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Stove gurus: Did I melt the Lindal valve on my stove canister?
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David Drake
(DavidDrake) - F - M

Locale: North Idaho
Stove gurus: Did I melt the Lindal valve on my stove canister? on 06/15/2012 17:50:31 MDT Print View

Had my Snow Peak GS-100 fail a couple days ago--actually it appears to be a canister failure, not the stove itself.

Using a windscreen and boiling water, the stove suddenly quit. Temps were 70s (F), 10-15 mph winds, was checking the canister and although it got warm, was never too hot to touch. When the stove cooled I pulled off the canister, which still had fuel. The Lindal valve looked damaged, and the stove body was unable to release gas from the canister.

I was just using the stove to make coffee on a road trip, so only an inconvenience. Obviously, this would have been a bigger deal on an actual hike.

Bought a new canister today and looked at both valves with a loupe. The failed canister *appears* to have a melted valve, as if the brass pin on the inside of stove body got hot enough to melt into the plastic pin on the canister.

Anyone else ever experience this? Is my windscreen at fault? Could it have been a defective valve?

Pics of "melted" and normal valves below, as well as my MYOG windscreen setup.

Bad valve:
bad valve

Good valve:
good valve

Windscreen:
windscreen1
windscreen2

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
Re: Stove gurus: Did I melt the Lindal valve on my stove canister? on 06/15/2012 18:11:59 MDT Print View

I had a canister that leaked when I unscrewed the stove, so I just screwed the stove back on until I emptied that canister

Nick Gatel
(ngatel) - MLife

Locale: Southern California
Re: Stove gurus: Did I melt the Lindal valve on my stove canister? on 06/15/2012 18:41:58 MDT Print View

I think you were lucky it didn't explode. The bottom half of your screen might be okay, it is similar to the one Snow Peak sells. The the upper portion is probably a problem.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Stove gurus: Did I melt the Lindal valve on my stove canister? on 06/15/2012 19:34:29 MDT Print View

Hi David

Well, assiming the two canisters are the same brand, then it does look as though you partially melted the valve. VERY VERY BAD. Be grateful nothing worse happened.

It is worth noting that the failure mode for the Lindal valve under these conditions is to shut off. Yes, a fail-safe mechanism, very commendable. But never rely on it!

Why did it happen? Your windshield/baffle combination looks VERY DANGEROUS to me. I think it trapped a huge amount of 1000 C exhaust air and caused the Snow Peak stove to get extremely hot - probably well over 100 C, maybe over 150 C. Could it have reached 200 C? Dunno, maybe. This is so far outside safe use conditions that you are lucky the valve melted and the stove shut down the way it did. You could have had a fireball.

Yes, I know some people love to ginger up their stove systems like this, but the stove is NOT designed to handle the huge increase in temperature it creates. No use sueing the vendor: YOU violated all the safety rules. Just don't do it.

For the record: I do use a windshield around my stove, but the windshield sits on the ground and comes about 1/2 way up the pot wall. It has an opening maybe 3 cm wide or more at the valve side for air inlet, and it leaves a 2 cm gap between the pot and the shield for exhaust. AND I monitor the temperature of the canister and the behaviour of the stove all the time.

By the way: since the stove has experienced such a high temperature, you should probably replace the O-ring on the needle valve and the O-ring in the screw thread. I recommend Viton replacements.

Cheers

Ken Thompson
(kthompson) - MLife

Locale: Behind the Redwood Curtain
Re: Stove gurus: Bad windscreen design on 06/15/2012 20:00:25 MDT Print View

Looks a lot like this one.

http://www.backpackinglight.com/cgi-bin/backpackinglight/00041


This article probably should be removed

Edited by kthompson on 06/15/2012 20:01:15 MDT.

