Single Pump Valveless

For discussing the modifications needed for diesel vehicles to run with 2 tank veggie oil conversions.

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Single Pump Valveless

Postby Burbarian » Wed Mar 19, 2008 7:36 pm

Have been designing this for my own conversion. Not entirely valveless, as it uses 4 checkvalves, but no manual, or 3-way valves. Already submitted to the USPTO when I couldn't find something similar in my research.

This design uses a compact reversible gear or vane pump coupled to a bidirectional electric motor. The motor is controlled by a thermocouple switched relay with an aux bypass switch.

Startup:
Image
On startup, the system runs on diesel. Fuel is pulled from instead of pushed through the filter in order to prevent premature wear on the pump. If you push through a filter, then that means the pump is driving unfiltered fuel, and whatever crud is in there that you hope to catch with the filter.

The direction of rotation automatically selects the fuel source and destination. On startup, it is diesel, which is pulled through the lower right check valve, and exits via the upper left check valve. D2 is supplied to an FPHE, then to the IP. Excess diesel overflow from the IP is routed back to the veg fuel filter. The overflow cannot re-enter in a loop through the upper right check valve as the check valve outlet is held shut by pressure from the pump.

The heated overflow d2 heats the vo filter from the inside-out, blending with the vo and backflushing the filter. This will help thin the vo from the inside while the engine coolant is still gaining temperature and heating the vo filter from the outside via a filter wrap.


Switch:
Image
On switching, the motor reverses direction, and the pump is now drawing from the upper right check valve.

This draws the previous overflow d2, followed by the thinned blend in the vo filter, followed by HIH heated straight vo from the tank, in that order. The transition of fuel type is gradual, and hence the lift pump will never have to contend with trying to start while having cold or solidified vo in its guts. This should be easy on BOTH the lift pump and the IP.

Fuel is sent out via the lower left check valve, to the FPHE, then the IP. Overflow from the IP is automatically looped, lowering the vacuum draw on the pump and hence making life easier for the electric motor even though it is now pumping thicker vo instead of thin d2.


Purge:
Image
On purge, the motor goes back to rotating counterclockwise. It is now drawing from the lower right check valve, and goes out via the upper left. The d2 will purge the FPHE and IP, and the hot vo is sent back to the vo filter. Again, this backflushes the filter for free.

Since both fuels pass through the FPHE, the purge diesel will not induce thermal shock. The d2 will have 1% to 2% vo as a lubricity enhancer to prevent lack-of-lubricity failure of the IP from hot d2. Lubed d2 should also be kinder to the lift pump than straight hot thin d2 on a purge. And since the lift pump stops while being full of d2, you don't have to contend with cold vo in the vo pump on startup. The d2 and vo pump is one and the same.

No return line needed for either fuel tank.

When running on d2 alone, the vo tank will gradually fill with the overflow, so just switch when appropriate.

For priming, a 'T' air purge plug can be inserted between the FPHE and the IP. This minimizes the amount of air bubbles entering the IP. Just crack the plug when priming.

Comments and criticism most welcome.
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Postby SunWizard » Wed Mar 19, 2008 8:10 pm

Very innovative ideas, it makes for a very simple rig. I like not having any solenoid valves to stick and 1 pump.

One problem I see is the amount of diesel that would be going back to the VO tank during warm up. For example, on my truck the pump puts out 30-60gph to exceed the highest demand needed, when using less than that like a typical 3gph, 27-57gph is returning. This means in the 5 minutes of warmup you could get 5 gallons of diesel in the VO tank. Maybe you could solve that by making the pump variable speed and vary it with engine RPMs?

I don't like backflushing filters. Filters are designed for flow in only 1 direction, and most have steel support screens on 1 side for that. Maybe you could find one supported both ways. And any concentrated crud built up on the filter gets blown back and accumulates in the tank and lines instead of staying put until the filter needs changed.

At startup and purge, if the filter is getting clogged a little, there will be back pressure which may easily exceed the pop pressure of the check valve and you would have looped flow at all times. Maybe thats not a bad thing, you could change the design to always loop and it solves the above 2 issues I brought up.
YVORMV - Your veg. oil results may vary.
95 Dodge Cummins 4x4 SVO WVO conversion.
81 Mercedes 300D- stock and happy on V80/D20 blend.
Low fossil net zero house- 100% solar power and heat.
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Postby Burbarian » Wed Mar 19, 2008 8:45 pm

SunWizard wrote:One problem I see is the amount of diesel that would be going back to the VO tank during warm up.


