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Valerie E
(Wildtowner) - M

Locale: Grand Canyon State
A Question for You Science-Minded Folks... on 09/10/2013 16:53:21 MDT Print View

As you know, Exped sleeping mats/pillows have "one way" valves (a separate "inflation" and "deflation" valve). If one-way valves exist, why doesn't Thermarest make a self inflating mat with one standard (2-way) valve PLUS a one-way deflation valve? That way, when you're setting up camp, you close up the deflation valve and open the 2-way (closing when the mat's inflated to your liking). When breaking camp, you keep the 2-way valve closed, but open up the deflation valve (and bye-bye wrestling match when rolling up the mat).
Surely I can't be the first person to think of this -- is there a physics reason why this wouldn't work?

And E
(LunchANDYnner) - M

Locale: Pacific Northwest
cost and weight on 09/10/2013 17:22:20 MDT Print View

Cost and weight. That's pretty much it. Their pads are successful/popular and work and their neoair products are where they focus their efforts for advancements.

If it ain't broke, don't fix it.

Erik G
(fox212) - F

Locale: THE Bay Area :)
valves on 09/10/2013 17:26:57 MDT Print View

If you're going to keep the 2-way valve closed during deflation, why make it a 2-way valve? Maybe I'm missing something.

Overall, I think An-D nailed it in his response though. Their valves work fine as is. I honestly don't have noticeably more trouble deflating a Neoair vs an Exped mat (have owned both).

I DO wish they made a better inflation bag though; one that could actually be used as a stuff sack/pack liner (need something to seal the inflation hole). The schnozzle works great with Exped mats.

Edit: Just saw you're referring to self-inflating mats. They are kind of a pain to pack up. What I've had success with is: loosely/casually roll/fold up the self-inflating mat up to get most of the air out, then close the valve and unroll. Now roll it up nice and tight, then open the valve again once you get near the end of the mat. This keeps the mat from wanting to self-inflate while you're trying to get it to deflate. The 2-stage process made it a lot easier for me when I was using a self-inflating mat.

Edited by fox212 on 09/10/2013 17:37:53 MDT.

Valerie E
(Wildtowner) - M

Locale: Grand Canyon State
Re: cost and weight on 09/10/2013 17:28:19 MDT Print View

>> If it ain't broke, don't fix it

I guess -- to me, anyway -- it's broke! Although I still think self-inflating pads are more comfy (and now they've gotten the weight down to +/- 16 oz), I haven't used one in over 3 years because I DESPISE the packing-up process. With my breath-inflated mat, it's an easy fold & go; no imitations of WWE needed.

Could one after-market install a deflation valve on an existing self-inflating pad, and if so, how? I'd sacrifice the ounce or two for the extra valve!

Ken Thompson
(kthompson) - MLife

Locale: Behind the Redwood Curtain
Re: valves on 09/10/2013 18:58:57 MDT Print View

I open the valve, fold up the pad and squeeze the air out. Then I close the valve and refold and start rolling. Then I reopen the valve. No battle. Once done close valve.

Valerie E
(Wildtowner) - M

Locale: Grand Canyon State
Re: valves on 09/10/2013 19:06:36 MDT Print View

What can I say, I guess I'm alone in my dissatisfaction... (and wish for improvements to the whole sleeping pad genre). Still haven't found one I truly like, except my car camping pad, which is so heavy and huge, it's laughable.

M B
(livingontheroad) - M
pad on 09/10/2013 21:16:12 MDT Print View

Open the valve while you are still lying on the pad, before you first get up. Let it deflate with you on it. then fold and roll to force last bits out, then close valve and it stays tightly deflated.

Generally, my pack is packed before I come out of my tent. Only things left to put in are the tent, and foodbag if its hanging.

michael levi
(M.L) - F

Locale: W-Never Eat Soggy (W)affles
neo on 09/11/2013 00:37:28 MDT Print View

They're is a high resistance when blowing up a neoair which is annoying.

