Mailing List Archive Mailing List Archive
I approach this question of which regulator is better (Scubapro Mk15 or 20) with a little caution because I am not convinced that Nilman is a real person. My apologies in advance. However since this post is my opinion (humble as it may be) then I suggest neither regulator. Personally I believe diaphragm operated first stages are more reliable than piston operated first stages because they are more tolerant to trash, crud, deposits, etc which may works its way into the operating mechanism and tend to degrade the O-ring seal required by the sliding piston design. In addition the piston design also exhibits "stick friction" which means a slightly greater exerted force on the piston is required to get the piston to move than is required once the piston is in motion. This may cause slight oscillations or lag in the intermediate pressure delivered to the second stage (although very small). I have noted this in my Scubapro Mk 5's. A well made diaphragm operated first stage would tend to be smoother as the stick friction phenomenon is not present. A piston operated first stage generally requires two seals (o-rings) to separate the ambient environment from the air chambers. This is typically not the case with diaphragm first stages. My choice for my primary regulators and deep stage bottles is the Poseidon ODIN first stage. I use the Scubapro Mk5s on shallow bottles mainly because I have it, can service it, and a Poseidon is overkill. I prefer the ODIN model just prior to the present one (the new one has the overpressure port on the side). This regulator was designed to handle up to 6000 psi inlet pressures; it is cruising along at 3.5k. The delivered flowrate is very high. For second stages, I offer the following: I use Poseidon Odin and Cyklon 2nd stages exclusively. I'm not saying they are better, but they work for me without any problems. I think they are a bit more particular than most other 2nd stages, but I'm a Poseidon (and Scubapro) certified tech so maintenance is not an issue. I think the performance of the Cyklon falls away somewhat after about 300ft when compared to the ODIN but it hasn't done so with significant notice at depths exceeding 400ft. If you use the Cyklon 2nd stage you may want to remove the "C" ring which locks the plastic cup around the exhaust housing. This way if the exhaust diaphragm gets fouled you can unscrew the exhaust housing, pop off the cup and clean it out and not call the dive. More conventional regulators such as the Scubapro G250 and G200 also make excellent 2nd stages, although you may want to tune the intermediate air pressure from the ODIN first stage down to about 140 psi to be within the normal operating range. The G250 uses a "balanced" seat configuration which in my mind the jury is still out on. They can sometimes be a pain (every now and then I get one that takes a little extra time to get right). I prefer the G200 which is the unbalanced version; its simpler and always works. These regulators are lightweight, durable, and reliable. Remember, this is just my opinion. Doug Chapman
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]