Mailing List Archive

Mailing List: techdiver

Message Display

>Just two observations. Be aware the Sherwood first stage uses the "Dry Air
>Bleed" system. The intent is to prevent water entry into the first stage.
>The technique works quite well, but does release a constant stream of tiny
>bubbles and makes a faint hissing noise underwater. I have adapted to the
>noise but have had several people try to tell me I had a problem.

I cannot remember if I have ever posted regarding the Sherwood method of 
environmentally sealing their first stages, sorry if I have.  A couple of 
years ago an acquaintence of mine was diving in glacial melt lakes in 
Antartica, using Sherwood Blizzards for there supposed cold water 
performance.  In this cold water, with high air flow, the first stages iced 
over, as first stages will do.  The ice sealed the first stage air bleed 
leading to a rise in intermediate pressure that rapidly emptied the cylinder 
through the second stage downstream valve.  This happened regularly.  We 
subsequently played around with some regulators in ice slurries to see how 
they performed.  Sherwoods always did this and poseidins also experienced 
increase line pressure that lead to air release through the over-pressure 
valve in the LP hose.  Piston regulators with silicone environmental kits 
(my 15 year old Scubapro Mk 5 and an Airdive, the original flow through 
piston design) maintained line pressure quite well, only slightly elevated, 
with no freeflowing.  No very scientific, just some observations.

regards,

David Doolette
ddoolett@me*.ad*.ed*.au*

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]