quote:

Don't think I would exactly call it a "metering" pump in your configuration, "feed" pump would more fit it's function, I think. I assume you are intending to use this pump to pressurize a needle valve for dfip feed.

Tim, Actually I want a "metering pump" to try out on my Siphon nozzle AFG burner running on WVO. Currently it is using a "constant level day tank" about 12" higher than the nozzle to give me the flame size needed by the furnace. It has been working quite well but I want it to work better. Currently it requires the nozzle and adapter to be cleaned at around 120 to 150 hours of burn time. The nozzle and adapter slowly clogs due to polymerized VO build-up and the flame size (heat output) slowly drops. I am hoping a metering pump will be less sensitive to clogging and deliver a more constanr flame. I have 700 hours on the burner so far heating with 100% WVO.

I'd also use the "metering pump" on the drip stove which I will build at some point. I am thinking of one for a van used for winter camping. What do you think of using soapstone? It'd be hexagon shaped, approx 12" wide 20" tall. It'd be made from 8 pieces, 6 for the sides, 2 for top and bottom. The sides will be joined with high temp cement and screws. I wonder if that will work without cracking? The top and bottom will be removalble. There will be a small high temp glass window to light the stove and monitor the flame but the bowl will be removed by removing the top. The soapsone will absorb and release heat for hours after burner shutdown for the night. What do you think? Am I nuts? Any ideas and suggestions welcome.

Legal -- If you are not intending to electronically control the pump speed I guess the bypass valve would work just fine, don't see any reason why it woulden't but it may be a bit tough to regulate the flow to the burner as both the burner drip tube and the return to the tank are open headed, don't know just how the flow would know just where you wanted it to go unless you added a bit of a restriction to the burner feed line, would take a bit of testing.

Another approach would simply be to run the pump at speed to make some low pressure like 25 pounds, and use the normal needle valve approach. From reading about the use of the needle valve, and from the experiance of another fellow locally, the control of the fuel feed is pretty limited, one turn of the needle can change the feed from none to max, I would suspect that using a ball valve would be extremely difficult to do very fine control of the flow rate. Using the wiper motor I can control the flow reliably and repeatably down to as small a change as .01 G/H with no problem.

My oil supply tanks are located on the floor within a couple feet of the heater so the oil stays up around 100 deg f or more as long as the stove is burning. These tanks are made from 5 gallon propane tanks (my big collection funnels)(considering going to full sized 100 pound propane tanks and get several days heat for each filling). The pump is screwed directly on to the 3/4 inch pipe fitting on what is now the bottom of the tank using a reducer to 1/4 inch pipe, a 2 inch long 1/4 inch pipe nipple screws directly into the top of the pump. The pump stays flooded at a pressure of from 1/2 pound up to around 2 pounds depending on how full the tank is.

Canola -- OK - From what I have read you can get greater control over the fuel flow through a normal modern syphon nozzle if the fuel flow pressure can be controled from a bit of a vacuum up to maybe 20 pounds. I don't know if the fuel flow would help with the clogging, sort of dought it because of how the air and fuel are mixed inside the nozzle body of these nozzles that are designed for thin oil, that is why I had hoped the much more crude oil-o-matic nozzle design would not clog as much, still don't know. This clogging problem is almost always mentioned when burning heavy oil using a ligh-oil nozzle, about the cleanest syphon type nozzle design I have read about are the ones using steam rather than air as Fatty has mentioned he uses in his steam boat. Reading about big heavy-fuel boilers (huge building heating boilers, industrial process boilers, ship boilers) always seem to use the steam type nozzles.

Soapstone -- It does hold and release heat extremely well but I think it also will suck up liquid, not sure about this. A drip stove will eventually have some oil spilled, they also produce a bit of creasote that collects on the inside of the burner tank, with low firing rates this slowly drips down the tank wall and collects in the ash in the bottom of the tank (it burns away with high firing rates), makes something like very sticky asphault, fun to clean out of the tank.

For the first stove of this type I think I would use a small steel tank of some sort for the actual burner tank, then cover the outside with slabs of soapstone, a lot less likely to trash the stone, and I suspect it would look and work just as good.

Thanks Tim;

With the tank on the floor does the pump have to get the oil all the way up to the vent pipe and then down to the burner ? Wouldn' it be simpler to have the tank and pump elevated at about the same height as the furnace head ?

