We have a hospital project where th 1

[PagoMitch]

We have a hospital project where the architect has changed our tanks from (2) 15,000 gallon tanks (22'H) to (1) 30,000 gallon tank (36'H). Due to other reasons, the available area has shrunk.

The change has generated (2) problems which have me between a rock and a hard place.

#2 diesel, in a tropical environment. Double wall, NFPA 30 and UL142 compliant Fuel tank serves (3) 100 GPH generators, and a Heating Hot Water boiler. Storage capacity is based up 96 hours run-time for all hardware.

Problem 1: The lead players in submersible pumps (both Franklin Fueling and Red Jacket) offerings only extend to a nominal 20' of shaft length.
With my original tanks I was fine. Now, it seems that no one makes a submersible pump for diesel fuel with a longer pickup. I am not sure why.
As I look out my window, I see the well head for my water pump; which is about 325' deep. Diesel fuel has less density that H20... so I fail to understand why no one make a "deeper" submersible pump.
The only think I can think of is that they are bumping up against physics, in that you can only suck - theoretically - 30'; like for an Oberdoffer gear pump. But a SUBMERSIBLE pump is -I assumed- just that. It is fully flooded at startup. Just like my well pump.
A couple pump vendors have suggested doing a tap off the side of the tank at grade and installing a "Pig Pump", as they called it. Problem is... se problem #2 below.

Problem #2: NFPA 30, para 22.11.4.2 requires "All piping connections to the tank shall be made above the maximum liquid level.

So. The dearth of an available submersible to reach 35 (or so) feet means I need to put something on grade, and NPFA 30 prevents me from tapping into the tank below the liquid level.

The only thing I can think of would be to use a grade-mounted gear pump, run the piping up the side of the tank to the top, make a u-bend, and then extend the piping down to appx 1' above the tank bottom. ASSUMING that (1) I could manually prime this system, and (2) the foot valve on the interior never fails, this should work. But if the foot valve fails, or the suction piping springs an air leak elsewhere, the system would not be self-priming, no fuel would be pumped, day tanks would empty, generators would fail, and darkness would ensue. Not good.

This can't be the first time a tall diesel tank has been used to provide fuel storage at a hospital. How do you get around this dilemma?

TIA.

 

[JStephen]

"Now, it seems that no one makes a submersible pump for diesel fuel with a longer pickup. I am not sure why."
Googling up some of the information on these two brands, it looks like they are intended for horizontal tanks, so the maximum size limitations of shop-fabricated tanks also limits the maximum pump depth they'd ever require.
If you haven't done so, perhaps contact both those venders and see if they can offer any solutions for a taller tank. It's not immediately obvious to me why they couldn't build an extended version if required.

Secondly, in googling up some info on this, I ran across this page, which sounds promising on the surface at least:

https://www.northridgepumps.com/article-94_what-are-vertical-immersion-pumps

Tanks of these dimensions are not at all uncommon, but the ones I see are generally single-wall, so this issue doesn't come up.

 

[3DDave]

As long as there is fuel in the tank the u-tube would remain filled as it is a siphon. The bad result is from a leak outside the tank that causes the siphon to empty the tank.

Your flow rates look very far below the capabilities of these pumps.

I agree the depth should be available, and also with JStephen that the makers have a market for their catalog items and are advertising to sell to that market. Contacting them for a custom riser is your best bet.

Another item to keep in mind is that 30 foot limit is at sea level as that is the depth of water that matches the local static pressure. Diesel is a bit less dense. Technically you could put a bit of pressure into the tank to start a siphon - whatever the gap between the surface of the fuel and the top of the siphon - 1-3 psi would cover a good range.

 

[PagoMitch]

JStephen - thanks for the reply - and the link!

Franklin Fueling was my selection for our previous tank - 22' in height. The Rep did not know why - nor seem to care - about his company not making a pump with a shaft >20'.
Neither Franklin nor the Goulds vendors expressed an interest in providing a custom solution. Still waiting for a call from Red Jacket. The Goulds guy had some... odd reasons why they could not do it: "the bearings would need to be bigger", and "you would need more intermediate supports". I said "fine, can you do it?". His reply was "it would probably cost more money". Not the best sales rep I have ever encountered.