David Drake
(DavidDrake) - F - M

Locale: North Idaho
Re: Re: Stove gurus: Did I melt the Lindal valve on my stove canister? on 06/15/2012 21:46:55 MDT Print View

Thanks everyone. I take the cautions to heart, esp. Roger's as I've followed all his stove articles on BPL with interest. Rest assured, I don't intend to use this windscreen again, although I have used it before without issue. And of course, I take full responsibility for anything that happens when I use a stove.

However, it's worth pointing out what I used appears to be very similar to a windscreen design published on BPL by Ryan Jordan:

http://www.backpackinglight.com/cgi-bin/backpackinglight/00041

I thought I followed that article pretty closely in making my own. Looking at the article more closely now, it appears RJ used a larger pot and canister, perhaps creating more air space around the stove burner. Both of us have about a 1/2" gap between pot and screen, about half the space Roger recommends. It may be unclear from my photos, but my windscreen only extends halfway up the side of the pot, and the valve body of the stove is entirely outside the enclosed space, and a good 3/4" (2 cm) from the bottom of the reflector.

So I don't know. As I said in the original post, I monitored the canister closely throughout, as I do any time I use a windscreen. Flame level was moderate, for good fuel efficiency. In fact, my hand was touching the top of the canister and the valve body of the stove when the valve failed. The canister and valve body were warm to the touch--warmer than usual, but I had no problem keeping my hand in place. If the valve did melt, obviously something at some point was "well over 100C" but nothing I could get my fingers on. There's no evidence of any heat damage to the thread o-ring or stove base washer. The valve still works smoothly. No evidence of heat oxidation on any of the brass parts. Obviously there could be damage I can't see, but the stove seems to work fine on a new canister--much better in fact than I remember the canister that failed working (most of that canister was used in a [well-ventilated] cabin, without windscreen). However, when screwed and unscrewed from the new canister there seems to be a point where the Lindal valve is depressed before the thread connection is fully sealed, and a bit of gas is vented. O-ring replacement seems prudent. Roger, do you happen to know the size off-hand?

Is it possible for the flame to have burned back into the stove valve body and melted the Lindal valve (if it indeed melted) without raising the temperature of the canister and stove beyond "touch" levels? Due perhaps to a too-tight windscreen, low flame, and I-don't-know?

Edit: Was still writing this as you posted, Ken. As noted, that article was my reference and inspiration. Be interesting to see if RJ still uses that style windscreen. But again, I take full responsibility for the risk with anything I make, regardless of the source.

Edit 2: Will Reitveld, in another BPL article

http://www.backpackinglight.com/cgi-bin/backpackinglight/wind_dynamics_and_windscreen_design_part_2.html

has a photo of a windscreen he made for the Coleman Exponent F1 also very similar in appearance to mine. He also references the Jordan article--in fact, I believe that's the link I originally followed. Again, pot size may make a significant difference in the actual air space around the stove (hard to tell from Will's photo what size pot/canister he's using. And it's ultimately my risk and responsibility. But I don't think I was building anything *apparently* beyond the scope of what's been presented in past BPL articles.

Edited by DavidDrake on 06/15/2012 22:09:24 MDT.

Stuart R
(Scunnered) - F

Locale: Scotland
Re: Stove gurus: Did I melt the Lindal valve on my stove canister? on 06/16/2012 05:05:09 MDT Print View

The failed canister *appears* to have a melted valve, as if the brass pin on the inside of stove body got hot enough to melt into the plastic pin on the canister.

I would agree with that. It looks to me that the enclosed nature of your windshield has caused the burner to get hotter than normal and that heat has been conducted down the mixer tube so the base of the stove, including the pin that depresses the valve, has gotten hot and melted the plastic. The ability of the mixer tube to conduct heat varies with stove design, some tubes conduct heat better than others. Factor are tube material (aluminium, stainless, titanium), cross-sectional area and size of air holes. So a different stove may or may not be susceptible to this. In any case, you need more air flow around the burner so that it does not get so hot.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: Re: Stove gurus: Did I melt the Lindal valve on my stove canister? on 06/16/2012 05:41:25 MDT Print View

Hi David

Yes, others have made somewhat similar enclosures, but usually with a LOT more exhaust room around the pot. Your pot had a very small diameter. You need to let the hot air out.

