Cold water regulator freezing question ...

[RJP]

I have been looking at the XTX200 as well as the AL Legend LX. For some reason, my LDS is pushing the MK25 over the MK17 ... so many choices and opinions, it can make your head spin.

I dive AL Legend LX Extremes in NJ year round, never had a problem.

 

[a22shady]

Best thing to do is try out each one in a pool. They will each feel/breath a little differnt and you could probably make some pros/cons for each one. Any of those mentioned above are excellent regs and will work well
MK17/G250V
Atomic M1
Apeks XTX200
Aqualung Legend Supreme
Hog Reg's

I would feel confident diving with any of those. Its really personal prefrence.

 

[rjack321]

and humidity the venturi may develop an icing condition causing the free flow.

Breathing gas is frequently wetter than it should be which is a significant source or free flow issues as well has heavy breathing at depth.

Normal specs are 24ppm or -65degF dew point and this is "ok" if its actually met by the fill station. But for ice diving the drier the better. Ambient humidity on the surface is totally irrelvant.

 

[halocline]

To erase any doubt I am a Scubapro Certified Tech...... the issue is the design itself focused on with certain atmospheric conditions water temp, air temp and humidity the venturi may develop an icing condition causing the free flow.

Bottom line is the 17 is specifically designed for extreme conditions and may breath a little drier

Please educate me on the venturi in the MK25 you're referring to and on how a particular 1st stage (the MK17) can "breathe drier" than another.

 

[halocline]

I'll be diving in the North East (NJ and NY) late spring through early fall. For this time frame, should I be concerned with purchasing a reg that performs well in cold water (i.e. SP MK17 vs. MK25), or is water temp not really an issue and should buy a better breather (i.e. SP MK25 vs. MK17)?

Who told you that the MK25 is a "better breather" than the MK17? It's not true. Put the same 2nd stage on them and you'll never tell the difference.

The MK25 has a mixed reputation in cold water. On one hand, it has been used for thousands of cold water dives without problems, and on the other you do hear about it freezing in extremely cold water fairly frequently. So, the decision is yours. If you're talking about sub 40F water, it's probably a better idea to go with the sealed MK17.

 

[Puffer Fish]

Who told you that the MK25 is a "better breather" than the MK17? It's not true. Put the same 2nd stage on them and you'll never tell the difference.

The MK25 has a mixed reputation in cold water. On one hand, it has been used for thousands of cold water dives without problems, and on the other you do hear about it freezing in extremely cold water fairly frequently. So, the decision is yours. If you're talking about sub 40F water, it's probably a better idea to go with the sealed MK17.

I've use a MK25/250V in 38 degree water and it worked fine, but I would agree with you that the MK17 is a better choice. I think really tiny effects make a difference here, so it does not surprise me that one person might have success with a MK25 and another not.

 

[ScubaSteve]

I do not think anybody will say the MK25 is a bad 1st stage......but I also do not think anybody would say you run less risk of free flowing diving an MK17 in cold waters than an MK25. The choice really is yours. Just buy whatever you buy for the right reasons and not because the LDS is pushing it on you.

 

[scuba393]

Who told you that the MK25 is a "better breather" than the MK17? It's not true. Put the same 2nd stage on them and you'll never tell the difference.

The MK25 has a mixed reputation in cold water. On one hand, it has been used for thousands of cold water dives without problems, and on the other you do hear about it freezing in extremely cold water fairly frequently. So, the decision is yours. If you're talking about sub 40F water, it's probably a better idea to go with the sealed MK17.

A response to Mattboy, benchtests show the MK25 to be a better breather. However, just because numbers on paper show one thing, doesn't mean you or I can tell a difference in real life diving.

 

[halocline]

A response to Mattboy, benchtests show the MK25 to be a better breather. However, just because numbers on paper show one thing, doesn't mean you or I can tell a difference in real life diving.

What ever bench tests you're talking about do not show the MK25 to be a "better breather." They might show higher maximum flow, but 1st stages are not responsible for inhalation effort, unless there's something seriously wrong with them, or, in the case of unbalanced 1st stages, unless supply pressure drops to the point at which IP is lowered enough to effect a cracking effort change in the 2nd stage.

Higher maximum flow in the MK25 has no effect on real world performance. The tank valve and the 2nd stage are both capable of moving far less air than the 1st stage.

I believe you're confusing 1st stage and 2nd stage issues, like the "certified scuba pro tech" has in his post.

 

[akscubainst]

I too am a certified Scubapro Tech and I totally disagree, If I have my choice of Scubapro regs I'm going to take the MK25 every time.

The MK 17 is a great reg but I can't tell you how many times I've had a student point to their MK17/s550 and show me that it was starting to trickle air. in other words build up ice in the 2nd. The solution is to shutdown the gas and let the 2nd warm up then it will go fine. All the while I'm sitting there breathing fine on a MK25/S600 more than likely sharing gas with them.

We did have some problems with mk25's initially but it's been years since I've had someone complain about a MK25 freeflow.

If you take a MK25 straight out of the box to cold water you will probably have a problem. GO read the technical documents and you will see that there are adjustment procedures for cold water. When I sell a new reg it goes straight to the bench before going out the door.

Realistically, I believe the problem (if there is one) lies in the plastic 2nd stages more than the 1st stages. That cold air needs to warm up and the plastic insulates and keeps it cold. Getting rid of hose covers and adding metal is the solution. That's why I love the G250V.