LarsB
Contributor
Dear divers,
I was wondering if you could help me cut this Gordian knot:
I have just started studying the book for the CMAS 3* course and I am trying to find back on the market what it teaches about regulators, because eventually I will want to buy one.
I learned about membrane- (diaphragma-) based and piston-based ones, as well as balanced and unbalanced or even overbalanced ones (= the intermediate pressure rises overproportionally with increasing depth, in order to compensate for the increasing viscosity of the air), and about the Venturi effect which reduces breathing resistance but increases the risk of free-flowing.
Another nice feature seems to be the bypass in the 2nd stage, which lowers the risk of it freezing. Exotic: the constant bleed system.
But which regulators use which technology? Their descriptions in online shops do not always tell.
What are the advantages and disadvantages of these technologies?
For instance, between membrane-based and piston-based?
In terms of reliability (safety), easy breathing yet not easily free-flowing, easy maintenance (widely available and not expensive), works great in any position (also head upside down or belly up), humidifies the air stream, and in terms of price?
(I understand that environmentally sealed membrane-based 1st stages use silicon oil and are therefore more difficult to service?)
I need a regulator which allows me to dive with (up to 40% oxygen) Nitrox and in cold water (mostly lakes, Zealand and North Sea).
From my Nitrox course I know that diving equipment must be specially adapted and certified to be usable with Nitrox.
For insurance and liability reasons, I therefore want to do "the right thing".
However, I hardly can find any Nitrox-certified regulators, even less for cold water.
I also notice that Nitrox-certified regulators are certified for up to 100% oxygen.
Isn't that overkill?
Is this one for instance suitable for my needs?
Scubapro MK25 / S555 Nitrox Atemreglerset
Apeks XTX 40 Nitrox Octopus
Subgear MINI OXI FINI 300bar Nitrox Finimeter - Seemann
What alternatives are there?
It also says there that this regulator must be serviced by a certified technician after using it with pressurized air instead of Nitrox.
Why that? Isn't pressurized air just the same as Nitrox with 21% oxygen?
Another dive shop told me that normal regulators were suitable for Nitrox (I suppose they meant for up to EAN 40?). Is that true?
For example: Aqualung Legend LX Supreme ACD Ademautomaat
(Very nice, this ACD feature which automatically closes the input of the 1st stage when dismounted from the tank!)
What regulators would you recommend?
Another, related question:
Is it true that Nitrox tanks have different ports than tanks for pressurized air, in order to prevent filling in the wrong gas accidentally?
How can they be filled with pressurized air, nevertheless? Via adapters?
Otherwise the warning above about service being required for a Nitrox regulator after using it with pressurized air wouldn't make sense, would it?
Are these ports at least standardized, i.e., are they the same everywhere, so that I can use my Nitrox-certified regulator anywhere in the world?
(I know about INT and DIN and respective adapters, so that's not the question. Or is it?)
Or aren't the ports on the regulators specific for either Nitrox or pressurized air, only the ports on the tanks? (How is that mechanically possible?)
BTW, are there any Nitrox-certified BCD's?
Doesn't the Nitrox damage the airtight/watertight inner membranes of "normal" BCD's?
Thanks a lot for all hints which might help me cut this knot!
Cheers,
LarsB
I was wondering if you could help me cut this Gordian knot:
I have just started studying the book for the CMAS 3* course and I am trying to find back on the market what it teaches about regulators, because eventually I will want to buy one.
I learned about membrane- (diaphragma-) based and piston-based ones, as well as balanced and unbalanced or even overbalanced ones (= the intermediate pressure rises overproportionally with increasing depth, in order to compensate for the increasing viscosity of the air), and about the Venturi effect which reduces breathing resistance but increases the risk of free-flowing.
Another nice feature seems to be the bypass in the 2nd stage, which lowers the risk of it freezing. Exotic: the constant bleed system.
But which regulators use which technology? Their descriptions in online shops do not always tell.
What are the advantages and disadvantages of these technologies?
For instance, between membrane-based and piston-based?
In terms of reliability (safety), easy breathing yet not easily free-flowing, easy maintenance (widely available and not expensive), works great in any position (also head upside down or belly up), humidifies the air stream, and in terms of price?
(I understand that environmentally sealed membrane-based 1st stages use silicon oil and are therefore more difficult to service?)
I need a regulator which allows me to dive with (up to 40% oxygen) Nitrox and in cold water (mostly lakes, Zealand and North Sea).
From my Nitrox course I know that diving equipment must be specially adapted and certified to be usable with Nitrox.
For insurance and liability reasons, I therefore want to do "the right thing".
However, I hardly can find any Nitrox-certified regulators, even less for cold water.
I also notice that Nitrox-certified regulators are certified for up to 100% oxygen.
Isn't that overkill?
Is this one for instance suitable for my needs?
Scubapro MK25 / S555 Nitrox Atemreglerset
Apeks XTX 40 Nitrox Octopus
Subgear MINI OXI FINI 300bar Nitrox Finimeter - Seemann
What alternatives are there?
It also says there that this regulator must be serviced by a certified technician after using it with pressurized air instead of Nitrox.
Why that? Isn't pressurized air just the same as Nitrox with 21% oxygen?
Another dive shop told me that normal regulators were suitable for Nitrox (I suppose they meant for up to EAN 40?). Is that true?
For example: Aqualung Legend LX Supreme ACD Ademautomaat
(Very nice, this ACD feature which automatically closes the input of the 1st stage when dismounted from the tank!)
What regulators would you recommend?
Another, related question:
Is it true that Nitrox tanks have different ports than tanks for pressurized air, in order to prevent filling in the wrong gas accidentally?
How can they be filled with pressurized air, nevertheless? Via adapters?
Otherwise the warning above about service being required for a Nitrox regulator after using it with pressurized air wouldn't make sense, would it?
Are these ports at least standardized, i.e., are they the same everywhere, so that I can use my Nitrox-certified regulator anywhere in the world?
(I know about INT and DIN and respective adapters, so that's not the question. Or is it?)
Or aren't the ports on the regulators specific for either Nitrox or pressurized air, only the ports on the tanks? (How is that mechanically possible?)
BTW, are there any Nitrox-certified BCD's?
Doesn't the Nitrox damage the airtight/watertight inner membranes of "normal" BCD's?
Thanks a lot for all hints which might help me cut this knot!
Cheers,
LarsB
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