Excellent point. I had my senile neurons stuck in thinking of a full hydronic preheat, and the use of a high pressure low volume hydraulic powerpack pump. Good suggestion on the variable speed motor. I had designed it with bidirectional back-emf suppression diodes for rapid braking and direction switching without inducing a spike load on the motor. Just a pair of diodes on the NC/NO contacts with the moving contacts connected to the motor and a short delay before power is reapplied.

I don't like backflushing filters. Filters are designed for flow in only 1 direction, and most have steel support screens on 1 side for that. Maybe you could find one supported both ways.


Had Caterpillar 3304 fuel filters in mind (Wix 33360, what I use in the bulldozer). They are cartridge full metal canister fuel filters, and are often backflushed in the boonies to make them last longer. I figured the primary purpose of backflush in this scenario was to unclog the filter of cold vo with hot d2, and to produce a switchover-friendly fuel transition.

At startup and purge, if the filter is getting clogged a little, there will be back pressure which may easily exceed the pop pressure of the check valve and you would have looped flow at all times. Maybe thats not a bad thing, you could change the design to always loop and it solves the above 2 issues I brought up.


Fantastic. I'd throw in another two checkvalves on the overflow, and the fuel will preferentially loop towards the pump inlet, whichever it may be, while preventing cross contamination. You'd not get the rapid vo filter thawing and blend, but 2 check valves should be simpler, cheaper and more foolproof than a freq-drive synchronous motor and driver.

Edit: For a so-called 'valveless' design, it sure does use a lot of check valves.. With one on the outlet of the D2 filter, it will prevent contamination of the d2 supply by vo even with a plugging vo filter causing backpressure. I'm machining my own check valves in an integrated pump manifold with the fuel filters plugging right into it. No hoses or clamps or fittings to mess around with. It will be easy enough to add a few more direction control check valves into the design and address all the issues you kindly brought up.

Excellent critique. The best kind. :D
Last edited by Burbarian on Wed Mar 19, 2008 9:33 pm, edited 1 time in total.
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Postby SunWizard » Wed Mar 19, 2008 9:32 pm

Use a gear pump they are much better than vane pumps for veg.
YVORMV - Your veg. oil results may vary.
95 Dodge Cummins 4x4 SVO WVO conversion.
81 Mercedes 300D- stock and happy on V80/D20 blend.
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Postby zoochy » Thu Mar 20, 2008 12:28 am

You might consider moving your heat exchanger so it does not heat your diesel. Hot diesel is hard on the IP.

Image
91 Toyota Hiace 3L engine w/ a 300W ½” heated fuel line, lift pump, additional 10um fuel filter, and a 2nd diesel tank for starting.
>160,000 km on:
88% canola WVO
11% old gasoline
.6% turpentine
.3% acetone
.1% eye of newt
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Postby Burbarian » Thu Mar 20, 2008 2:06 am

zoochy wrote:You might consider moving your heat exchanger so it does not heat your diesel. Hot diesel is hard on the IP.


Hello Zoochy,

I definitely had the option of only routing the vo through the FPHE, but made the deliberate decision to run both d2 and vo through either the same or separate FPHEs. Hot diesel is hard on the IP due to lack of lubricity. As I explained in the original post, I will be blending 1% to 2% vo in with the starting d2 as a lubricity enhancer. Regular d2 is too 'dry'. ie lacks lubricity.

The heated d2 will preheat the IP and the injector lines. This is beneficial since I would prefer a hot IP to receive hot vo on switchover instead of a cold IP getting hot vo. Thermal shock. The relatively small amount of hot vo entering a cold IP will very rapidly lose its heat to the surrounding cold metal and become viscous, which could overtorque the rotor and cause it to snap in a rotary IP.

The design starts with cold d2, which gradually becomes warm, then hot d2, then on switchover becomes hot previously overflowed d2, then d2/vo blend, and finally, straight vo. A gradual transition, all at the same temperature.