The page you linked to seems to give me a great starting point. Seems a "Vertical Immersion Pump" is worlds apart from a "Vertical Submersible Pump"... go figure.

I looked at several search pages, and it appears that of the 5 vendors I found, only the (2) UK vendors (North Ridge and Castle) can seemingly provide pumps with a pit depth greater than 6-26 feet. Will need to spend some more time on this tomorrow; While I am glad to say they make the style pump I seek, their capacities GPM) are about 4X what I need.

Thanks again.

 

[LittleInch]

Can you sketch up what you have here and define what you mean by submersible pump.

I think you mean a pump where the motor is on the surface and you have a long shaft to the pump which essentially hangs off the bottom of the motor?

There are many types of truly submersible pumps more like a water borehole pump. Would one of those not work?

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

 

[Andrew ONeill]

I don't have any experience in diesel, but I think the magic description you are looking for is a "vertical can pump", "can" being the various modules / cans that bolt together, each with a bushing to guide a long shaft. From memory there is even an API standard that deals with design of the shaft for this type of pump to avoid resonance issues etc. I have no idea if anyone makes one for pumping hydrocarbons, but it should get you in the right direction.



Andrew O'Neill
Specialist Mechanical Engineer
Australia

 

[PagoMitch]

LittleInch - the (2) types are indicated in the attached sketch. I still do not know why no one makes a "submersible" pump with more reach. But if I can find a "immersion" pump that works, I'll be happy with that.

Andrew - A "Vertical Can Pump" certainly seems like an apt description. I am still waiting for the folks in England to get back with me.
They had all day yesterday to respond to my query sent last night,(there is a 8-hour difference between Tucson AZ and England), but like many firms they seem to take awhile to get back to you. So I sent them another email today.

 

[LittleInch]

Pago,

Some of this is terminology mix but for me a submersible pump can be any length.

I think - a link to the relevant vendors would help, is just that you're looking at pre packaged self contained submersible pumps inside the delivery line with the power cable either inside it or strapped to the side and presented as a nice neat package to drop into a flanged connection??

The problem nowadays is that once you go outside the "normal" or 80-90% range no one is interested in a "one off" design. I would try once and then give up. My guess is that beyond 6m/ 20 ft, the tube just gets too unstable and the weight of everything starts to get to the point where you need extra thickness and thicker flanges etc etc.

The pump on the right is also know as VS types pumps to API 610.

So you need to do it your self.

There are many many hundreds of thousands of borehole submersible pumps available which fit down a 4" or 6" pipe. Most are designed for water, but I'm sure there are many able to handle diesel.

They either then have a flexible hose which you then need to connect to or some will seal into the end of the tube with the cable inside which then exits via a sealed connection. The pump comes with wires to extract it if required.

Or just drop a fully submerged pump down to the floor through a manhole sized connection and then run the cables through a gland.

Many ways to skin this cat.

I had to go look up that NFPA code reference as its a bit odd to me that no one will make a tank with connections, but I guess if you're going for a double skinned tank then that's what happens...

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

 

[PagoMitch]

LittleInch - Yep, that is what I am looking for. But the (2) primary vendors of that type of pump (Franklin Fueling and Red Jacket) only extend to a nominal 20 feet; and they were not interested in doing any custom work.

I have tried Goulds and B&G and ITT and Gorman Rupp and Macdonald and Vertiflow and Castle (England) and Flow Solutions and RAE and Taco and Anderson and Grundfos and Process Systems, and probably a few others - for either a submersible or an immersion or a fully submerged pump that is rated for diesel fuel. I did find a couple vendors could meet my specs (30 gpm @ 60' head) with a stainless explosion proof pump; but they were intended for sewage treatment, and they would not provide them for diesel service. Seems to me that a change in o-ring polymers might solve that... but again, no one was interested.

