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Author Topic: Silent Lister exhaust  (Read 18689 times)
KenB
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« Reply #15 on: May 21, 2010, 12:42:02 PM »

Mark,

If you are going to run any pipe 10m - make sure that it is at least 3" diameter - so as to avoid excessive back pressure. 

If you can dump the heat with an exhaust gas heat exchanger, (water cooled copper tube around the cast iron damper - suitably insulated with fibreglass) you could probably run a length of 76mm black plastic drainpipe down the centre of a length of 110mm soil pipe,  this would give you a reversal, plus additional expansion, plus the benefit of a buried pipe and the sound deadening properties of being underground.

You would probably want to tune the length of the exhaust so that is is not a wavelength multiple of the 850rpm (or whatever rpm) you are running the engine at.

I don't think perforating the outer pipe will help. You don't really want the exhaust byproducts leaching into the soil.

Run it under the vegetable plot and warm the soil!



Ken

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bottleveg
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« Reply #16 on: May 21, 2010, 01:47:13 PM »

Some underground versions here: http://www.navitron.org.uk/forum/index.php/topic,9775.0.html

I think you'd need to get more mass in the chimney walls to help with dampening, e.g. fill the breeze blocks with concrete.

Thanks for that link Stephen.
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bottleveg
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« Reply #17 on: May 21, 2010, 01:59:56 PM »

Mark,

If you are going to run any pipe 10m - make sure that it is at least 3" diameter - so as to avoid excessive back pressure. 

If you can dump the heat with an exhaust gas heat exchanger, (water cooled copper tube around the cast iron damper - suitably insulated with fibreglass) you could probably run a length of 76mm black plastic drainpipe down the centre of a length of 110mm soil pipe,  this would give you a reversal, plus additional expansion, plus the benefit of a buried pipe and the sound deadening properties of being underground.

You would probably want to tune the length of the exhaust so that is is not a wavelength multiple of the 850rpm (or whatever rpm) you are running the engine at.

I don't think perforating the outer pipe will help. You don't really want the exhaust byproducts leaching into the soil.

Run it under the vegetable plot and warm the soil!



Ken



 I was thinking 4Ē underground pipe and then 4Ē soil up the house wall and a birdcage on top.
Yes max. Revs. Is 850rpm. What do you mean by tuning a length of exhaust?
The cast iron damper only gets warm but the pipe going in and out gets hot. I could run 15mm copper around that and gravity feed into the water tank.
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jotec
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« Reply #18 on: May 21, 2010, 06:51:59 PM »

I like Kens idea.
I might try that myself on my engine. I am sure we could fix up a heat extractor on yours after if goes through the wall so that plastic pipe can be used. If using plastic it is easy to start long and cut bits of to quieten it down, go to far and add a joiner.
D ick
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bottleveg
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« Reply #19 on: May 21, 2010, 07:26:43 PM »

Hi D ick, I have tried 4Ē plastic on the end of the exhaust and it seems ok. I was thinking of wrapping annealed 15mm copper pipe around the exhaust before it goes into the damper.
How about this pipe-
http://www.drainageonline.co.uk/Land-Drainage/100mm-Perforated-Land-Drainage.htm
I was wondering if the corrugations would absorb more energy than smooth solid pipe. I guess it wonít be so good with heat?
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noelsquibb
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« Reply #20 on: May 21, 2010, 08:23:57 PM »

I'm using the corrugated perforated underground plastic silencer for my 4.5 kva diesel genny and its not anything like as quiet as Frots pit 'o doom but I reckon his little Kubota twin starts off a whole lot quieter than my Petter single.

The silencer pipe is about 9" deep and covered in gravel and it was already there, pretending to be a land drain.

When I first tried it, the covering gravel jumped up and down and a fair amount of noise was audible from the junction area. I shut it up a bit more with some conveyor belting and more gravel in this area.

Theres a manhole about 30m down the drain line and when I popped the lid and stuck my head in ( like you do ) there was no audible noise from the incoming pipe, even with the genny running.

Having burnt myself on the far end of bits of scaffold tube that Ive stuck over the silencer outlet in the past, I'm not convinced that the perforated corrugated land drain wont melt in the junction area but I have a length of steel pipe at the ready.  I know that BT duct goes soggy at 100c ..........

