Surge Tank & Fuel Pump location - cabin or engine bay

[charlie]

Hi there. I would like clarification please regards fitment of a surge tank and fuel pump.

Let's assume for a moment there is no boot.  That leaves only the cabin and the engine compartment as candidates for surge tank and fuel pump location.
This might be true of station wagons or a mid-engined car with no boot (a heavily modified MR2 perhaps).

Looking at the HCTM chapter 10 regards fuel systems:

lvvta.org.nz/documents/suplementary_information/HCTM_SAMPLE_Chapter-10_Fuel%20Systems.pdf

Here's my understanding of the rules. Please clarify or correct me if needs be, thanks. 

Regards placement of a surge tank and pump in the cabin:

10.2.1
A fuel tank and its related fuel system components may be located within the boot or passenger compartment of a low volume vehicle, provided that the requirements specified in 10.4 and 10.5 are met.

Looking at those sections:

10.4.1
A low volume vehicle that has a fuel tank located on top of the floor surface, must have the floor and surrounding area in which the fuel tank is located, designed in such a way that any fuel, in the event of a fuel tank leak or rupture: (see Diagrams 10.1 & 10.2)

(a) cannot come into contact with the vehicle’s battery or battery leads; and
(b) will escape to the outside of the vehicle, without draining onto either:

(i) any part of the vehicle’s exhaust system; or
(ii) any part of the vehicle’s electrical system.

Q: So the surge tank needs to sit in a section of the floor designed to act like a funnel and that section needs a drain hole through the floor to the ground. Correct?

Q: Do the words "floor and surrounding area" mean that a surge tank fitted in the cabin needs to be fully enclosed in some kind of box?

Diagrams 10.1 and 10.2 both show a fuel and vapour proof bulkhead.

Yet section 10.4.2 seems to suggest that a surge tank does not need to be isolated from the passenger compartment as it has no filler cap and functions as a sealed unit:

10.4.2
A low volume vehicle that has a fuel tank located on top of the floor surface, and can be filled from inside the trunk or passenger compartment, must have an isolating panel made from a fuel- resistant material to prevent fuel, or fuel vapour, from entering the passenger compartment.

So my understanding would be as follows:

If the filler cap is merely the OEM one on the main fuel tank and the surge tank is filled only by way of fuel lines then 10.4.2 means I am not legally required to fully enclose (isolate) a surge tank if it's in the cabin, because it cannot "be filled from inside the trunk or passenger compartment".
Q: Is this correct?

Q: Legalities aside, if I were to enclose it in some kind of box as an added safety measure (this would seem sensible in case of a leak etc) are you able to point me at a relevant specification please?  Or does the interpretation of "fuel resistant and vapour-proof bulkhead" (diagrams 10.1 and 1.2) rest with the certifier?

Section 10.5 deals with venting, and is therefore irrelevant where a surge tank is concerned as far as I can tell, because there is no venting from the surge tank. Only a return line back to the main tank.

Q: In a nutshell, if I were to mount a surge tank and pump in the cabin, do they need to be fully enclosed in a box to isolate them from the cabin? As far as I can tell by reading the regs, the answer would seem to be "legally, no.. but it would be a sensible move".

Please advise. 

OK, what about mounting a surge tank in the engine bay?

I return to section 10.4.1

10.4.1
A low volume vehicle that has a fuel tank located on top of the floor surface, must have the floor and surrounding area in which the fuel tank is located, designed in such a way that any fuel, in the event of a fuel tank leak or rupture: (see Diagrams 10.1 & 10.2)

(a) cannot come into contact with the vehicle’s battery or battery leads; and
(b) will escape to the outside of the vehicle, without draining onto either:

(i) any part of the vehicle’s exhaust system; or
(ii) any part of the vehicle’s electrical system.

Q: The engine bay has no floor. A surge tank mounted in the engine bay is therefore not "located on top of the floor surface". Is this correct?
I ask, in case I have misunderstood the definition of "floor surface" or something.  For example it doesn't refer to some imaginary line drawn through the car from end to end, does it?

Q: Does this mean it is OK to fit a surge tank and fuel pump in the engine bay? No isolating panel required? For example if the surge tank and pump are located away from the exhaust and not above it or any electrics, is the engine bay legally an ok place to fit them? Please confirm.

I have one last question regards the hose and fittings in the cabin, if I were to fit a surge tank and pump there.