David Thomas
(DavidinKenai) - MLife

Locale: North Woods. Far North.
Re: A Question for You Science-Minded Folks... on 09/11/2013 00:38:50 MDT Print View

Valerie,

I like it. We all learn the 2, 3, or 4 step process of getting more and more air out of a Thermarest during deflations, but it is a little tedious. And we cycle the valve open and closed many more times than if a check valve allowed for a 1-step deflation.

No physical laws are broken if your innovation is implemented. What's inside those one-way valves is a flapper check valve - look at a fancier snorkel sometimes.

Another variation would be to slip a snug-fitting check valve on the two-way during deflation. But I like your idea of two valves better.

Aaron Oxenrider
(theox26) - M

Locale: South Central PA
Re: A Question for You Science-Minded Folks... on 09/11/2013 07:31:25 MDT Print View

I actually have experience with both the TAR self inflating and the exped mats. The method already mentioned using a two step roll is the best I've found to roll up the self inflating mats and I've never had an issue with it.

Really, I think you have the wrong idea on how the two valves work on an exped mat. The inflation valve is a one way that won't let air back out when blowing it up. The deflation valve is simply an open (2 way) valve that lets the air out quickly.

So for a self inflating, the deflation valve wouldn't help at all. Also, if you reverse the inflation valve then the flap used would most likely snag on things on the out side and not work nearly as well. Even on inflation it mainly works due to the back pressure of the air you've already put in to inflate the mat.

Valerie E
(Wildtowner) - M

Locale: Grand Canyon State
Re: A Question for You Science-Minded Folks... on 09/11/2013 10:00:32 MDT Print View

I guess it's just a personal "pet peeve"...I've been backpacking since the late 1980s; I've done the 2-step process many times with my old TAR mats, and always hated the back-and-forth fussing with the valve and pressing down with my arms and legs. (I like the idea of opening the valve while lying down, using body weight to partially collapse the pad, closing the valve, and re-rolling -- I've never tried that one!)

Clearly most people aren't annoyed by this in the way I am, (except David, to a lesser extent) -- so if there isn't a perceived problem, then no one would be interested in its solution, and even if it were invented, no one would buy it!

BTW, I get Aaron's point about the deflation valve on Exped (it's essentially just a "hole" that lets air out, and the air has no reason to try to get back in) -- but I'm still not clear on why some kind of deflation-only valve couldn't be fitted to a TAR-type mat... THIS is why I went to law school instead of Med/Engineering!!! Contracts, conveyancing, etc: easy; science: hard. ;~)

Richard Fischel
(RICKO) - F
kiss (keep it simple s....) on 09/11/2013 10:47:12 MDT Print View

an additional valve is just one more thing to fail.

Larry De La Briandais
(Hitech) - F

Locale: SF Bay Area
Non-self inflating mats on 09/11/2013 15:20:59 MDT Print View

"...loosely/casually roll/fold up the self-inflating mat up to get most of the air out, then close the valve and unroll. Now roll it up nice and tight, then open the valve again once you get near the end of the mat. This keeps the mat from wanting to self-inflate while you're trying to get it to deflate. The 2-stage process made it a lot easier for me when I was using a self-inflating mat."

That's how I always rolled up my therm-a-rest and I still sure that method to roll up non-self inflating mats also. It works well and doesn't take but a minute or two.

Jennifer Mitol
(Jenmitol) - M

Locale: In my dreams....
Re: Non-self inflating mats on 09/11/2013 15:54:40 MDT Print View

Actually Valerie, I was terribly annoyed by the roll up process...which is why I made the switch to the exped in the first place. Of course, I love the expeds now, so it's not an issue to me anymore. I just can't see going back to a self-inflating one at this point...

Any reason you don't like the exped and it's most amazing schnozzle bag?? Rather than trying to reinvent the proverbial wheel, of course...

