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Author Topic: Lack of ooomph  (Read 4857 times)

SailorGreg

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Lack of ooomph
« on: November 05, 2014, 02:07:58 pm »

 I have been running my steam launch a couple of times recently (after a summer of little steam activity) and have run into an issue.  Previously, it took about 10 minutes to get to 40 psi from cold and then the boat would run happily for about half an hour.  Recently, raising steam seemed to take a little longer, then when I opened the regulator the pressure dropped to about 25 psi and continued to decline over about 10 minutes until it barely turned the engine.  Closing the regulator for 5 minutes lets the pressure build again, but then the same thing happens again.

I have checked the gas jet visually and it looks clear, there are no obvious leaks and the engine runs fine with compressed air at about 20 psi.

My knowledge of what to do is now exhausted  :embarrassed:.  Can anyone offer any more steps I can take to try and recover my boat's performance?  {:-{

Oh, it's a TVR1A and a Maccsteam 3.5" horizontal boiler with a Maccsteam gas tank - my build of the steam plant is here http://www.modelboatmayhem.co.uk/forum/index.php/topic,38966.0.html

All suggestions welcome.

Greg

pipercub1772

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Re: Lack of ooomph
« Reply #1 on: November 05, 2014, 03:07:00 pm »

Hi I would chq the gas tank is full ,take the gas jet out open the gas valve ,you should feel a good pressure coming out of the supply pipe ,if all ok suspect the gas jet,its happened t o me a few times ,try blowing from the front of the jet,i use a compressor but you could use a bycicle pump with some silicone tube on the end so not to damage the jet ,i have the same boiler as you and after a while i changed the no 5 jet to a no 8 jet and that improved performence also if the gas tank is being used in a cold enviroment you will find the pressure will drop of, try doing youre experiments indors or in a warm place ,i have started using a flask of hot water to fill the boiler it heats up a lot faster and when you refill the gas tank at the lake i poure a bit on the gas tank to warm it up a little ,hope this helps ,regards Allan
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flashtwo

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Re: Lack of ooomph
« Reply #2 on: November 05, 2014, 03:07:58 pm »

Hi Greg,

Is the chimney flue clear of obstructions like lagging?

Has soot built up on the heating surfaces? I've just carried out a "soot blow" on my coil boiler and most of the soot had been caused by the pilot flames.

Are there any cold spots along the gas pipe indicating throttling caused by a slight blockage - once I found a small blob of silver solder had worked its way down the pipe and the gas expansion after it caused a visible frosty spot.

Valve timing?

Ian
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Jerry C

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Re: Lack of ooomph
« Reply #3 on: November 05, 2014, 08:39:51 pm »

Greg, this has happened to me loads of times. You can't clear the jet by blowing or sucking. No pricker available. I use a wire from a miniature Rolson wire brush. For a long time this worked without enlarging the hole. Another cause is when your refill can is getting low. I believe most of the propane has gone. I always time how long to the safety lifting. Any longer than 8 minutes, clear the jet. I've never used hot water to fill the boiler. It's never empty. I've never had any soot either. What I've never found out is where the crud comes from in the first place. Have suspected forming lubricant inside copper pipework, or in the can but never found an answer.
Jerry.

flashtwo

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Re: Lack of ooomph
« Reply #4 on: November 06, 2014, 09:32:10 am »

Hi Greg,

Just been looking through my old post ( http://www.modelboatmayhem.co.uk/forum/index.php/topic,15817.225.html , 29 March) on the flash steam control system.

I was having similar problems and kept cleaning the gas jet, but eventually found that it was the gas control valve's soft lead seat that had distorted and closed up.

The other possibility is copper oxide inside the gas pipe (caused by soldering heat) dusting off and blocking the jet.

The colder weather could be causing the gas tank to reduce in pressure - is it very cold to touch? Hand warming the cylinder will increase the pressure for a while. The cold weather performance encouraged me to invert the gas cylinder and use the fuel in its liquid form, though this requires a fuel evaporator built around the burner. See my latest photos in the Edwardian Steam launch thread ( http://www.modelboatmayhem.co.uk/forum/index.php/topic,37563.25.html ) showing the burner with the evaporator coil.

Ian.
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SailorGreg

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Re: Lack of ooomph
« Reply #5 on: November 06, 2014, 05:47:50 pm »

Thanks one and all for the responses.  I have dismantled the burner and gas feed plumbing to check and as far as I can see I have a good gas flow to the jet and (visually at least) no jet blockage.  No obstruction in the chimney and can gas burning generate soot? Even if it can I don't think I've run the plant enough to make that the problem.  My last run was an experimental one in the garage with the boiler half full, and I got the same poor result.  It wasn't that cold and the gas tank is right next to the burner, so I don't think cold is the problem.  And Jerry, my filling can is still 2/3 full so I think that's OK.