Yes, the pump moves oil out of the bottom of the tank and pushes it up a piece of 1/4 inch steel brake line to the combustion air intake tube, the oil then gravity flows downward til it drips into the burner bowl, the gravity flow is about half the distance that the oil is being lifted by the pump, this should produce a bit of syphon suction on the fuel line from the pump and reduce the pump's workload even less than the small amount of work it has to do in lifting the weight of the 1/4 inch diameter columb of oil up the feed tube.

There is almost no restriction in the fuel supply line so the pump is not working hard to make pressure, maybe takes 3-4 pounds pressure to lift the oil up to the intake point, the drip end of the fuel tube is only restricted down to 1/8 inch so this fuel tube is basically open headed, the only work the pump has to do is to lift the weight of the oil itself about 3 ft. I don't see any practical advantage of placing the tank and pump any higher up. Placing the top of the tank higher would also require that I lift the 5 gallon fuel supply cans higher to pour them in the tank.

Wiper motor low voltage stall problem -- I realized today that I may be able to eliminate this problem without using anything more than a simple switch. Wiper motors almost always have seperate low speed and a high speed connections, all my testing has been using the "high speed" connection. The motors run about half as fast from the low speed connection, if I use this low speed connection when metering the lowest fuel rates the voltage applied to the motor should be about twice that for the same speed using the high speed connection. From opening up wiper motors some years ago I think the low speed connection is actually powering a seperate, or at least a seperate part, of the internal winding and not simply adding a resister in series with the same winding as is used for the high speed. If it is accually powering a seperate winding the higher voltage needed to turn the motor should also equate to higher torque from the motor. This would allow using a simple selector switch between the speed control and the motor to select for high or low fuel feed ranges.

The temps are now back below freezing so the motor is being powered by at least 3 volts on the high speed connection, the motor only stalles if this voltage is lower than 3 volts so no problem with stalling just now. Once the temps get back up in the warmer range I will switch to the low speed connection and test if this idea will actually eliminate the stalling problem at low fuel rates.

Been snooping through my bookmarks and though this one would be useful :Discover Valves. All kinds of needle valves, the SS ones have viton O-rings too.

Now that the weather is a bit warmer I have been burning the single bowl heater at very low fuel rates, as low as .08 G/H (outer burner tank temp is only 125 deg f at this fuel rate). These low fuel rates amount to only 2-4 drops/second being fed to the vaporizing bowl, with these small flows the oil needs to be VERY dry, about any water at all in the oil will likely cause the burner flame to go out. I had one 5 gallon can of oil give me fitts, it did not seem to contain that much water but I could not keep the burner lit until I drained all this oil from the system, new dry oil burned fine.

If you're trying to run a wiper moter pump at very low speeds, but having trouble with stalling at low voltage, why not use a wiper delay circuit and normal voltage?
Cheers,
JohnO

A better solution to run a wiper motor at low speed is with a PWM (pulse width modulation) controller, speaking of which I have 2 extras for sale (I bought 4 keeping 2) One is a kit that's been built and tested and the other is the same but needs assembly. If anyone needs one send me a PM. They are good to 20 A if the MOSFET is heatsinked.

Guys this is fantastic and i have learnt a lot. We live in Australia and am going to use a modified version of the Senders approach to heat hot water that we pump through PEX tubing in our slab.

One thing you might want to look at Tim - a small Microprocessor called the Picaxe, programmed in Basic, the baby in the family support PWM for servo motor control and ALSO has a digital temp sensor (Dallas DS18B20) so you can provide your feedback loop.

Move up a bit in the family to the 14M and you could drive a cheap LCD and some buttons to set and monitor the temp control - this is the heart of the controls for my system - i am going to try using WMO in the Sanders style unit to heat hot water rather than my Natural Gas burner

Go to www.rev-ed.co.uk/picaxe for the all the info on these amazing chips

regards

CraigPicaxe Micros

Yes, a small processor will allow all sorts of control. I use solid state temp sensors and generally use Microchip PIC processors, a ton of models to select from and the programming language is the same for all (almost anyway, some devices have special functions).

This last winter's testing was pretty basic just to see what worked with the burner. The drip burner kept me warm all winter with only a small amount of agrivation, I had the flame go out a couple times and I did not have any safty to shut down the fuel feed. had a bucket under the overflow outlet so all the fuel was contained. If I had installed even a simple click-type Clixon style thermostat to shut the pump off once the temp dropped on the burner tank this overflow problem could have been eliminated, could even have rang an alarm bell to indicate the flame had gone out. The other agrivation was with the fuel pumps I used, these are "J"model suntec fueloil pumps, they have an internal gear profile that jambs up easily, the Suntec model "A" pumps use a gear style that should be much less prone to jamming, bought one of these "A" pumps off ebay this week so I can now do some testing to verify this.