Thank you for your input!
Last edited by Burbarian on Thu Mar 20, 2008 3:06 am, edited 1 time in total.
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Postby Welder » Thu Mar 20, 2008 5:18 am

Very creative, Burb!
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Postby FlyboyDVIII » Thu Mar 20, 2008 6:30 am

zoochy



Joined: 07 Mar 2008
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Posted: Thu Mar 20, 2008 1:28 am Post subject:

--------------------------------------------------------------------------------

You might consider moving your heat exchanger so it does not heat your diesel. Hot diesel is hard on the IP.
__------------------------------------------------------------------------------------

Hi Zoochy, last summer while returning from South Dakota 3479 miles round trip, pulling our 25' camper I had to use some diesel. An ugly reality to the trip being over 1200 miles more than planned. Being I have both a temp. and pressure gauges in my IPs feed line inches before the IP, I was amazed to see that while pulling the camper in July, my Dino fuel was entering the IP at over 155f on my temp gauge. This fuel was from the stock tanks, not heated in any way by veg heater, I actually had the heater hose clamped off to the veg system, no need heating it when the veg was gone.

What is your definition of "Hot Diesel"?
93, F250, 7.3, N/A, WVO since 5-06 over 147K so far, 2wd, ext cab, 100 gal. tank, DIY system. 10psi 23A FASS w/ ProComp regulator.

FilterFuge FF60 CF, over 22,300 gal. spun
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Postby SkySkiJason » Thu Mar 20, 2008 10:24 am

This design seems very prone to air leak problems. Not just the air from filter changes, but any little bits of air that enter the system during operation have no way out. The "(3) valve" systems that include a 'controlled VO loop' return diesel/VO to VO tank during purge and this would allow accumulated air a way out.

I also have concerns for the HOT diesel. Not sure if a couple % VO is adequate to compensate the for lack of lubricity. Are you basing this on some science/testing? You would never introduce 'cold' VO to your IP in a well designed system, so I'm following your logic there either.

I'm not a big fan of 'shared pumps', I guess I'm quite spoiled by the redundant fuel systems in my junk! Maybe a super-reliable pump would be the answer. On pumps, it is far easier (and more efficient) for a pump to push thru a filter than pull. The filtration required to ensure a long-life pump is far less than that required by IP and injectors. Where is this pre-pump contamination gonna come from?

All that said, I love the 'out of the box' thinking - GOOD WORK MAN! Sounds like I wish I had your resources too!

Best of luck - PLEASE keep us posted! :D
2001 F-350, DRW, 4x4, XLT Crew Cab, flat bed, 7.3, 6 spd, Dipricol Optix gauges, DP tunes - Single-Shot injectors! Vegistroke-style WVO conversion, 55,000 VO miles so far - 190 deg VO before the heads
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Postby SunWizard » Thu Mar 20, 2008 10:53 am

2% VO or biodiesel provides great lubricity. See research here:
http://www.burnveg.com/forum/viewtopic.php?t=39

And I agree with you about pushing through a filter being better. And less likely to get vacuum leaks around the filter gasket which is common on filters under vacuum, unless tightened with a breaker bar.
YVORMV - Your veg. oil results may vary.
95 Dodge Cummins 4x4 SVO WVO conversion.
81 Mercedes 300D- stock and happy on V80/D20 blend.
Low fossil net zero house- 100% solar power and heat.
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Postby SkySkiJason » Thu Mar 20, 2008 11:45 am

Don't many IP's dislike fuel temps over 180F?

It wouldn't take long to get diesel up to coolant temp w/a FPHE. Thin diesel heats up waaay faster than thick VO.

I'm not trying to perpetuate myths here, thats why I asked the question. :wink:
2001 F-350, DRW, 4x4, XLT Crew Cab, flat bed, 7.3, 6 spd, Dipricol Optix gauges, DP tunes - Single-Shot injectors! Vegistroke-style WVO conversion, 55,000 VO miles so far - 190 deg VO before the heads
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Postby Burbarian » Thu Mar 20, 2008 11:07 pm

SkySkiJason wrote:This design seems very prone to air leak problems. Not just the air from filter changes, but any little bits of air that enter the system during operation have no way out. The "(3) valve" systems that include a 'controlled VO loop' return diesel/VO to VO tank during purge and this would allow accumulated air a way out.


