Accucraft NG/G16 safety valves......

tac foley

tac foley

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Been running my WHR Garratt this afternoon, and finding that both safety valves start 'feathering' at around 40psi and then blowing at 50. It USED to be 50 and 60...

Now that Mr Saunders [WeeBee] over in the USA has stopped working, I'm a mite stuck as to figure our where to go to get a couple of replacement safeties.

Anybody here had this problem?

tac
 
Sure its not the gauge that's changed?
 
Gauge USED to read 60 + a smidgin and then blew off most effectively, that's why I painted the red line at that pressure for recording purposes. Now it feathers at forty-ish and has opened up fully at 50. The loco won't pull the skin off the proverbial at 40-50 psi, although it DOES move, sluggishly.

tac
 
Thanks for that - I'll get them out and send them off to him, unless, o'course, he's at the show.

tac
 
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Tony is probably right, get it to Mike.

Just because you've marked the gauge doesn't mean it's still correct. If it has been dropped, frozen or over-pressured it can be reading low. Even if you can discount all those, it still doesn't hurt to check it against another 'known' gauge.

You say it wont open a rice pudding, which is certainly more indicative of a lower pressure than required, but 10 psi under isn't all that much in the normal scheme of things, and likely still well within a normal running range.

I sense a full check up coming on.
 
Check a bolt hasn't dropped out of a reverser on one of the motions and make sure both burners are running right. One can get a blowback on a burner if the water in tender around the gas tank is too warm. Both may manifest as diminished rice pudding pulling power. Otherwise the good Mr Darby, he has ministered to mine. Max
 
'Dropping' or 'freezing' is not something I normally associate with a thirty-pound £4000 live-steamer, and over-pressure? How does that work? The valves used to blow at a minute tad over 60psi.

I agree that getting both burners alight can be a pain - that's why I stand on the right of the loco, which stands on a left-hand curve to expose as much of the smokebox opening as possible to allow the little mirror on a stick device to let me see both burners burning.

Here in temperate UK I tend not to use the water bath feature unless the outside temperature drops below 45F - after almost ten years of ownership, is this incorrect practice?

Lemme try it with some warm water in. I'll let you know what happens.

tac
 
I have a couple of locos with Matt's replacement burners fitted - might be time to get the BG done. Last time we spoke he didn't mention that he'd done a Garratt....

Do you have any video of the loco running with new burners?

tac
 
Matt made the burners specially for me last winter to match the existing ones. They are fatter and longer than his standard product. Getting the existing burners out is, however, a challenge!

Sorry, no video of it running but with all the mods I've made (removing exhaust back-pressure, improved lubrication, etc.) it'll pull a house down now.
 
tac foley said:
'Dropping' or 'freezing' is not something I normally associate with a thirty-pound £4000 live-steamer, and over-pressure? How does that work? The valves used to blow at a minute tad over 60psi.

tac
Click to expand...

I did not suggest that these adverse conditions would necessarily be met while the gauge was still attached to the loco, though that is possible. I spent some years occasionally recalibrating pressure gauges for a section of the 'Big Telephone Company'. Dropping a gauge on one side can strain the bourden tube inside and 're-adjust' the settings, likewise freezing, if water has got into the bourden tube (condensed steam), and likewise the strain of a gauge being subjected to excessive pressure (stuck safety valves?). We were cautioned to never fit even a new gauge without first calibrating it, for just these reasons.
 
None of the conditions that you noted have ever been encountered here in UK by my loco - needless to say, it gets coddled somewhat with a price-tag like that. Nor has the pressure gauge ever been removed for any reason.

And for Mr Willmore - perhaps I might persuade Matt to make me a set, too, by forcing money into his hands... ;)

I'll give him a call, after all, he already has one of my locos to fix up - one more can't hurt.

tac
 
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tac foley said:
Here in temperate UK I tend not to use the water bath feature unless the outside temperature drops below 45F - after almost ten years of ownership, is this incorrect practice?tac
Click to expand...

I always thought is was standard practice to fill the "bath" with warm water, at least after a few minutes running time. You will hear the burner start to "roar" as you fill up with warm, not hot, water (see another thread re' a melted slo-mo). It increases the gas's pressure and mitigates against its tendency to stay liquid as the tank is remote from the boiler area and not benefiting from the heat radiating from there. You will note the increased rice pudding skin pulling power as a result.

The good Mr Darby even made a mod to my NGG16 to assist - he fitted a valve to the back of the boiler, and a pipe to the gas tank area of the tender, that would allow steam to bled off to keep the water "bath" at a constant temperature for the duration of a run. It was done at his suggestion. The good Mr Darby has some experience of these engines as a longstanding Accucraft service agent (other Accucraft service agents are available) ;). Max
 
maxi-model said:
The good Mr Darby even made a mod to my NGG16 to assist - he fitted a valve to the back of the boiler, and a pipe to the gas tank area of the tender, that would allow steam to bled off to keep the water "bath" at a constant temperature for the duration of a run. It was done at his suggestion. The good Mr Darby has some experience of these engines as a longstanding Accucraft service agent (other Accucraft service agents are available) ;). Max
Click to expand...

That is the same principal as a Windermere Kettle, just to a lesser extent. In a W.K., most often fitted in steam boats, steam is run through a coil in the bottom of the container and brings water to the boil very quickly; obviously for the purposes of brewing up! :):)
 
Thanks, guys. TBH, I've been running it very successfully for the last nine years without using the tank facility unless it was what you would call cold. My many movies in Youtube testify to that, I think, including one run with 56 wagons in early February over at main131's track.

Thanks, Mr Dodger - I know Jason from the odd deal [great company to deal with, BTW] and I might ask him for a couple of SFs if the thing doesn't pan out after all.

@MM - that sounds a good idea using any spare steam like that. It is, of course, used all over the place in full-size practice where oil-fired steam locos that use bunker-type fuel need to keep it moving.

No doubt I'll be having a chat with Mr Darby at the show - I won't be able to take the loco over there as my weekend car doesn't have the trunk capacity...
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tac
OVGRS.org
 
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