> O-ring replacement seems prudent. Roger, do you happen to know the size off-hand?
Under the stove: BS011. Should be readily available in the USA.
The needle valve uses (I think) a small metric O-ring.

> However, when screwed and unscrewed from the new canister there seems to be a point
> where the Lindal valve is depressed before the thread connection is fully sealed,
> and a bit of gas is vented.
Yes, this happens with some stove/canister combinations. There's a sad lack of any real dimensional standard. If/when it happens, just keep screwing or unscrewing fast.

For yet more info, see the FAQ pages:
file:///C:/FAQ/FAQ_GasStoves.htm

And for a more safe design of what you want, see the picture at:
file:///C:/FAQ/FAQ_StovesTech.htm#Wind

Cheers

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
Re: Stove gurus: Did I melt the Lindal valve on my stove canister? on 06/16/2012 08:59:22 MDT Print View

So, what is it that makes the windscreen unsafe?

Is it the horizontal circle heat refelector piece?

More specifically, is it that the burner head to canister connection (including the needle valve and Lindal valve) is above the circle reflector piece so it gets too hot?

The needle valve/Lindal valve could get quite hot, but the much larger mass of canister and fuel would only get a little hot so if you touched that with your hand you could be fooled into thinking everything's okay.

I agree those two articles look dangerous and should be deleted.

Also look at other articles such as http://www.backpackinglight.com/cgi-bin/backpackinglight/myog_group_pot_stand_and_windscreen.html and mine http://www.backpackinglight.com/cgi-bin/backpackinglight/myog_aluminum_windscreen.html?forum_thread_id=31119&startat=20 but I think both of those are okay because there's no circular reflector between canister and burner.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: Stove gurus: Did I melt the Lindal valve on my stove canister? on 06/16/2012 15:39:35 MDT Print View

> So, what is it that makes the windscreen unsafe?
Very simple. These stoves are designed to be operated in open air. If the hot air from the flames can't escape fast enough such that either the stove or the canister start to get hot, it's unsafe. No magic, no secrets, just keep both from overheating.

Canister: should always be cool enough that you can touch it without an 'ouch' reaction. That means below 40 C. (The pain receptors in your skin are triggered at about 43 C.) And 40 C is below the DOT requirement of being safe at 50 C.

Stove: yes, this will get hotter, especially at the burner head. But the valve section at the bottom should not get too much above 40 C either.

Windshield: fine if used as a wind shield, with plenty of room for hot gases to escape at the top and fresh air to come in at the bottom (to keep the CO levels down). Not good if used as an oven.

Heat reflector: generally not a good idea imho, as there is potential for overheating. Not needed either imho.

Cheers

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
Re: Stove gurus: Did I melt the Lindal valve on my stove canister? on 06/16/2012 15:50:02 MDT Print View

Should Will and Ryan's articles mentioned above be deleted?

It seems prudent based on what you and other's have said

Ken Thompson
(kthompson) - MLife

Locale: Behind the Redwood Curtain
Re: Re: Stove gurus: Did I melt the Lindal valve on my stove canister? on 06/16/2012 18:50:40 MDT Print View

Should Will and Ryan's articles mentioned above be deleted?

It seems prudent based on what you and other's have said

+1 But you know that already.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: Stove gurus: Did I melt the Lindal valve on my stove canister? on 06/16/2012 21:06:07 MDT Print View

> Should Will and Ryan's articles mentioned above be deleted?

Well, Will's articles do not present a significant danger imho. You will note that the first photo in part 2 shows a safe configuration: there is plenty of room for the hot gases to escape, and the bottom radiation shield is well below the top of the canister. It really is shielding the canister - although it is probably doing very little over all.