Excellent point. I'll stick in an automatic air purge valve just after the FPHE. It's basically a big 'T' fitting with the middle stem pointing up, to which a tube is attached with a cap. A small hole is drilled through the cap, and a stainless steel finned float is in the tube. (A rod with one end ground to a point and the other end drilled to form an air pocket, then plugged with a solid shaft and welded shut, trapping the air. The pointy tip points up) When pressurized fluid is flowing through the T, it will also go up the tube, lifting the float, which will plug the hole. Any air in the system is lighter than oil and will preferentially go up the 'T' into the tube, get past the fins and wind up just under the cap. As air accumulates in this pressurized system it is compressed. As more air builds up it will eventually lower the fluid level in the tube sufficiently such that the small pressure differential at the tiny orifice will no longer hold the weight of the no-longer-adequately-buoyed float, and the float will drop. Air jets out the tiny hole, the fluid level rises, the float rises, and plugs the hole again. It sounds just like pressing the trigger momentarily on an air blow gun. It's easy to fabricate with a lathe or even a bench top drill press.

I'm not a big fan of 'shared pumps', I guess I'm quite spoiled by the redundant fuel systems in my junk! Maybe a super-reliable pump would be the answer.


I'm planning to use a hydraulic power pack pump. Those things are like Welder's Frankenpump, designed for 3000psi and long abusive service in industrial settings. They come in gear and vane types. I figure either is ok, as I doubt heated vo will put up as much backpressure resistance at 50psi as a loaded hydraulic cylinder will at 3000psi. And of course I'll be running it slow in this application. However, I do agree completely with you. Redundancy is good. Triple redundancy with disparate means is golden. :)

On pumps, it is far easier (and more efficient) for a pump to push thru a filter than pull. The filtration required to ensure a long-life pump is far less than that required by IP and injectors. Where is this pre-pump contamination gonna come from?


My views are probably biased by my background. I did a lot of work in heavy industrial and mining equipment, and high pressure hydraulic pumps always have their filters on the suction side. The primary cause of damage to hydraulic pumps is contaminants that wind up in the hydraulic tank. In the field, things could fall in when changing the hydraulic fluid. Like nuts and bolts, twigs and bugs, etc. Granted that would be unlikely to happen in this specific application, so I am probably just exhibiting unreasonable paranoia from previous experience and hence this influences my design decisions.

SunWizard wrote:And I agree with you about pushing through a filter being better. And less likely to get vacuum leaks around the filter gasket which is common on filters under vacuum, unless tightened with a breaker bar.


For low pressure systems (<500psi) using flat cork gaskets in regular filter housings, you're absolutely right. Vehicular systems were designed for easy removal and replacement, specially with filters which are replaced frequently. In contrast, high pressure systems are almost always sealed with o-rings and d-rings, not felt or cork gaskets.

Thankfully, it is very easy to secure a filter against air leaks. A common trick with spin-on metal cannister hydraulic filters: don't use a filter base. Instead, just screw the filter central outlet to a hose fitting, and drop the entire filter into the hydraulic tank. The only way air will get into the system from vacuum in the filter is if you're running low on fuel. Which will happen to any system regardless of push or pull if you're down to sucking fumes... Of course, that's not really practical in a tight installation unlike with construction equipment, so I will be using a filter housing.

With cartridge filters (not spin-on) like the CAT filters I will be using, the housings are much better sealed and don't require a breaker bar. And any residual air leaks should be taken care of by the automatic bleeder.

SkySkiJason wrote:Don't many IP's dislike fuel temps over 180F?


Given clean dry fuel, the primary culprit remaining is lack of lubricity and degradation of the lubrication film at high heat. Given adequate lubricity additive, that should no longer be a concern. As well, I've run construction crews in Asia where water boils into steam when rain strikes the IP running straight d2. That's on the surface, so I surmise that the innards would be significantly hotter still. In that hot, humid and rainy environment, the only things that I have seen cause damage to the IP was wet and contaminated fuel.

This discussion has a quote from the IP manufacturer:
http://biodiesel.infopop.cc/eve/forums/ ... 8741018512

It is unsurprising, considering that diesel trucks operate in desert environments all the time on straight d2 without issue.