10.2.1
A fuel tank and its related fuel system components may be located within the boot or passenger compartment of a low volume vehicle, provided that the requirements specified in 10.4 and 10.5 are met.

This states it's ok to fit both a surge tank and pump in the cabin as long as the requirements of sections 10.4 and 10.5 are met. But I am left with a question regards the fuel lines required to do so. Namely, the line from the surge tank to the pump. 10.8.5 (d) seems a bit confusing:

10.8.5
Rigid fuel pipe or flexible purpose-designed automotive braided stainless steel covered hose may be located within the passenger compartment of a low volume vehicle, provided that:
(a) the hose cannot come in contact with either the driver or other vehicle occupants during normal vehicle operation; and
(b) the pipe or hose is secured firmly against the floor at intervals of no more than 300 mm (12”); and
(c) the hose can be readily inspected for wear or damage; and
(d) there are no pipe or hose joins or connections inside the passenger compartment, other than for purpose-designed bulkhead fittings.

Q: Can I fit a surge tank & fuel pump in the cabin, with a line in the cabin going from surge tank to pump as long as it meets the requirements of 10.8.5 (a) (b) and (c), and with the other lines going directly to bulkhead fittings like this one: www.aeroflowperformance.com/fittings/bulkhead-fittings/bulkhead-an/af832-10

Thank you in advance for your patience in answering these questions as fully and precisely as you can. Your help is very much appreciated and is sure to helps others in the future. 

[Leon]

Hi Charlie,

I haven't forgotten you, but it's a biiiiiiiig question, so I'll need to do a pretty big answer, and I'm a bit buried up to my ears at the moment

Watch this space!

[charlie]

Looking forward to your answer Leon. Thanks.

[Leon]

Right, lots of answers follow. Hopefully I can format it so it all makes sense ...

Q: So the surge tank needs to sit in a section of the floor designed to act like a funnel and that section needs a drain hole through the floor to the ground. Correct?

Yes, correct. So that spilled petrol will go away in a controlled and designed manner, rather than remain a pool of petrol keeping you company, or dribbling out a hole onto a nice hot exhaust system.

Q: Do the words "floor and surrounding area" mean that a surge tank fitted in the cabin needs to be fully enclosed in some kind of box?

No, but as per above, needs to be in a controlled drain situation.

If the filler cap is merely the OEM one on the main fuel tank and the surge tank is filled only by way of fuel lines then 10.4.2 means I am not legally required to fully enclose (isolate) a surge tank if it's in the cabin, because it cannot "be filled from inside the trunk or passenger compartment".
Q: Is this correct?

Correct. That said, I would personally be containing the surge (and fuel) tank(s). But that's just me, and wanting to be well clear of any petrol risks (probably due to my background in competition car regulations).

Q: Legalities aside, if I were to enclose it in some kind of box as an added safety measure (this would seem sensible in case of a leak etc) are you able to point me at a relevant specification please? Or does the interpretation of "fuel resistant and vapour-proof bulkhead" (diagrams 10.1 and 1.2) rest with the certifier?

It is over to the certifier to establish if a container is fuel resistant, and vapour proof. However there's nothing to stop you doing your research prior, so that you can present for example plastic material spec to the certifier. Motorsport people do this all the time (create enclosures) so maybe talk to some local to you motorsport competitors or fabricators, and ask what they've done.

Q: In a nutshell, if I were to mount a surge tank and pump in the cabin, do they need to be fully enclosed in a box to isolate them from the cabin? As far as I can tell by reading the regs, the answer would seem to be "legally, no.. but it would be a sensible move".

You are correct on both counts there. Legally no, personally, I would.

Q: The engine bay has no floor. A surge tank mounted in the engine bay is therefore not "located on top of the floor surface". Is this correct?
I ask, in case I have misunderstood the definition of "floor surface" or something. For example it doesn't refer to some imaginary line drawn through the car from end to end, does it?

You are correct, we're talking a surface on which petrol can accumulate. Which is why we include in that general discussion, ute trays, as they are a surface in which petrol might pool.

Q: Does this mean it is OK to fit a surge tank and fuel pump in the engine bay? No isolating panel required? For example if the surge tank and pump are located away from the exhaust and not above it or any electrics, is the engine bay legally an ok place to fit them? Please confirm.

That is correct. The usual level of caution would apply to petrol, and hot things, just like fuel lines / filters / fuel bowls etc.

