Mailing List Archive Mailing List Archive
I have been trying to get hold of the Sherwood 'Genesis' manifold for use in Britain. The problem I came up against was one of thread compatibility. I think the 'Genesis' manifold is unique in allowing two regulators to be fitted to a twinset so that either regulator can access the air in both cylinders. In the event of a regulator free-flowing, it can be closed off but the other regulator can still access the air in both cylinders. Questions... Am I right in thinking that only the 'Genesis' manifold offers the redundancy described ? Other manifolds I have seen either... combine the air in both cylinders to one or two regulators (a free flow results in all air being lost..!)..or have two seperate cross flow valves, so that shutting off a free flowing regulator takes that cylinder away from availability. As far as I can see, only the 'Genesis' has the extra 'cross-over' valve in the middle to make full redundancy possible. This would appear to be better than simply fitting two regulators independantly to two twin-backpack mounted cylinders. The 'Genesis' manifold is sold in the USA with a 3/4" NPSM thread. All British cylinders are sold either with a metric M16 thread (TOTALLY different to 3/4"NPSM) or with a 3/4" BSP thread. The 3/4" BSP has the same thread pitch, core dia., and outside dia. to the 3/4" NPSM and so it WILL fit. The problem is that the angle of the threads is slightly different and the root of one thread is radiused, whilst the other is flat. Getting a proper seal isn't a problem as the o-ring does this. However, I have been advised that problems will occur when getting the cylinder past its test. Fitting a thread guage to the cylinder and the manifold will show up the diference and will be attributed to 'excessive wear'. Importing USA cylinders is prohibitively expensive and I have been advised that getting these tested might cause difficulties over here too. Any signs of Sherwood manufacturing a M16 option ? Even if they would sell me a blank manifold, I could get it machined myself to M16 (re-chroming the brass after machining might be tricky..) I have heard of other Brits using the 'Genesis' manifold... a number have been sold over here. I am interested to hear how anyone else has gotten around the problems I have come up against..... A more general question to other 'Genesis' users...How easy is it in practise to shut off a free-flowing regulator and open up the cross-over valve ? I am not a contortionist and with a drysuit + all the other 'paraphanalia' of cold water deep diving I imagine it might be pretty well impossible to reach over the back of my neck to turn the two valves off/on. I also imagine a fair amount of mental effort (at depth) would go into working out which way to turn each valve. Is this a real problem..or trivial with practise ? Regards, Steve M. ******************************************************************************* * * * * Dr. S. G. Millard * E-Mail : ec96@li*.ac*.uk* * * * * * Department of Civil Engineering, * Tel : 051 794 5224 (UK) * * University of Liverpool, * 44 51 794 5224 (Inter* * PO Box 147, * * * Liverpool L69 3BX, * Fax : 051 794 5218 (UK) * * UK. * 44 51 795 5218 (Inter* * * * *******************************************************************************
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]