I found information describing a reliable small Babington style pressure burner (commercial babington burner info here), there is a link at the beginning of that discussion back to another group of postings giving a bit of general info describing how to convert a standard pressure style oil burner unit into a small reliable Babingtom burner. I hope to test this babington type burner conversion over this summer, if it works I will make up a control system for this burner rather than the drip burner. The babington burns absolutely clean and can burn any type oil, the drip burner is smoky no matter what oil you are burning, less with diesel, a LOT more when burning used motor oil, veg is in between.

Tim,

Yep the PICs are good but yo9u have program in C or assembler and have the associated hardware to download. The beauty of the Picaxe is that they support basic and in ciruit downloading of programs.

Yes i have started reading about Babingtons too - my unit is going to be located outside as it is only used for heating water so i am not to worried about smoke (as long as the neighbours do not complain !). May move into Babingtons next year and work out a way to marry it to a water heating system.

Craig

Tim, to turn off the pump if the fire goes out, you could use a simple snap disc thermostat. Get one that opens the circiut when the temp falls below a certain point. You'd have to bypass it until the stove was up to temp, then flip a switch to direct the pumps power feed through the snap disk.

All the best.

Well - It's heater time again -- Over the summer I have been testing the idea of using the Suntec pumps as vehicle fuel lift pumps, I have developed several modifications for the pumps for this use (discussion here), some of these mods also apply here when using them as metering pumps.

Suntec "A" model pumps need to have a wierd internal diaphragm valve removed, no big thing, just take out the parts, also need to tap and plug two small holes with setscrews, and drill a 1/4 inch hole to allow oil to bypass the very thin internal passageway used to feed the oil into the suction side of the gears. You also need to either remove the internal oil strainer completely or replace it with a much courser one made for pumping used engine oil. The engine oil strainers are available from patriotsupply.com for about $5.00.

The "J" model pumps only need the hole drilled and the internal strainer changes. The following picture is of the "J" model pump and it's wiper motor.This is the setup used with this Sanders-style heater that heats the house.

house_heater_pump.JPG (63 KB, 101 downloads)

This picture shows the pump opened up so you can see the wierd factory triangular-shaped oil feed passage .

pump_open-oil_passage_visable_-_reduced_and_tweeked.JPG (79 KB, 86 downloads)

This picture shows the gearset layer. You can see the flat profile of the gear teeth, this makes these "J" pumps jamb up pretty easily if a chunk of something hard gets into the gears.

gear_set_visable_in_place_in_pump-resized_and_tweeked____.jpg (38 KB, 63 downloads)

This picture shows the new 1/4 inch hole drilled in the gear cover to allow the oil to have direct access to the suction side of the gears.

assembled_pump_showing_new_hole_-_resized_and_tweeked__.jpg (58 KB, 66 downloads)

This shows the inside side of the gear cover layer. The crescent-shaped piece fits between the inner and outer gear, oil is carried along both faces of this. The hole is drilled at the suction end of this crescent. The hole straddles across both sides of the sharp end of the crescent and is placed directly at the end of the crescent. The center of the hole is just a bit over 1/8 inch from the end of the crescent and directly in line with the center of the sharp end.

crescent_-_closeup_-_resized_and_tweeked.JPG (12 KB, 53 downloads)

This shows a reusable cover gasket that I made up from 1/16 inch thick teflon sheet gasket. I had the cover off a LOT last winter due to fat clogging the factory oil passage and from the original fine fueloil screen clogging on oil that had only been settled but not filtered. I hope the new fuel-feed hole, plus the addition of a bit of electric heat to both the fuel supply tank and the pump cover, eliminates the solidified fat clogging, the less restrictive used motor oil strainer should also not clog as much. I still expect I will have to pull the cover a few times so the reusable gasket makes this much easier.

teflon_gasket_-_resized_and_tweeked.JPG (80 KB, 47 downloads)

I also sanded the outer side of the pump cover totally flat, this is an attempt to get the best heat transfer from the resistive heater plate that I am making up, the plate will fit against the cover with a bit of thermal heat transfer grease between it and the cover. The heater will be 10-12 watts, not a lot of heat but should keep the pump above 80 deg f after an hour or two, have to try it to know for sure.

sanded_flat_cover_on_pump_-_resized_and_tweeked.JPG (73 KB, 52 downloads)