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Discussion of diving methods and equipment available prior to the development of BCDs beyond the horse collar. This forum is dedicated to the pre-1970 diving.
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Fibonacci
Master Diver
Posts: 110
Joined: Wed Oct 19, 2016 5:08 pm
First Name: Graeme
Location: Melbourne, Australia

Spiro Royal Mistral o-rings...

Sun Jan 28, 2018 9:21 pm

I'm in the final stages of rebuilding my Royal Mistral, now all pulled down, given a light pickle in 50:50 white vinegar and water then ultrasonic cleaning in Simple Green crystal. Came up like new :D

I finally found an English translation of the original French Spiro service manual and it lists a R6 o-ring for the removable volcano orifice... and no others.
R6 is a relatively obscure French Metric size ID 7.2mm x 1.9mm 90 Duro

So I was a bit surprised when disassembling the main block to discover another small quite hidden o-ring used to seal the pin!

The US Divers Mistral uses a -006 seal in the same place (ID 2.9mm x 1.78mm) but as all other aspects of the Royal Mistral are in Metric it is subtly different... carefully measuring the old o-ring I determined it is a R1 ID 2.6mm x 1.9mm.

ERIKS Industrial Services UK has the French R series in stock, as do Marylands Metrics in the US... has anyone else struck this issue?
https://mdmetric.com/or/frenchgb.htm
'A man can never have too much red wine, too many books or too much ammunition' Rudyard Kipling

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captain
Plank Owner
Posts: 1440
Joined: Mon Jul 04, 2005 11:32 am
Location: LaPlace, LA

Re: Spiro Royal Mistral o-rings...

Mon Jan 29, 2018 11:17 am

None of the O rings in a Mistral are critical. I just used the closest US size in my Spiro..
Captain

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