Will's second photo in part 2 shows a partially melted stove, and he mentions damaging three stoves from overheating. Seems fairly explicit to me.

Ryan's article ... well, let's just say I would not do that. But note the date of the article: 2001, when we knew a bit less about these stoves, and the clear disclaimer at the bottom:
'The information contained in this article is provided for informative purposes only and describes aftermarket modifications to canister stove systems that are not endorsed by any manufacturer. This information should be used at your own risk, realizing that there exists the possibility of canister overheating or permanent stove damage that could result in property loss, injury or death.'
(My bolding)

Cheers

Alan Bradley
(ahbradley)
RE: melted valve: windscreen deceptive looks? on 06/17/2012 05:10:08 MDT Print View

The original poster's windscreen looks deceptively safe to someone worried about canister temperature as the canister is not enclosed.

If the gas and canister material aren't conductive enough to mean that when the can side is at less than 43C that this also implies that the lindal valve section is at a reasonable temperature, then (as mentioned above) perhaps the stove valve section also needs monitored(this would presume it can never be at a lower temperature than the lindal pin). This seems a bit of non-relaxing way of making coffee/tea.

Now I wonder if that is the reason the instructions for the Primus windscreen (http://www.primus.eu/templates/pages/product.aspx?ItemId=87476) were changed to limit the list of suitable stoves and usage (I had thought it was because of heat transfer through the windshield attachment to the canister collar).
(some places show it used wrongly I think:
http://www.amazon.co.uk/dp/B001IOH4T2/ref=asc_df_B001IOH4T28361071?smid=A2J452NAFDME2B&tag=hydra0b-21&linkCode=asn&creative=22218&creativeASIN=B001IOH4T2&hvpos=1o1&hvexid=&hvnetw=g&hvrand=1556970563829084957&hvpone=&hvptwo=&hvqmt=)

It seems quite limited: I wonder why they don't make a commercial "kitescreen" style windshield instead. A rigid sectioned kitescreen (self-supporting on rocky ground) might be more convenient.


In the above posts, is the foil disc viewed as a heat deflector if below the valve but a reflector(as well) if above?

"he bottom radiation shield is well below the top of the canister"--
Should this be "below the top of the __something_else__"?, the .au FAQ just mentions a plain disc level with canister collar as OK.

Edited by ahbradley on 06/17/2012 05:12:03 MDT.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: RE: melted valve: windscreen deceptive looks? on 06/17/2012 05:28:28 MDT Print View

> is the foil disc viewed as a heat deflector if below the valve but a reflector if above?
Deflector, reflector, what's the difference? You don't need either, and are safer without them.

> well below the top of the canister
Yes, what I wrote was how I meant it.

With respect, all this may be missing the point I am trying to make:
If you bottle up the flame and exhaust too much, you can heat the stove up to a dangerous level.
It's as simple as that.

Skip all the fancy contraptions. Have a simple windshield around the stove by all means to block the wind (I do), but leave plenty of room for the hot air to escape!

Cheers

Alan Bradley
(ahbradley)
Re Re: RE: melted valve: windscreen on 06/17/2012 06:53:14 MDT Print View

Sorry, I didn't mean to obscure the point that "If you bottle up the flame and exhaust too much, you can heat the stove up to a dangerous level."

"> well below the top of the canister
Yes, what I wrote was how I meant it."
I am afraid I appear to be suffering an intelligence shortfall, as after re-reading the articles and post, I am not sure what that means:

does it mean that any such radiation shield should be below the collar of the canister, leaving the collar visible above the shield(like in Will-Rietveld's 1st photo at http://www.backpackinglight.com/cgi-bin/backpackinglight/wind_dynamics_and_windscreen_design_part_2.html)
I can't see how it could go any lower whilst shielding the canister top (but not touching it).

Edited by ahbradley on 06/17/2012 09:52:48 MDT.

