Mk17 vs Mk17 EVO

[halocline]

SB peeps, I spend a good amount of time and money traveling to classes and tech clinics to learn about what I sell and work on.

Things I comment on here are directly taken from what I am taught. It is not in an effort to be dishonest to my customers. It is to be as helpful as I can. We (my bro and I) have had the great opportunity to meet many of the SP higher ups and engineers, they are all very passionate about diving and making great products for divers.

I believe you when you say you are only passing on sales pitches....oops I mean 'product information' from the higher ups at SP, so I will explain to you in clear terms why the bit about the rise in IP being a deliberate enhancement is ********.

1. It doesn't make the reg easier to breathe at the end of the dive. If anything, it just makes it harder to breathe at the beginning of the dive. I hope you understand that you can only tune the 2nd stage for maximum performance to the higher IP. What this means is that the 2nd stage is essentially 'de-tuned' at the beginning of the dive. This would be much more noticeable with an unbalanced 2nd stage.

2. A balanced 2nd stage compensates for changes in IP by increasing/decreasing the cracking effort through pneumatic pressure sourced from IP. (You do understand this, right?) Which means as the MK17 is so brilliantly increasing IP throughout the supply range (like 40 year old double hose regs), the balanced 2nd stage is simply diverting that higher IP and using it to increase cracking pressure.

3. There is no evidence at all that divers would benefit from 'easier breathing' at the low end of the supply pressure. If anything, the reverse would be true. On most dive profiles, the first part of the dive is the deepest, and the last part is the shallowest. Why would we need increased regulator performance on the shallower portion of the dive? The idea that divers get fatigued and possibly winded towards the end of a dive is nonsense. It's not a race or a hill climb.

4. The job of a 1st stage is to provide constant, reliable IP to the 2nd stage. An ideal 1st stage will do that at all supply pressures, and will experience very little IP drop under high demand. This is what makes the best 2nd stage performance possible.

Ok? Go tell this stuff to the SP higher ups, see what they have to say about it. While you're at it, please tell them they were wrong to abandon the D series, and ask them if they did so because too many dumb dealer service techs couldn't figure out how to work on them.

 

[buddhasummer]

Hurray for the D series...

 

[ScubaBros]

I believe you when you say you are only passing on sales pitches....oops I mean 'product information' from the higher ups at SP, so I will explain to you in clear terms why the bit about the rise in IP being a deliberate enhancement is ********.

1. It doesn't make the reg easier to breathe at the end of the dive. If anything, it just makes it harder to breathe at the beginning of the dive. I hope you understand that you can only tune the 2nd stage for maximum performance to the higher IP. What this means is that the 2nd stage is essentially 'de-tuned' at the beginning of the dive. This would be much more noticeable with an unbalanced 2nd stage.

2. A balanced 2nd stage compensates for changes in IP by increasing/decreasing the cracking effort through pneumatic pressure sourced from IP. (You do understand this, right?) Which means as the MK17 is so brilliantly increasing IP throughout the supply range (like 40 year old double hose regs), the balanced 2nd stage is simply diverting that higher IP and using it to increase cracking pressure.

3. There is no evidence at all that divers would benefit from 'easier breathing' at the low end of the supply pressure. If anything, the reverse would be true. On most dive profiles, the first part of the dive is the deepest, and the last part is the shallowest. Why would we need increased regulator performance on the shallower portion of the dive? The idea that divers get fatigued and possibly winded towards the end of a dive is nonsense. It's not a race or a hill climb.

4. The job of a 1st stage is to provide constant, reliable IP to the 2nd stage. An ideal 1st stage will do that at all supply pressures, and will experience very little IP drop under high demand. This is what makes the best 2nd stage performance possible.

Ok? Go tell this stuff to the SP higher ups, see what they have to say about it. While you're at it, please tell them they were wrong to abandon the D series, and ask them if they did so because too many dumb dealer service techs couldn't figure out how to work on them.

And you think I didn't know all that? And what dip **** cant tune a d-series, an air 1, or a pilot. I disagree with you strongly on the way you are looking at this.

As tank supply pressure drops, there is less pressure in the tank right? Everyone agrees on that one. So a reg tune doesnt need max IP at start of a dive when the cylinder has a higher force pushing air through the reg. It likes that extra boost at the end of a dive.

This is an experiment you can replicate pretty easy with most reg sets. Take a full cylider purge the second stage without holding the mouth piece to prevent free flow. And all adjustments open. It will most likely stick open. Then throw on a tank with 500 psi ish in it, hit the purge button and it won't want to free flow. Especially if the reg has a good number of dives on it.

If you don't like that example open a full tank valve about a 1/4 turn and listen to it drain slower and slower at it nears empty. Good regulators (any brand) will give you a nice easy breathe even on the last one that completely empties a tank. And almost all modern regs do.

