Mirada Valves

Freediver · 30 October 2015, 08:00

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Hi, does anybody have any insight as to why some of the FC line of Mil Spec Zodiacs e.g. FC530 have the Mirada valves. I was under the impression that the I/C Valves used to inflate the craft had an overpressure relief feature. If that is the case why the need for another 4 or 5 OPV's?
Thanks

office888 · 30 October 2015, 13:05

Quote:

Originally Posted by Freediver

Attachment 109483
Hi, does anybody have any insight as to why some of the FC line of Mil Spec Zodiacs e.g. FC530 have the Mirada valves. I was under the impression that the I/C Valves used to inflate the craft had an overpressure relief feature. If that is the case why the need for another 4 or 5 OPV's?
Thanks

The IC valves are very imprecise as OPVs... the OPV feature is moreso for short durations of overpressure, say, when two vessels collide at speed or after launching the boat over a wave and smacking in to the water.

The Mirada OPVs are finely adjusted and have a tolerance of about +/- 0.5 psi. They usually start to lift at about 3.1 psi or so if they're old. They're designed to be trusted as "when they start letting air out, the boat is at the proper pressure".

Freediver · 30 October 2015, 17:46

Thanks for the response, this helps. The FC 530 I have has a few of these Mirada valves. Do you know if they are factory set?
Thanks
FD

office888 · 30 October 2015, 18:00

Quote:

Originally Posted by Freediver

Thanks for the response, this helps. The FC 530 I have has a few of these Mirada valves. Do you know if they are factory set?
Thanks
FD

The valves are set at the factory at Mirada, then sold to Zodiac. The spring tension may decrease with age though, requiring replacement of the valve assembly.

The only way to know for sure is to inflate your boat with a gauge and see if the OPV opens early. If it does, replace the OPV.

cgoing · 31 October 2015, 00:53

The Mirada valves are manufactured in many different pressure setting which are much more refined as "office" pointed out. I do no have my manual handy but the ones in your boat are probably the 3.5-4 psi setting. It may say right on them.

Freediver · 31 October 2015, 02:04

Thank you, cgoing, I will check it out. And yes, you are correct, I contacted Mirada and noticed there were many different settings for the valves. Since the boat is to be inflated to 3.4mb I thought the Mirada might be a good way to adjust the springs in the I/C valves as I noticed they were releasing air around 2.9 mb. Might have to tighten the springs a little. Thanks for all the info.
FD

Freediver · 31 October 2015, 02:05

Thanks office, good info.
FD