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
RE: melted valve: windscreen deceptive looks? on 06/17/2012 07:44:00 MDT Print View

Sorry to keep "beating this dead horse"

But "not bottling up the flame and exhaust too much" isn't very clear

Not having a reflector (or deflector : ) is clear

If someone read either article, made a stove with a reflector, and then blew their stove up and possibly themselves, it would be too bad. Especially if they then went back and saw threads about this and nobody fixed the articles.

It seems like the only prudent action is to go back to those articles and recommend not having a reflector.

I remember you have said that (not having reflector) a number of times in the past, so really this is a question to Ryan, so I don't know why I'm saying this to you : )

What you've said about canisters overheating is good - if it's hot to touch you're in danger. But the valve/Lindal valve overheating is more difficult - no easy way to determine if it's getting too hot.

David Drake
(DavidDrake) - F - M

Locale: North Idaho
Lesson learned on 06/17/2012 10:10:49 MDT Print View

Thanks again for all the comments. Needless to say, I'll be using a windscreen along the lines of Roger's recommendations in the future. I feel fortunate this insight came without injury or significant damage to my stove.

@ Jerry: Just to clarify (as I mentioned above) the reflector on my rig was well *above* the valve body of the stove. As in Ryan's design, the reflector rests just above the hinge-points of the pot supports. I was touching the canister, the stove to canister connection, and part of the valve body of the stove when the canister valve failed--nothing felt *dangerously* hot. If the Lindal valve did melt (as seems likely) I'd say your observation is correct--there may be no easy way to tell it's happening.

Re: deleting the articles by Ryan and Will. Deleting anything from the internet that isn't outright libelous makes me nervous. I read Ryan's warning at the bottom of the article as being standard boilerplate. I read Will's caution about the windscreen/reflector he made for the Coleman F1 as being a problem with tipping, caused by the design of the F1's pot supports. I interpreted his hot link to Ryan's article and his mention that the Giga had a design more suitable for a Jordan-style windscreen as approval. This may not have been the intention of either article, but I don't think my readings were unreasonable, either. Certainly, I don't think I would have come up with this design on my own. And I did use this reflector/windscreen combination several times without incident (both testing and in the field) before this failure.

In my view, design parameters for this type of reflector/windscreen are a lot more sensitive than either article indicates--perhaps the articles could be edited to reflect that. For example, Ryan built his windscreen with foil, but suggested flashing would be a more durable option. I used flashing--perhaps the thicker aluminum trapped more heat in the enclosure. And as I've said, I think the small pot I was using (and correspondingly smaller enclosed volume) played a big role.

Finally, my experience is at best just one data point. I don't know definitively that the Lindal valve melted--the damage actually looks more ambiguous than it appears in the photos. What I take from Roger's comments is that a Jordan-style reflector/windscreen is unnecessary for good performance and has tremendous potential for disaster. I actually think of myself as pretty cautious about these things, and won't be using such a reflector/windscreen combo in the future.

Again, thanks to all for the comments and discussion. Thoughtful community response like this is what keeps me coming back to BPL.

Edit: strengthened a couple adjectives.

Edited by DavidDrake on 06/17/2012 10:30:21 MDT.

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
Re: Lesson learned on 06/17/2012 10:18:28 MDT Print View

I agree, I hate deleting stuff

Maybe just add something to say that upon further experience, reflector can be dangerous so best not to have it

Alan Bradley
(ahbradley)
Re: Re: Lesson learned on 06/17/2012 12:16:52 MDT Print View

I think, perhaps, what is meant is that,

1) a radiation shield below the stove itself? even below the canister collar? is OK but may be unnecessary for short burns (canister side temperature checks done as required)

BUT

2) any heat reflector disc above that canister height (i.e. attached to the stove itself) is bad, as this may allow the stove body become too hot due to trapped gases etc.

Hopefully this simple rule will be confirmed as correct .