DIY drybag valve?

Looks good.  Coroplast and bungee?  What’s it weigh?

Sea To Summit sells compression dry sacks w/ an eVent panel at the end in lieu of a mechanical valve.  They are well reviewed on rei.com.  eVent is avail by the yard @ $12.

If you’re interested in installing a mechanical valve in an existing bag, I’d suggest either installing a Presta valve from a bicycle tube, or the valve from a Ziploc Space Bag.  For the Presta, you want a threaded valve body, and if you go Ziploc, do some research on your materials to be sure you choose a suitable bonding agent to attach the valve.

eVent has advantages in weight and reliability.

I bonded a few layers of crazy carpet plastic with thin foam. Bungee. The weight is about 250g. Not bad. I’ll take a look at sea to summit dry bag. Thanks!

. THERMAREST sells replacement valves for their mattress

If you only ever want air to LEAVE* the dry bag (in burp mode) and you unroll the neck to get into it, there are tiny little check-valves in the aquarium aisle of Walmart, Petco and any pet store.  Whether you mount it directly into a corner of your dry bag or attach it to a length of vinyl tubing, if you point it to flow OUT, then every manipulation of the bag will make it smaller in volume.

*to reverse the function (fill the bag), you could simply give the check valve a yank to detach it from a length of vinyl tubing.  A puff of air by mouth would then quickly pressurize the bag.

A high-flow version is in some skin-diving snorkels and I look for them at Salvation Army.  It is also a low-pressure flapper check valve, but 3/4″ to 1″ in diameter so it allows a much higher flow through it.  When present, they are located at the low point of the snorkel so that one may more quickly clear the snorkel of sea water.  I doubt you need that for the size of dry bag you’re using, but if someone had a bigger set-up. .  .

I would use a repair valve for a kite. Cut a hole, spread adhesive and insert the valve from the inside. Has worked great on some MYOG air mats.

Ryan

Now that’s very interesting!!!  Thank you!