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Quick question 8mm microbore size?

  1. Is 8mm the internal or external measurement?

  1. What is the other measurement?

- Just thinking this might be suitable for use as the oil feed to my waste oil burner, down from the tank.

Reply to
Harry Bloomfield
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Outside is 8mm . By other measurement I presume you mean the internal bore . Not sure what that is .Not much less I'd think If you want a sample e-mail me your details and I'll post a piece to you

Reply to
Usenet Nutter

In article , Harry Bloomfield writes

That's external (same as for 15, 22 and so on), wall thickness is 0.7mm, the rest is up to you :-)

Reply to
fred

Thanks for the offer, but it sounds perfect for the job. Call it (guess) 0.5mm wall - so around 7mm ID. They suggest 1/4" pipe, which is OD which seems to small to allow gravity flow if the oil is thick and I could not think where I might source fittings for it. By contrast, Microbore seems to have a quite a good range of fittings.

Reply to
Harry Bloomfield

fred used his keyboard to write :

6.6mm ID then - TA!
Reply to
Harry Bloomfield

If you change your mind let me know and of course you can get 10mm as well...I can send a sample of that as well if you need it ....It's plastic coated but that can be cut off. loads of fittings ..Try B.E.S.

Reply to
Usenet Nutter

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If you want smaller, copper brake pipe (slightly less than 5mm o.d) and fittings are available.

Cic.

Reply to
Cicero

Cicero presented the following explanation :

Thanks - I have some, and I think it will be too small/easily blocked. The microbore sounds about right for the job.

Reply to
Harry Bloomfield

In article , Harry Bloomfield writes

That's no use, you'll need to strain the chip fat before you put it in the tank.

Are you going to protect it in any way? I don't use oil so have no idea what bore is right or if protection is required/recommended but it sounds like a good idea.

Reply to
fred

fred formulated the question :

I did plan to strain what ever oil I could get hold of, at the moment all I have got is a local source for used cooking oil. Basically it will be some sort of tank on the roof, pipe down and inside, on/off valve, needle valve, then finally down into the stove. It is suggested to put a restriction/jet on the pipe end. The smallest passage will be through the needle valve/flow control.

Protect it from what?

As a alternative fuel I was thinking timber off-cuts, but the local joiners shops seem to burn these, but have lots of free wood shavings and sawdust. I was thinking it might be possible to perhaps compact these into a sort of log, using pressure and a little water.

Reply to
Harry Bloomfield

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It looks as if the 1/4" o.d is really only needed for the pre-heater so any larger size pipe connected to the 1/4" with a reducer will do for the main feed pipe in which case the larger the better. Larger will make filtering easier but anything larger than 1/4" close to the burner might need a flow controller of some kind once the preheater has warmed up.

Cic.

Reply to
Cicero

In article , Harry Bloomfield writes

Sorry, I should have added a smiley, I wasn't suggesting a serious flaw.

Impact really, with a gravity tank it would be at least messy if the pipe was damaged without noticing it, at worst there are fire or soil contamination issues. Just a thought.

Reply to
fred

It happens that Cicero formulated :

Another version (linked to from the Mother Earth site), which is supposed to improve on the original - suggests that pre-warming is not necessary and does cause control problems. The hotter the oil gets the more freely it runs, you turn it down and then it turns down too far. Without the pre-heating, room temperature supplied oil means there is no positive feedback into the control.

The improvement also suggests an alternative design for the actual burner dish, an aluminium disc which is dished saucer shape - so the oil pools in the centre if turned down and expands out when turned up.

That version also used an in-line filter for crud and water.

I could always drop down to copper brake pipe where it enters the burner.

8mm might also mean an 8mm radiator TRV could be used to control the oil flow, providing it could be prevented from cutting the oil supply completely off. Someone else has used a solenoid valve, connected to a room thermostat to control the heat output.
Reply to
Harry Bloomfield

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It looks as if you've got plenty of scope for experiment. I think the whole thing could become dangerous unless there is some positive means of restricting the oil flow, whether or not you use the pre-heater idea. I guess the pre-heater will only have very limited effect in any case as it won't seriously affect the main flow from the tank. The original article seems to suggest that the main benefit is to give a clean burn.

I'm not sure how well the TRV would work - it might not be sensitive enough to give any real control because of the variation in the oil viscosity. You could have a manually set valve to give a measured flow at average temperatures; the article suggests burning two pints an hour so you could set that as maximum at the highest expected temperature.

Cic.

================================================= Using Ubuntu Linux Windows shown the door =================================================

Reply to
Cicero

Cicero explained on 20/01/2010 :

Perhaps a disk with a hole drilled in it to limit the max flow rate.

I have an idea to add a twisted strip of steel in the air intake tube. The idea being to cause the burning gases to swirl around inside the stove, improve the gas/air mixing and improve the burn that way.

Certain commercial operations burning things which produce lots of smoke, sometimes use a secondary chamber burning a small amount of a cleaner fuel, to clean up the burn. Very effective they are, I know of such a system within spitting distance of the Houses of Parliament.

I think the biggest concern might be that of flame failure, where the oil keeps on flowing and makes a mess.

Definitely worth a trial though :-)

Maybe three valves in the line then?

  1. Max flow limiter
  2. On/off
  3. Needle flow control valve

All good interesting fun :-)

Reply to
Harry Bloomfield

fred was thinking very hard :

I have in mind a small 'header' tank, maybe one or two gallons. I fancy that even that small amount would keep me going for months.

Reply to
Harry Bloomfield

Fittings for 1/4" are easily available. It is used a lot for instrument and air lines for industrial/chemical plant control systems. Available in copper (brass fittings) or horrendously expensive stainless-steel (think £20 for a compression elbow - but it will be suitable for 10,000 psi!).

SteveW

Reply to
Steve Walker

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Plenty to think about. It occurred to me that the operation of the TRV might suffer from some hydraulic effect if the oil viscosity is much higher than plain water. Still worth a try and it's the only real way to find out.

Flame failure and resultant possible oil spillage might be overcome by a drain hole at the lowest point of the burner with a pipe leading to an outside sump to collect the oil for re-use.

Have you worked out how you're going to light, and re-light the burner automatically? It might be safer (and much easier) to consider the burner as an 'attended' heater which you only switch on and off at specific times.

Cic.

Reply to
Cicero

Cicero presented the following explanation :

It is only intended as an attended unit. It takes a some effort to light them I understand. The burner tray (of whatever design) needs to be got hot enough first, so that the dripping oil almost vaporises.

Quick update...

I managed to get some 8mm microbore copper from Plumb Center, some neat handle operated valves from Thorite (PC had none at all) and a ready made 3" diameter length of steel tube from a scrap yard - for the air down to the burner tube.

Reply to
Harry Bloomfield

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You're a brave man visiting scrap yards in this weather but getting the various bits and pieces together is likely to be the most difficult part of your project.

If you need any fittings for your microbore check out Toolstation as they seem to have the best range of fittings in all sizes and types.

Best of luck with the project - I'll look out for pictures when it's finished.

Cic.

Reply to
Cicero

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