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Steve Lindblom wrote: > >By using the partial mask , which has one of the one way valves removed, if > >the oxygen supply becomes depleted the patient will still be able to breathe > >through the open port > > I think you've got the partial rebreather confused with the modified non- > rebreathers that seem to be all you can buy these days. The difference > between a non-rebreather and a partial rebreather is that the non- has a > one way valve between the reservoir and the mask, so none of the exhalation > goes back into the reservoir. A partial rebreather doesn't and can't > provide more than 60% no matter what the flow. > > Unfortunately, for the reasons you mention, the non-rebreather masks > available have been modified by putting the air vent in place of one of the > two exhalation valves they used to have > > This is probably a good idea in general, but not for dive/DCS treatment, > where achieving a high PO2 is more important than it is in most other > emergency situations. > > The other problem with the vent is that, along with making it impossible to > obtain FO2's over 90% or so, it requires really cranking up the flow to get > even that. Once again, not a problem for med/EMT types, who have unlimted > O2 on hand, but a drag with a single D tank and an hour from shore. > > The OXY HACKER suggests pirating a valve from another mask and fitting it > to the non-rebreather mask in your dive O2 kit, taping over the air hole, > or covering it with a finger in order to get the highest possible FO2. > > If anyone knows of a source of the old style masks without the hole, let > us know - I'd really like to get some. It's too bad DAN won't address this, > considering how they are always going on about how critical that last 5-10% > of O2 is. > > -- The mask we are using in Canada is what i believe you are calling a modified non rebreather. there is a oneway valve between the reservoir bag and the mask and two valves on the mask with one removed to let in room air in case your tank runs dry. It is simple enough to attach a tab to the open port if you really want the extra O2 % which i certainly would be doing with DCS or a bad CHF -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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