Q: Can I fit a surge tank & fuel pump in the cabin, with a line in the cabin going from surge tank to pump as long as it meets the requirements of 10.8.5 (a) (b) and (c), and with the other lines going directly to bulkhead fittings like this one: www.aeroflowperformance.com/fittings/bulkhead-fittings/bulkhead-an/af832-10

Assuming I am understanding your correctly, then yes.

NB: If you're building a car that is going to be used in MotorSport NZ permitted events, then please apply their regulations. Otherwise you will end up with a certified car, that can't be raced.
www.motorsport.org.nz/sites/default/files/motorsport/manual/Live%2035%20App%202.01%20Sch%20A_0.pdf

[charlie]

Awesome Leon, thank you very much for such clear and easy to follow advice. Much appreciated!

[charlie]

Hi again Leon

What are the rules regards fitting an in-tank surge tank?

There doesn't appear to be a mention of such a system, so I can only assume the following:

1) a mod to an OEM tank requires certification

2) the modded OEM tank will need to meet the same standards as any other certifiable fuel system

First can we consider a commercially available in-tank surge tank such as the Aeromotive Phantom?

www.aeromotiveinc.com/phantom/

I'm guessing fitment of this will require certification?

If so, can the fuel tank be taken to a certifier for that purpose or does the entire vehicle need to be taken in for certification?

If for example the fuel tank is in the central tunnel of the car (such as an MR2) and fitment of an in-tank surge tank cannot be inspected once the OEM tank is re-fitted to the vehicle, would the revised fuel tank system need to be inspected prior to fitment and the vehicle inspected after fitment as well?

What about a custom in-tank surge tank made here in NZ?

For example if a conventional surge tank were dropped into an OEM tank in the same kind of way (cut a hole in the top of the OEM tank and fit the surge tank into the hole using a fuel proof seal) I'm guessing that require certification but are there any particular things to consider?  Eg I'm guessing that any welding / cutting / fitment of blots etc to the OEM tank may require coating with an anti-corrosive treatment...  Are there any other things to consider, peculiar to this idea?

This kind of system would use the OEM fuel pump to feed the in-tank surge tank. The surge tank would have a high volume fuel pump inside it (eg Bosch 044) with a fuel line (braided reinforced flexible type) running to the adjustable fuel pressure regulator and fuel rail. The return from the in-tank surge tank would simply be an overflow back to the main tank that it sits within (eg a baffled hole at the top front of the surge tank).

As long as the fitment of this in-tank surge tank was sound, such a system would be the safest possible arrangement for a mid-engined vehicle like an MR2. I say this because if a mid-engined car such as an MR2 leaves the road / track out of control, it will usually do so traveling backwards because of the greater weight in the rear of the vehicle. This means that hitting the armco could result in a ruptured surge tank if it were fitted in the boot.

By contrast, the OEM tank is inside the central tunnel of the vehicle and cannot be hit without the car being cut in half (in which case the occupants are already dead). It is also isolated from the cabin, isolated from the engine, exhaust, wiring etc, by the chassis tunnel in which it sits, and is "below the floor" of the car, thus ideally placed should a leak ever occur. Therefore an in-tank surge tank would be by far the safest arrangement for such a vehicle.

Because I don't see any direct mention of an in-tank surge tank in the NZ regulations, I'd be most interested in clarification regards the legal requirements. Please add any further considerations as necessary.

Thank you. =)

[Leon]

Good morning,

From the HCTM

10.1.3
A fuel tank fitted to a low volume vehicle that is constructed from
materials specified in 10.1.1 may be modified, provided that the
strength of the tank is not reduced.

10.1.1 notes
If using ‘electro-galv’,
the tank should be
sealed internally with a
proper fuel tank sealant
after welding to prevent
corrosion of weld joints.

So yes, you can fit an in tank surge tank as per the Phantom link.

From looking at the modification threshold in the VIRM
vehicleinspection.nzta.govt.nz/virms/in-service-wof-and-cof/general/miscellaneous-items/fuel-system
this modification by itself would not cause a vehicle to require certification, but if the vehicle was being certified for other items (eg: changed brakes, changed engine etc) then as a part of the certification of the whole vehicle, that modification would need to meet the LVV requirement.

For specialist information on tank construction or modification, I think you would be best to contact a fuel tank construction specialist, and supply them the LVV requirements. They are going to be a far more expert source of construction knowledge than myself.

Yes, if the modification is going to be hidden / difficult to access for a certifier, as with any component in this situation, arrange with the certifier to inspect the component before fitment.

[charlie]

Awesome, thanks Leon. Much appreciated! =)