Then theres the foul sewer drainage system.
Usually nice and deep and any smells would be taken care of, with the mercury and cadmium deposits in the exhaust particulate blending in with the mercury and cadmium deposits of eeerrr ....

And you could watch the water in the bog pan to see if the genny was running.

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bottleveg
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« Reply #21 on: May 21, 2010, 09:27:39 PM »

I'm using the corrugated perforated underground plastic silencer for my 4.5 kva diesel genny and its not anything like as quiet as Frots pit 'o doom but I reckon his little Kubota twin starts off a whole lot quieter than my Petter single.

The silencer pipe is about 9" deep and covered in gravel and it was already there, pretending to be a land drain.

When I first tried it, the covering gravel jumped up and down and a fair amount of noise was audible from the junction area. I shut it up a bit more with some conveyor belting and more gravel in this area.

Theres a manhole about 30m down the drain line and when I popped the lid and stuck my head in ( like you do ) there was no audible noise from the incoming pipe, even with the genny running.

Having burnt myself on the far end of bits of scaffold tube that Ive stuck over the silencer outlet in the past, I'm not convinced that the perforated corrugated land drain wont melt in the junction area but I have a length of steel pipe at the ready.  I know that BT duct goes soggy at 100c ..........

Then theres the foul sewer drainage system.
Usually nice and deep and any smells would be taken care of, with the mercury and cadmium deposits in the exhaust particulate blending in with the mercury and cadmium deposits of eeerrr ....

And you could watch the water in the bog pan to see if the genny was running.



Well, funny you should mention a manhole-
I have manhole right where my exhaust exits the engine house. Iíve run the exhaust though a series of breezeblock ducts and then in to the top of the manhole. The result was mega quite. I did get some transmission through the clay pipe to the downstairs loo (4m run), so I could hear the engine in the loo but not when I went outside, and a slight shimmer on the water. I couldnít hear any noise and no fume when I removed the trap on the sink. Water vapour could be seen rising from the top of the soil pipe, like when the shower is running on a cold day.
My concern was that I might send fumes into my neighbourís property; I know this shouldnít happen if all is fixed, as it should be. I canít decide if the fume would sink in the sewer or rise. I think the gases are heavier than air.
The manhole is fairly large so I could construct another series of baffles inside and maybe remove the noise transmission. This would be my preferred design, as I know it works.
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noelsquibb
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« Reply #22 on: May 21, 2010, 10:41:46 PM »

Quote
Well, funny you should mention a manhole-

Yeah, ready made 'n gagging to be filled with noise and fume  whistlie

I reckon you should be ok, as all houses should have a high level soil vent pipe ( SVP) at the top end of their system and all connections into a foul drainage system will have a waterseal to ensure no stinky gases can enter the dwelling.

Methane is sometimes generated in sewers and is a heavy gas and carbon dioxide is a regular feature too. Hence the need for gas detectors for these gases ( plus oxygen levels ) as a minimum, for working in a foul manhole.

As your local sewage treatment plant gets a fair amount of what you are putting in by way of unburnt fuel and particulates, you are not really creating a new hazard. Dunno how it might effect the bugs in a digester / septic tank if you had a private sewage disposal system though. They like a bit of oxygen .......

I do have a bit of visible fume hanging around the exit of my land drain, a distance of approx 80m away, so the smoke is pushed along rather than venting through the perforations and up through the gravel.

Its going to have to be ever so quiet if you have neighbours though.
Unless they move cos of the strange smells ......
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insolare
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« Reply #23 on: May 21, 2010, 10:52:24 PM »

I just shuddered at the thought of you pushing exhaust fumes down the sewer. This is wrong on so many levels. Think about it. Faulty air admittance valves, dry traps in sinks that haven't been used in awhile, kitchen/bathroom refurbs with the sewer pipe left open, bad DIY ( washing machines plumbed with no trap - seen it), etc,etc.
I'd say it's just not worth a potential manslaughter charge.
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noelsquibb
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« Reply #24 on: May 21, 2010, 11:36:41 PM »

Yup good points insolare.
The cheerful assumption that no one would put up with drain smells is not entirely fail safe.

