam-locks or quick disconnects that can interface with piping.

 

[Gene M.]

handleman: Believe me, I appreciate the humor in the absurdity of it all. Contacting the owner to see if they have a fuel delivery company they already deal with is a good thought; I'll follow up on that for sure!

MintJulep: Yeah that was my immediate thought, too. Even with check and shutoff valves at the fill point there's bound to be some spillage with that setup. (FYI: based on the gen's datasheet the day tank should last at least 8 hours at full load, probably at least 10-12 hours in practice, but the owner was made aware of that)

Strong: The generator is sitting in a yard somewhere waiting to be delivered to site. It's been sitting there for almost *two years* at this point! Will probably be trash by the time this gets resolved; but maybe then I can justify telling them to get a natural gas one instead. Other than that, I can only assume the structural guys did their job.

 

[handleman]

My apologies if I wasn't clear... Your post, standing on its own, is 100% reasonable and presents a valid problem to be solved! I certainly didn't intend to cast aspersions in your direction. The comedy comes in its uncanny similarity and temoporal proximity to the discussion in the thread that I linked. Which you are free to ignore as it doesn't actually contain anything of value. Just nerds arguing about a hypothetical situation involving a building, and tanks, and (maybe?) a pump placed... somewhere.

 

[JStephen]

I would think the fuel guys would be very hesitant to start pumping fuel to some place they couldn't see. I can just see them pumping 400 gallons up there and it's gotta go somewhere.
Years ago, I worked for a company that had an above-ground gasoline tank for trucks. The gasoline delivery people had trucks that could handle that- but it wasn't every truck. So periodically, there would be a screw-up, and they'd get the wrong truck out there that was set up for gravity flow into underground tanks only.
Can you install a davit and hoist cans up the outside?

 

[nackra]

is natural gas available as an alternate to diesel?

 

[IRstuff]

I'm tempted to think that daily delivery of 55 gal of fuel is going to expensive and annoying. You're looking at delivering less than 1% of the capacity of a typical fuel tanker, and all the operations that entails that are exactly the same for delivering 2500 gals.

Running a fuel truck into a residential area every day seems like an accident waiting to happen and if the setback is that tight, the tanker might need a longer hose to get to the inlet and the potential inconvenience to occupants and other traffic that engenders.

Additionally, that also means you have essentially zero reserves; if you miss a delivery the generator and its electrical output is down.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529 Entire Forum list

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[LittleInch]

Lets get real.

This is a standby generator so once in a blue moon. Can't you just drag up a few 55 gallon drums?

Or use a 55 gal drum and a small pump?

You can roll metal drums across to the wall.

Or store a few on the roof?

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

 

[DAVIDSTECKER]

It sounds like a pump has already been selected for pumping fuel to the roof from the original plan.
Do you have that pump?
There are "Zero" leak quick disconnect hydraulic fittings that are fairly large flow rate.
Actually you may want to look to the hydraulic world for your solution instead of household plumbing.
Most hydraulic pumps are good for at least 3,000 PSI with 32 WT oil.
I think with a 5 HP motor you should be around 5-10 GPM.
My first thought would be to look at piston pumps vs gear pumps.

 

[chicopee]

Personally, if I were the housing inspector, I would have the generator relocated at ground level. If flooding is a potential threat then elevate the generator on a platform placed at ground level. Think of the potential cleanup problem of diesel fuel leaking on the roof and about the possibility of loosing insurance coverage. The extra cost of rewiring the generator should not be a significant factor.

 

[dgallup]

Obviously you use drones to carry the fuel to the roof. Just ask Jeff Bezos.

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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[itsmoked]

Dump the generator and get a natural gas unit. Selling the unused/uninstalled generator will be very easy.
Selling the existing generator and replacing it with a NG unit will save a large amount of money over any conceivable liquid fueled solution available to this overly constrained situation.

This completely removes the permitting and inspection requirements associated with liquid fuel storage. It will also avoid the catastrophe of a roof spill that will promptly dissolve most roofing materials.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[moon161]

^ That was almost my answer to the linked thread. Use mcmaster-carr, order a filled drum, deliverable to the roof.

 

[TheTick]

 

[hydtools]

Is there a freight elevator? Haul 55gal barrels and use a hand pump to transfer fuel to the generator tank.

Ted