David Thomas
(DavidinKenai) - MLife

Locale: North Woods. Far North.
Warning, thread drift. on 09/11/2013 16:02:26 MDT Print View

Despite spending most of my work days in 1983-1986 convincing people to buy Thermarests (I felt and feel that self-inflating pads were one of the huge advances that decade, together with "yoke" suspension systems for framed packs and dry-as-you-wear-it thermal underwear (i.e. polypro), now I'm of two minds:

1) when I'm going for comfort, willing to accept less reliability and more weight (albeit at half the weight of 30 years ago), then I carry a self-inflating pad.

2) when I'm going UL to SUL or going for long distances, then I use closed-cell foam because it multi-purposes as some of the structure in my UL pack, it is resistant to cinders and sharp rocks, and the weight is lower.

On the ever-present third hand, when I'm traveling at 35,000 feet, I bring my smallest self-inflater. I'm not worried about a leak, I just was some comfort while sleeping at gate C-7 from 12:45 am to 6:30 am in the minimum volume in my carry-on.

Larry De La Briandais
(Hitech) - F

Locale: SF Bay Area
Self-Inflating mats (TAR style) on 09/11/2013 16:03:33 MDT Print View

You can't simply open a valve and deflate a TAR type mat. It requires something to compress the foam inside. This can be partially done by laying on it, but the easiest way is to roll up the mat. If the valve is open the air can escape while the foam is being compressed. You could have another valve with a check valve (as suggested above), but it would only keep you from needing to close it when the mat is rolled up. You will still have to compress the foam, unless you have some sort of "pump" to force the air out of the mat.

Edited by Hitech on 09/11/2013 16:05:48 MDT.

Valerie E
(Wildtowner) - M

Locale: Grand Canyon State
Re: Non-self inflating mats on 09/11/2013 16:07:25 MDT Print View

I'm with you, Jennifer! (And thanks for understanding that I DO know HOW to roll them up - I just think it's unnecessarily uncomfortable and annoying)...I switched to Exped first, but their fabric is too noisy (seriously, my husband went across the creek to sleep because of the noise). Now I have a Klymit, which is less noisy, but maybe a hair less comfy than the Exped...If you don't toss and turn, Expeds are fine.

But I still fondly remember the extra cushiness added by that open cell foam in self-inflating mats, and I wondered (in my let's-reinvent-the-wheel way) if I could have the "best of both worlds"...

LOL, David -- re: airport camping!
I am torn, for next year's planned JMT thru-hike, between my Klymit and a Z-lite (I must say, the bomb-proofness of the latter is attractive; just not sure I want to sign up for +/- 20 nights of relative discomfort).

And Larry...a pump, hmmmmmmmm... maybe a "reverse" version of an Exped snozzle-type thing...

Edited by Wildtowner on 09/11/2013 16:12:58 MDT.

Stephen M
(stephenm) - MLife

Locale: The Great Lakes Bay Region
Exped Noise on 09/11/2013 17:07:06 MDT Print View

I had to laugh at that as my wife and I got accosted by a tent neighbour while car camping in the Belgium Ardennes saying our pads kept them awake, I founds dabbing some some seam sealer on the bottom pads stopped them moving.

Jennifer Mitol
(Jenmitol) - M

Locale: In my dreams....
Re: Exped Noise on 09/11/2013 17:16:56 MDT Print View

Hmmm...noise from the exped? I've had a few now and have never had a noise issue. And I'm super sensitive to that sort of thing....

My current favorite is the downmat UL 7 short. Slept like a rock on the JMT......

Stephen Barber
(grampa) - MLife

Locale: SoCal
re: Re: Exped Noise on 09/11/2013 19:10:46 MDT Print View

I'm with Jennifer here!

When I had a brief flirtation with the Thermarest XLite, it kept both me and my wife awake with its loud crinkling. But my Exped UL Synmat is as quiet as the grave. Only my snores awake the sleeping!