Also if there is a partial blockage downstream, that causes a water seal, then the heavier gases could build up and vent through any failed seals.

Not having had to share sewers with neighbours for the last 30 years has messed up my thinking.




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bottleveg
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« Reply #25 on: May 21, 2010, 11:52:00 PM »

Mmm. itís a difficult one! I know what you mean about open vents and traps.
 It seems a pity to completely abandon the idea because it was so effective; all I had was a very low hum like a small electric motor. This particular manhole services my neighbour and myself and then itís into the main sewer. I could fit a vent on the manhole so the fumes wouldnít travel any further.
I think what Iíll do is try it with the extra baffles in, remove some traps, and maybe the loo, from my place and next door, and see what comes out. If we get fumes then Iíll have to revert to creating my own manhole. Iíll give it some thought.
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bottleveg
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« Reply #26 on: May 23, 2010, 04:16:51 PM »

Interesting results! I reinstated my above ground maize and then built a second one inside the manhole, so the fumes/noise leave the steel exhaust, travel along a series of tunnels, with pieces of breezeblock set at odd angles, and then finally exits through a 3Ē hole into the manhole. Result, slight reverberations along the clay pipe to downstairs loo, fumes in the manhole, but, most surprisingly, absolutely no noise where the fumes came out of the maize.
Iím still not happy with the fumes in sewer but, inspired by these results, I will ether
isolate the maize outlet from the sewer and pipe the fumes along to a vertical soil stack or build another maize away from the manhole and pipe into it and then off to a soil stack.
Iím unsure on the merits of using dense concrete blocks. My original maize was built solely from breeze but my new one was capped with dense blocks ( at the point the exhaust entered). The original was very quite but the concrete increased the Ďboomí from the exhaust.
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Alan
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« Reply #27 on: May 23, 2010, 10:48:33 PM »


Quote ď This is wrong on so many levels. Think about it. Faulty air admittance valves, dry traps in sinks that haven't been used in awhile, kitchen/bathroom refurbs with the sewer pipe left open, bad DIY ( washing machines plumbed with no trap - seen it), etc,etc.
I'd say it's just not worth a potential manslaughter charge. ď

I would not leave a boiler with flue carbon monoxide concentrations above
100 parts per million.

Concentration that is immediately dangerous to life and health is 1200 p.p.m.

Old engines use a proportional air damper ( fixed single blade in the air path, below 25% and above 60% very little mixing takes place )  which means it can only be an efficient means of mixing the air to the fuel ratio when the damper is fully open. Typical readings of carbon monoxide would be.

4000 to 7000 parts per million when the engine is cold or the calorific value of the fuel has changed. ( calorific value of waste cooking oil variable depending on lots of factors )
Exposure to these concentrations means Death in 15 Ė 20 minutes

Modern engines use a variable orifice to match the required amount of air to the fuel ratio required. The mixing and turn down ratio is much better on this type of design.
With a catalytic converter. The carbon monoxide in the exhaust is converted to water vapour and carbon dioxide.
Even new design of engine with exhaust products down the sewer. ( Not for Me )

Regards

Alan
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bottleveg
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« Reply #28 on: May 24, 2010, 01:34:23 AM »

Thanks for that extra info Alan. Iím not happy with the fumes in sewer idea but at least it was a quick way for me to try out an idea. Iím going for an underground maze that is eventually vented above the roofline. I just need to decide between 3Ē or 4Ē pipe as the carrier after the maze.
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bottleveg
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« Reply #29 on: May 28, 2010, 09:41:49 AM »

Success. My final design has a breezeblock maze on the side of the engine house and another maze directly below but built inside the manhole. The fumes are then piped through the side of the manhole, in 68mm down pipe, up through a conifer hedge and into 110mm soil pipe. They then run 15m along the top of the hedge and exit from a gas cowl. The result is no noise at the end of the pipe.
Iíve managed to use the mass of the manhole but the fumes are isolated from the sewer. The only place I still have slight noise is where the exhaust leaves the engine house but I think a second skin of concrete around the breeze can eliminate this.
So far, so good!
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