Mailing List Archive Mailing List Archive
I have followed the (heated) debate concerning the isolation manifold question for some time, and with great interest. I like to consider myself a budding techie, and from the first dive with doubles I posed this question to many instructors and friends, with no good answer, only unresolved opinions. After listening to the arguements posted I have decided that the Isolation Manifold should be open, and here is why (I'll try to keep this short): First let's assume that I know something about valves (which I believe I do). Second let's assume that a valve has three positions, open, closed and throttled (throttled being anything from not quite closed to about 1 turn from open). And third let's assume we are doing deep diving. My first opinion was that the valve could be throttled and it would not make a difference. The simple difference of pressure from 3000psi to the intermediate pressure(IP) to the low pressure(LP) would keep plenty of air flowing. I even checked this in the shop by throttling my isolation valves while breathing through my reg. No problem. Even at very slightly cracked off the shut seat. Then it dawned on me that at 100ft about 4 times the amount of air was trying to flow through the orifice. 200ft, 8 times. I didn't experiment with this one, but it seems to me that the air flow could be restricted to the point of fatigue or light headedness at the least, at the most you could become, as Mr. Irvine I believe says, a stroke. Also I think that the valves were designed by the engineers to be operated underwater fully open. If someone has a contact at a tank valve manufacturer and could pose this question to a valve designer, that might be good. Anyway, those are my opinions, and I'm sticking to them! Thanks to all of you for submitting your opinions. They did help. Sincerely, Ron Franklin __________________________________________________ Do You Yahoo!? Yahoo! Auctions - buy the things you want at great prices http://auctions.yahoo.com/ -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
Navigate by Author:
[Previous]
[Next]
[Author Search Index]
Navigate by Subject:
[Previous]
[Next]
[Subject Search Index]
[Send Reply] [Send Message with New Topic]
[Search Selection] [Mailing List Home] [Home]