Hmmmm.........

I think I will focus on the gas supply and re-check the whole run.  I will also blow the jet with compressed air and, if I can find a wire thin enough, give it a little poke.  If that doesn't do it I will splash out on a no 8 jet and see if that makes any difference.

And I will check my valve timing - it is a while since I looked at that and it could probably stand a good hard look - although I don't really understand how that might cause my pressure drop?

Anyway, thanks again and I'll let you know how I get on.

Happy sailing!

Greg

Jerry C

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Re: Lack of ooomph
« Reply #6 on: November 06, 2014, 05:56:58 pm »

Greg, your plant is virtually identical to mine. I use a no. 5 jet. This, when the jet is clean raises steam (60psi) from cold in 8 minutes.  Any longer and the jet needs clearing. The jet looks clear but pricking it resolves the problem. I've bought a no. 8 jet but not tried it yet as the hole looks huge compared to the no. 5. Let me know how you get on.
Jerry.

flashtwo

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Re: Lack of ooomph
« Reply #7 on: November 06, 2014, 06:06:09 pm »

Hi Greg,

For a thin wire you might try one of those needle threaders that has a loop of very fine wire which pokes through the eye of a needle (I don't dare suggest where you might obtain one from!).

Soot is the result of not enough combustion air to convert the carbon into CO2; my pilot light is from just a fine hole in a copper pipe and doesn't induce an air flow like the normal nozzle.

Regarding the slide valves - my D10 had very poor performance after not running for a long period. I found the steam oil had left quite a substantial deposit in the valve chest, which prevented the sliding valve from seating properly and letting the steam just sail through. I scraped the deposits off and gave the valve chest a good clean and the performance was good as new.

Ian
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steamboatmodel

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Re: Lack of ooomph
« Reply #8 on: November 06, 2014, 11:19:10 pm »

Greg,
What type of water are you useing in your boiler?
Gerald
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KBIO

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Re: Lack of ooomph
« Reply #9 on: November 07, 2014, 11:41:57 am »

Hello!
If i can help, and if the problem is coming from dirt inside the jets for un-plugging them , I use metal guitare string.
There is every size adapted for the the jets:
.008/.038 : .008/.011/.014/.022/.030/.038...Extra light
 .009/.042 : .009/.011/.016/.024/.032/.042...Light

 .009/.046 : .009/.011/.016/.026/.036/.046...Custom light
 .010/.046 : .010/.013/.017/.026/.036/.046...Regular
 .010/.052 : .010/.013/.017/.030/.042/.052...Heavy Bottom
 .011/.048 : .011/.014/.018/.028/.038/.048...Heavy
 .012/.054 : .012/.015/.026/.034/.044/.054...Jazz light
 .013/.056 : .013/.017/.026/.035/.045/.056...Jazz Medium

Also, remember that there is always debris inside the gas bottles. So to avoid these to get inside my gas tank, I use a fuel filter like thoses on the RC aeroplanes.I sometime add a small piece of coton to be safe.
Still I get the jets plugged from time to time. :embarrassed:
Regards.
 

Jerry C

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Re: Lack of ooomph
« Reply #10 on: November 07, 2014, 12:12:36 pm »

KBIO, brilliant! Thanks.
Jerry.

pettyofficernick

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Re: Lack of ooomph
« Reply #11 on: November 22, 2014, 07:32:29 pm »

I have noticed that it takes longer to raise steam when the ambient temperature is low. The quality of the flame at the burner seems to degrade the colder it gets, and if the gas tank and the refill cylinder are both cold, it is harder to fill the tank, the combined gas laws explain why. If there is a temperature difference between the tank and the refill, filling is easier, cold tank, warmer refil. In order to make lighting up easier, I stand the tank in a little warm water for a few minutes, this usually solves the problem. Jets are quite inexpensive, so I always carry a couple of spares, I have noticed the gas can be quite mucky, depending on manufacturer. Finally, I keep meaning to buy a cheap set of electronic kitchen scales so I can fill the tank by weight, in an effort to take the guess work out of filling up.....
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flashtwo

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Re: Lack of ooomph
« Reply #12 on: November 22, 2014, 07:44:22 pm »

Hi,

I use the gas cylinder inverted, draw off the liquid fuel and pass it through a coil around the burner. The pilot flames impinge on the coil and evaporate the liquid fuel, which then goes to the gas control valve and then back to the main burner. No evaporation occurs in the gas cylinder, preventing it from getting cold and the fuel pressure is maintained throughout the cold spell.

I have declared this method to the model boat insurance company and they didn't raise any objections.

I weigh the gas cylinders before and after a timed run to get some idea of fuel consumption.

If you look on the Edwardian Steam Launch thread, you can see that I recently had problems with the fuel evaporator caused by the pilot flames being undersize.