Thanks all for your insights and valuable comments! You have helped me tremendously.
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Postby SkySkiJason » Fri Mar 21, 2008 8:24 am

I can't wait to see it.

Thanks for your effort. Keep up the good work. :mrgreen:

I have one of those air bleed thingys on my hydronic heating system at home. Its a clever contraption, I gotta study your DIY version a little more, thats cool! :wink:
2001 F-350, DRW, 4x4, XLT Crew Cab, flat bed, 7.3, 6 spd, Dipricol Optix gauges, DP tunes - Single-Shot injectors! Vegistroke-style WVO conversion, 55,000 VO miles so far - 190 deg VO before the heads
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Neat Idea

Postby sanderlings » Tue Mar 25, 2008 6:39 am

Neat idea Burbarian. I was thinking (Now we are in trouble) about the closed loop on the diesel side increasing purge time.

"Fantastic. I'd throw in another two checkvalves on the overflow, and the fuel will preferentially loop towards the pump inlet, whichever it may be, while preventing cross contamination."

I ran a two pump system last year that had the return branched back upstream from each pump like you mentioned. Two checkvalves kept the return isolated to the drawing pump, just like you said. And to decrease purge time I teed into the return line and ran a purge line back to the WVO tank. This line had a small facet "purge pump" that pushed through a checkvalve with a higher crack pressure than the other two on the return. So during purge, I would turn on the purge pump and it would put the return line under vacuum (The checkvalves prevented it from drawing anything else) and draw the returning WVO off the loop and push it back to the WVO tank. It worked fine, and it was valveless (Electric anyway).
todd
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Postby Burbarian » Tue Mar 25, 2008 6:56 pm

Hello Sanderlings,

Neat idea on the purge pump. I have a small brick type pump from AutoZone that's been used in experiments lying around that might be retasked for that.

Here's the latest iteration, with yellow being flow direction and red being no-go.

Start/Purge/Stop:
Image
On startup the IP overflow (d2) is split into two branches, one going to the d2 inlet and the other going to the heated vo filter. The 2nd check valve has a higher breakover or crack pressure, so only a fraction of the d2 return goes to the vo side for backflushing. The vo pump inlet is held shut by the lift pump pressure to prevent pushing vo into the IP. One could also connect a pressure sensor right there at the 'T' to determine when the vo in the vo filter has melted due to a drop in backpressure. For most folks, that would be worthless, but for the poor schmucks running lard, it would be useful information. Most of the overflow is looped on the d2 side.

Note the upper and lower left check valves on the pump could also be moved to just after the FPHEs.

3 relays wired in series and controlled by engine temp, IP overflow temp, and vo overflow backpressure respectively, could automatically determine when it is safe to switchover, and automatically command the pump to go into vo mode. This prevents premature switching and takes care of the senility factor - forgetting to switch. Of course all fuel pumps must be wired through a dead-man relay that is controlled by an engine oil pressure sensor and/or overheat sensor. This will shut off the pump in the event of oil presure loss or coolant loss.

The fuel now goes through two independent small FPHEs instead of a single large one. This preheats the vo prior to injection and allows quick purge as on switchover to d2 the only vo one has to contend with is in the IP and lines, instead of having to flush an FPHE full of vo. This remaining vo is split to return-to-vo and to the d2 loop and is rapidly diluted and either consumed or backflushed through the vo filter.


VO mode:
Image
In vo mode, the IP overflow goes only to the vo inlet, as the d2 filter is protected by its own check valve. This prevents contamination of the d2 supply.

Note: Not indicated is the automatic air bleed device just prior to the IP as previously described. If there is significant interest, I can do a separate writeup on how to DIY your own automatic air bleeder.

I've been aiming for a design with minimum active components, in this case, only one, the primary pump. If one doesn't mind longer purge times, a single FPHE can be used. With Sanderling's purge pump idea, that would save me getting 2 FPHEs and just plumb in the spare cube pump for quick purge. Good idea! Nothing like retask-and-reuse of already available 'stuff'. :)

As always, comments and criticism gladly welcomed.
Last edited by Burbarian on Tue Mar 25, 2008 7:23 pm, edited 1 time in total.
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