I did find a cool vertical Rail System that would allow the installation and easy removal of the fully submersible type pump; but again, no one seems to offer a pump.

In reality, I do not HAVE to use a double wall tank. But if I were to use a single wall, I would be required (again, per NFPA 30) to provide a dike around the tank equal to the tank's contents in volume. This is what Tank farms use; but we do not have that space available on the site. we literally have buildings on 2 sides, and roads on the other 2.

The only ways I can find to skin this cat is using the "North Ridge" Immersion ump in the UK. That is not without its own set of challenges, re: UL construction, NEMA motors, 50 Hz; but I believe those are at least solvable.

 

[LittleInch]

They might be a bit over specced, but have you looked at downhole ESP pumps for oil wells?

If they can pump crude oil in sure they can pump diesel....

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

Also you don't need to provide a large bund of the same volume. you can simply insert the tank into a metal tube / cylinder very slightly bigger than the tank. you just need to provide drainage points and some grids to stop animals falling in. The tank itself is included in the calculation of the bend volume.

That would solve ALL your problems?

Like this

https://www.3diequipment.com/product/35000-litre-chem-resist-bunded-storage-tank-2841/

 

[PagoMitch]

LittleInch - Interesting; I have never seen that system before. While it would certainly pump our #2 diesel, I would guess that that industry is not required to comply with NFPA 30, which pretty much dictates steel for AST's, with steel or FRP for UST's. While I like the idea of simply inserting this polyethylene tank into a steel "liner", I would not want to argue with the AHJ that that merging of these systems would meet either the letter or the intent NFPA 30.

That said, there appears to be some motion by our Architects to alter the building footprint that would allow me to back to a pair of 20' tall tanks; for which the Franklin Fueling or Red Jacket Submersible Vertical Pumps will suffice.

To go off in the weeds...The project funding source is ARPA, and the application was for a two-story Central Plant. Then the client directed us to provide a single story design; but when the ARPA Admin received our prelim design, they stated it did not meet the application criteria, and directed our client to go back to the two-story design - which then allows me the footprint to provide the (2) 20' tall tanks.

Sometimes the easiest way to solve a problem is to avoid the problem.

 

[LittleInch]

That was just an example - I've seen steel inside steel or steel inside concrete or "plastic".

The issue usually is how do you get the pipe penetration through the outer shell without creating a hole which could leak.

But it is done.

No idea what ARPA is....

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

 

[3DDave]

American Rescue Plan Act, probably.

 

[IFRs]

The tank inside a steel dike configuration is quite common. Both tanks are designed for liquid containment, the inside tank is usually taller. They can share a bottom and a foundation. Piping between them is easy since both tank shells have flanged nozzles. Your issue of pumping vertically seems to boil down to how do you prime the system since once it starts it goes almost by itself. Have you looked at PD (positive displacement) pumps?

 

[georgeverghese]

See if these folks can help :

https://www.sulzer.com/en/products/pumps/pumps-by-type/submersible-pumps

 

[PagoMitch]

LittleInch - yep, American Rescue Plan Act. Lots of $ being passed around, with lots of strings attached.

IFRs - no room for a conventional dike. Would also probably be difficult to design with the local 200" of rain annually! I have used positive displacement pumps in the past, but I have never seen them submersible, and they were all limited to physics, with 20 (or so) feet of head on the suction.

georgeverghese - I tried literally half a dozen US submersible pump vendors - all had pumps more than sufficient to meet capacity (flow and head), but none of them were rated for #2 diesel fuel. None.

After all this, finally convinced the architect that we could not meet the pump requirement in that configuration; without 35' long assemblies manufactured in England and then shipped half-way around the world. So they are modifying the bldg to allow us to go back to the (2) 22' tall tanks; for which a conventional submersible pump from either Frankin Fueling or Red Jacket are pretty much off-the-shelf.

Thanks again gents.

 

[IFRs]

You have solved your problem, but FYI it is not hard to have a fixed sloped roof that is attached midway down the inner tank that rests on the outer tank to shed rain or snow and not fill up the interstitial space.