Ian.
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pettyofficernick

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Re: Lack of ooomph
« Reply #13 on: November 22, 2014, 07:51:37 pm »

Jerry, I have tried no 6 jet, gas consumption went through the roof and the roaring was quite alarming. Ian, I use a standard in flue ceramic burner, so no pilot light, I too have a near identical set up to Jerry and Greg....
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frog32

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Re: Lack of ooomph
« Reply #14 on: November 23, 2014, 02:29:46 pm »

Hi all. I thought I would add my 6d worth of experience to the current debate on oomph. 
I have an identical launch and running gear as Greg, in fact we both started building at the same time but Greg was the hare and I the tortoise!  My project was eventually completed in April this year so I have been happily sailing all summer and to date with no problems at all.  The following is my procedure which might help, or at least give Greg some ideas that may help solve his problem.
The only modification I have done is mount a small dial with a pointer on the Maccsteam gas tank outlet valve and also dropped a small O ring in the top of the Ronson filler connection, the reason for which I will explain later.
I fill the boiler to 5mm from the top of the sight tube. I purchased a small, pocket sized electronic scales off eBay for a fiver.  The empty gas tank weighs 400g.  I then open the gas valve very slightly to act as a bleed and then start filling the tank. Each minute puts 10grams of gas in the tank and I fill for 4minutes giving me 40gm of gas. The reason I fitted an O ring was that I got a lot of unessesary gas leakage around the gas filling nozzle but now if I put 40gms of gas in the tank my filling gas cartridge weighs 40gms less, so no wastage.

I then fit the gas tank, open the gas valve and light the burner which glows a nice blue colour and 8 mins later the pressure gauge is at 25psi and I have used 10gms of gas. I then turn the gas valve back to a third opening and the burner is a reddish yellow glow.
With this setting I get 1/2 hr of fast and slow sailing and in this time the pressure is never less than 15psi. I have found that the Graham engine runs happily at 10psi.
At the end of the run the gas tank may have a couple of grams of gas left and the boiler water level is about a couple of ml above the bottom of the sight tube.
For the second run the gas tank is now slightly warm because I have fitted the gas tank next to the condenser with a heat shunt mounted between them so I now need to warm the gas filling cartridge to allow the gas to flow into the gas tank. I have solved this by buying a couple of hand warmers from Lidl, the type that you click a little disc inside the bag of fluid and they start to heat up and will stay warm for a few hours and are reusable up to 1000 times. I put this in my pocket, slide in the gas cartridge for about a minute to warm up and then I have no problem refilling the tank. These packs are readily available on the internet.
The biggest complaint from the steamers at my club is trying to fill gas tanks especially in the winter so I am hoping that I may have solved it.


Greg, I really don't think you need to increase the jet size as from the above you can see that I have never had to use the full gas flow to maintain pressure and the Maccsteam boiler that you and I have produces more than enough steam for the Graham engine.


I use the Gosytem gas from B&Q and have never had to touch the burner or jet and I have run a lot of hours to date.


Apologies for the rambling but hope that Greg can find some direction for solving his problem.


Roger
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pettyofficernick

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Re: Lack of ooomph
« Reply #15 on: November 23, 2014, 04:05:32 pm »

Jerry, I have tried no 6 jet, gas consumption went through the roof and the roaring was quite alarming. Ian, I use a standard in flue ceramic burner, so no pilot light, I too have a near identical set up to Jerry and Greg....

For No6 jet read No 8 jet, slight senior moment with the keyboard occurred.....
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Jerry C

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Re: Lack of ooomph
« Reply #16 on: November 23, 2014, 04:15:31 pm »

Greg, agree with all Roger says, except my gas tank only takes (today) 45 seconds to fill. Today in 8°C ambient temp, 8secs to 60psi and a total run with gas valve full open of 30 minutes plus. Flame sluggish for first 10mins until gas tank warmed by boiler back when she really took off.
Jerry.

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Re: Lack of ooomph
« Reply #17 on: November 23, 2014, 04:35:43 pm »

A couple of variables between us. 1) My boiler horizontal.
2) I have a coil of 5 turns 5/32" tubing in the funnel, (economiser). No. 2 must make a difference to heat transfer inside the fire tube as coil is a restriction. The feedwater is at 100°C at clack valve. Funnel top is cool. I got very little condensate in de-oiler today. Suggest you disconnect feed water from de-oiler and put your coil in the funnel. If you do try this, keep us posted on results. FYI, if I run engine at full throttle I can't maintain more than 20psi. If I use 1/2 throttle pressure steady at 35psi. So everything on my rig seems pretty well sorted. Only problem I have now is that feed pump appears to have improved with use and now occasionally I have to crack open the bypass to maintain level.
Jerry.
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