"Scubaflow" regulators !!

[Stewart]

Hi folks,

I purchased a Scubapro Mk 25 / 600 regulator in late 2003 and am curious to know if anybody else uses this system and is experiencing the same free flow problems when water temperatures get down to around 4 to 5 deg centigrade.

I have spoken to Scubapro on the matter, who made a number of recommendations - none of these resolved the situation. The regulator is currently 'in service' but still free flows in cold conditions.

Can they really claim that this regulator is fit for purpose in cold water ?

I am at the point of selling it on as I have lost all confidence in the system.

Anyone else got the same problems ?

Stewart

[Ben Panter]

Our experiences with ice diving suggest that all regulators can be made to free flow in the wrong conditions, no matter what cost or manufacturer! The fundamental problem is that you have a massive expansion of gas which will cause ice to form on any restrictive orifices... once the orifices start to ice up, the problem feeds back, further constricting the gas flow and increasing the problem.

The key candidate (from what we've seen) is dirty filters - even a little bit of greening can make a significant difference to the size of the holes running through it, lowering the output temperature and increasing the risk of free flow. This can occur well before the reg noticably detunes in temperate conditions.

The solution we came to was that regs should be prebreathed as little as possible (in fact, with the ice diving, not at all) on the surface. Once submerged, the 4 degree C water acts to warm the first stage body and stops the buildup of ice.

To reduce the load on the reg during the dive, we stay shallow and try to make buoyancy alterations with a reg attached to a seperate first stage via a h/y-valve or twinset.

With these precautions in place we've managed to get all our dives done, even with surface temperatures at -20/-30 degrees C, with decreasing numbers of freeflows. I'm pretty sure that we've had the SP reg you mention working on dives in these conditions.

Ben

[Paul Duckworth]

Funny old thing but my Mk25/S600 has let go only twice in the two years that I have had it. Both times in Vobster in approx 5°C water. BUT... I have used it in same/similar temperature water with no problem.

On the other hand I have had no problems at all with my DS4/TX40.

[Garry Whyke]

My buddy experienced 2 free flows with his scubapro in 2003 (both dives below 40 mtrs), got fed up with it, sold it and was talked into buying a new Scubapro (think it was a MK25 not sure though). Few weeks after buying it we did a 50mtrs dive and it free flowed, p**sed off he went back to the shop, and was told that he should be diving with it on minimum on deep cold dives. So, we went off to Stoney, he turned it down to minimum and it let go yet again this time on the hydrobox.

Really p**sed off this time, he sold it and bought a 2nd Apex and has never looked back.

One thing anyway, having a free flow no longer worries him.

Surprising how things like this influence your decisions. Personally I wouldn't have one.

OHH nearly forgot. On all these dives the temp was 4-5 degrees. It appeared to be a combination of the depth and pressure which triggered the problem. Since 2004 he's been diving with two TX40's and has never had a problem.

.............. Garry

[Ben Thompson]

On the other hand I have had no problems at all with my DS4/TX40.

That's because they're luverly regs :)

2 below zero in the water, and after half an hour, the whole of the first stage is pretty much encased in a ball of ice, but no freeflows... The only trickle we had was at the beginning, and that was because the IP was too high, which was fixed in about 30 seconds!

[Paul Beal]

Two friends of mine have had exactly the same problem. Scubapro give the same advise not to breath them on the surface etc. They only occasionally actually freeflowed badly; most of the time it was a fairly gentle stream of bubbles.

Paul

[Ian@1904]

I have have had three of freeflows in four years of using mk25/s600 regs. All three have been in 4/5c of water and deeper than 20m.
There is an air flow adjustor knob that must be tweaked for the cold water. This solves the issue for me. No freeflows this winter (20 dives since start of Jan)
Generally very pleased with these regs

[johnkendall]

This is quite an interesting thread. All my regs are Scubapros, and the only time I've ever had a freeflow on one was when a little bit of stone got trapped in the purge button and locked it on. I use my regs all year round, in all temperatures, depths down to 60m and use a lot of helium too, and have never had a problem.

J

[John Bantin]

http://www.divernet.com/equipment/0501icing.htm

Scubapro now makes a very good MK17 diaphragm-type regulator.

[Adrian Kelland]

http://www.divernet.com/equipment/0501icing.htm

Scubapro now makes a very good MK17 diaphragm-type regulator.
Is Gilbert de Coriolis a French spin doctor? :)

[Ben Panter]

John,

Just a little technical note: in the article you state:

IT SHOULD BE NOTED THAT COLDWATER TESTING for EN250:2000 Cold Water allows for the water to be at +4°C, and that water at Stoney Cove in winter is often at that temperature or even less.

Although the very surface-most layer could reach less than 4°C via conduction with surface air (and hence freeze), anything further down than the top few centimeters will be at 4°C. If it gets colder, it becomes less dense (due to hydrogen bonding) and rises (convection) to form an ice sheet at the surface. I'd suggest that if lower temperatures are recorded, it's the calibration of the thermometer that is at fault, rather than a real effect. Hence it's a bit unfair to criticise EN250:2000 in that respect.

cheers,

Ben

[John Bantin]

My mission is to make people think. In this I am often controversial but I think that if readers think I get it wrong I have at least achieved getting them thinking! Thanks for the technical info. As I always say, I am not an expert. I am a witness.

I will not make fun of Gilbert's name. He has enough on his plate being French!!!

[Stewart]

Putting the Scubapro Mk25/600 to one side, anybody got any good recommendations for a good all-round alternative. I've heard good reports about the Mares Proton Ice, Aqualung LX Supreme and the Apex range in general.

I need something which is a high performer, good in cold water and reasonably cheap to service.

Stewart

[PeteM]

Putting the Scubapro Mk25/600 to one side, anybody got any good recommendations for a good all-round alternative. I've heard good reports about the Mares Proton Ice, Aqualung LX Supreme and the Apex range in general.

I need something which is a high performer, good in cold water and reasonably cheap to service.

Stewart

Apex TX40, or ATX40 or XTX40 - cheap cheerfull, bullet proof, the work horse of the UK diving scene I've got eight of them

[Garry Whyke]

Apex or Poseiden.

I use the TX40 and Jestream, and have used it faultlessly on deep dives for many years.

[Paul Morris]

I have had both, and the ATX200 as well. For me, its Apeks without doubt.

Depends how you like it: hard and deep, or soft and gentle :eek:

The Posiedon, a great timeless but arguably dated reg, is somewhat 'forceful' in its delivery ;) . Performs better at depth than shallow. Don't press the purge button with the regulator in your mouth, at risk of embolism :eek:

The Apeks has been smooth as silk. TX40 is great, my fave is the ATX200 when tuned just right I can forget I'm using a reg (at any depth). :cool:

Both top-end regs, but the poseidon is relegated to my AAS reg on the twinset. As soon as replacement time comes up, might try an XTX instead once they've been around a bit (field tested :D )as they can be rigged either side.