The MSR MicroRocket — Review Complete

A few years ago, the night before meeting some fellow Californians for a Lost Coast trip, I noticed my PR was getting slower and slower, it was only 4-5 years old then and not used that much. I swapped canisters and it did better. A few other times too, same results after I removed the stove and reattached it. Since then, I tighten it pretty good now and no issues, the flat washer in there may be getting harder, shrunk up or the pointy part that allows fuel to flow is worn ever so slightly. Not sure, as I take care of key gear.
Duane

Roger’s suggestion of silicon grease seems like it might be the way to go, the idea being to decrease wear. I look at something like Loctite as more to prevent leaks. Loctite might make sense if your threads are worn (but I think it’s better to replace the stove!), but silicon grease makes more sense if one is trying to prevent wear.

HJ
Adventures In Stoving

>"Loctite might make sense if your threads are worn"

I don't have as much experience as some of you with stoves – only a couple of dozen stoves over the last 35 years and 2 years in the early 80's servicing stoves professionally.

But I know pipe threads, union threads, and hose threads.

Pipe threads (as in threaded galvanized pipe, brass pipe, threaded copper adapters, and threaded PVC pipe are tapered. They are designed to wedge together tightly such the metal deforms and mostly seals the gaps between the male and female threads. It is to these threads that one might add teflon tape or pipe dope, my favorite being Rector Seal #5 because it handles just about anything to just about any pressure. Really. Read the label.

Hose threads and the threads on a union are NOT designed to be water-tight or gas-tight. Their purpose is to align and seal a gasket (for hose threads and dielectric unions and tiolet/sink connections) or a machined brass-steel junction (in the case of unions). You DON'T add telfon tape or pipe dope to these threads as they will ALWAYS leak, with or without dope if the gasket leaks.

So if a canister adapter is leaking: don't think about the threads LEAKING. Consider if the threads are able to align and compress the gasket adequately. Remember that rubber and similar polymers get stiffer in cold weather and unlike almost everything else, gets larger, not smaller, in cold temperatures. Also consider that such gaskets do age. I just accept that the multitude of propane devices around the house will need replacement gaskets every 4-8 years and keep a few extra around (but not many, because they age in storage, too).

If you're getting leaks at the top of canister, I'd start by replacing that gasket. Rather than trek off to REI or some such place, I can almost always find a fit at an auto-parts store and occasionally at Home Depot.

Hi Travis

> Is it necessary to tighten the canister a bit more to ensure a good seal with the hard gasket?
Not if they are good Viton O-rings. Tightening hard wears the thread out FAST.

> MSR Windpro, and from memory, I think that has a large, flat gasket instead of an O-ring type seal.
To the best of my memory, it has the conventional O-ring SEAL, plus a rubber washer which does little or nothing.

Cheers

Hi Jim

> the PocketRocket's threads are aluminum and the GS-100's are brass.
I haven't got a new PR, but it is possible that the aluminium body has been hard anodised. This will certainly prolong the life of the thread if ALWAYS treated gently.
But I have to say, 'cheap, cheap, Chinese'.

Cheers

Hi David

See http://www.bushwalking.org.au/FAQ/FAQ_GasStoves.htm#Oring

I quote (myself):
"For most stoves the O-ring is a BS011, and if you buy some you should buy them in Viton rubber, not a cheaper version. However, some of the Primus stoves use a BS108 O-ring instead. This is a bit fatter than the BS011, which is not a bad idea. I suspect you could use a BS108 O-ring in place of a BS011 if desperate, but you might need to screw the stove down much harder to get gas flow. This would make the brass thread on the stove wear out quickly. You should be able to buy these O-rings at good hardware, engineering or auto parts shops. If in doubt about the size, take the stove with you."

Yes, I always carry spares with me!

Cheers

The MSR PR has a large flat rubber gasket at the base of the stove. This gasket is NOT responsible for providing a gas tight seal. There is a small o-ring inside the threaded base of the stove and this provides the gas seal. So what is the large flat gasket for? It enables the weight of the stove + pot to be supported by the rim around the valve at the top of the canister. But, there is no specification for canisters that specifies what the height of this rim is relative to the height of the Lindal valve. The large rubber gasket allows for small variations in this tolerance and therein lies the problem. I well remember a time when my PR failed to work in winter with a full canister: with the large gasket being hard due to the cold, I had to really crank the stove onto the canister and even then I could only get a tiny flame. The pin in the base of the stove was just not opening the Lindal valve in the canister. Now take a close look at the threads on the canister valve. Use a magnifying glass, or take a close-up photo. The threads are not well formed: they are _really_ shallow. Because of that they only contact the very tip of the thread on the stove. So, if you need to crank the stove on hard, you risk stripping the thread on the stove. Teflon tape will make no difference. If the thread is aluminium, that risk is magnified.

So, it really comes down to the canisters – poorly formed threads and unspecified tolerances, plus aluminium being a poor choice for the stove thread. There will be variations between brands too (perhaps "Billy Goat" sticks to one particular brand?). The Campingaz Easy-Click system is far superior in this respect.

David Thomas wrote: > So if a canister adapter is leaking: don’t think about the threads LEAKING. Consider if the threads are able to align and compress the gasket adequately. Remember that rubber and similar polymers get stiffer in cold weather and unlike almost everything else, gets larger, not smaller, in cold temperatures. Also consider that such gaskets do age. I just accept that the multitude of propane devices around the house will need replacement gaskets every 4-8 years and keep a few extra around (but not many, because they age in storage, too).

Ah, good point. The threads in this case hold everything in place, pressed up against the gasket. If the threads are so worn that they won’t hold things against the gasket, Loctite isn’t going to help much.

Thank you, David.

HJ
Adventures In Stoving

Stuart Robb wrote: > take a close look at the threads on the canister valve. Use a magnifying glass, or take a close-up photo. The threads are not well formed: they are _really_ shallow. Because of that they only contact the very tip of the thread on the stove. So, if you need to crank the stove on hard, you risk stripping the thread on the stove. Teflon tape will make no difference. If the thread is aluminium, that risk is magnified.

One hardly needs a magnifying glass. The shallowness of the thread is apparent even to my unaided eye.

Stuart Robb wrote: > The Campingaz Easy-Click system is far superior in this respect.

Or the SuperFly’s “collar clamp” type connector. Were I to do a long trail, I might seriously consider the SuperFly or the semi-MYOG SuperGnat

HJ
Adventures In Stoving