When SP says they want the best performance at the end of a dive I believe them. Which is why SP regs IP should be set with a 500 psi supply pressure. If you think that is dumb... then don't dive with SP. Dive with a different brand you believe in.

You can stop wasting time trying to convince me I don't know about products I sell. Or about any SP product from the past. I've been dealing with this company most of my professional life, and they are good people. If they weren't or they didn't make on a whole great stuff I wouldn't sell it. Its called integrity something the dive industry has been lacking for quite some time. My brother and I are trying very hard to change that as it pertains to both training and the way people decide on gear.

 

[axxel57]

Okay, so he doesn't has the slightest clue how Diaphragm 1sts are working, what IP is and what it affects, the difference between balanced and unbalanced 1sts and 2nds, a perfect victim for SP Regulator Service & Repair Course crap......

No, you didn't know all that, and you still don't know sh...!

You might be an enthusiastic salesman and spare parts replacer, but we have it in writing that you don't have the slightest idea how the regulators are working which you are servicing.

That's not your fault, because it is not taught anymore, but in this forum are some pretty knowledgable guys who know pretty well how scuba regulators are functioniing, and Halo is one of them.

So better you start reading posts of Luis H., DA Aquamaster, awap, Halo and the other usual suspects or get yourself the literature, before keeping on making yourself a fool......

 

[eelnoraa]

As tank supply pressure drops, there is less pressure in the tank right? Everyone agrees on that one. So a reg tune doesnt need max IP at start of a dive when the cylinder has a higher force pushing air through the reg. It likes that extra boost at the end of a dive.

This is an experiment you can replicate pretty easy with most reg sets. Take a full cylider purge the second stage without holding the mouth piece to prevent free flow. And all adjustments open. It will most likely stick open. Then throw on a tank with 500 psi ish in it, hit the purge button and it won't want to free flow. Especially if the reg has a good number of dives on it.

If you don't like that example open a full tank valve about a 1/4 turn and listen to it drain slower and slower at it nears empty. Good regulators (any brand) will give you a nice easy breathe even on the last one that completely empties a tank. And almost all modern regs do.

When SP says they want the best performance at the end of a dive I believe them. Which is why SP regs IP should be set with a 500 psi supply pressure. If you think that is dumb... then don't dive with SP. Dive with a different brand you believe in.

Sigh, this is technically incorrect, almost show the lack of understanding of how regulator works. The analogy and experiment is also not an apple to apple comparison. A balanced 2nd stage performance when 1st stage can maintain its regulation will be constant. In your example 1, the different is due to the 1st stage input pressure drop out of the operation range.

A tank with 1/4 open value will drain slower as it empty because the through put is unregulated. The proper analogy is if you put a perfectly balanced 1st stage (lke Mk25) on a full tank. Open valve fully, but slightly loosen a port plug on the Mk25. The rate on this will be constant across the tank pressure until the regulation drop out. Now if you put a Mk17 through the same experiment, the drain rate will increase as tank pressure drop. Why is that necessary?

If you set Mk17 IP according to 500PSI tank pressure, what happen when full tank? Performance will be lower. If this the ideal way to design a 1st stage, SP sure didn't do it to Mk25.

I am not saying SP don't make good regulators, they do. In fact, 12 PSI change in IP isn't a big deal. But to market a design limitation as a feature then debunked, is embarrassing. I will go as far to say that even if SP want to, MK17 can't achieve the perfect balanced like Mk25 due to its air flow design.

 

[ScubaBros]

You want me to write you a tech novel on here about how piston and diaphragm regs work, cause I'd be happy to. Thats not really what the discussion is about. We are arguing engineering quirks that people either say is smart or complete bull ****.

I am obviously on SP's side here. Members here who think SP is lying or misrepresenting aspects are telling me why I'm being dumb. Thats what this has come to and that's fine.

As I keep saying, if you don't like what SP is making use something else. But I won't let you imply I don't know how a reg functions. I don't get much chance to get into that going back and forth arguing about different things each time.

As I said earlier... I check this at the time we were calling creep as I thought we were talking about piston regs having poor lock up since this thread is all over the place. Not about IP inversion issues associated with SP diaphram regs. Someone had said they experience IP creep as high as 12 psi. Or a balancing problem.... when I service these regs after an IP set at 500 psi I check again at half a tank and a full rank and just don't see that much change in IP if I do it's never more than 5. So at 3000 it may be at 140 and at 500 its at 145.

This thread has really blown up for me just wanting to tell someone an evo 17 and a 17 are equally good just buy what you want.

 

[axxel57]

Would be interesting if your SP Guru would dare to claim that they could have designed their Diaphragm 1sts in a way that the higher IP would be produced with fiull tank like with pistons 1sts and the lower at low tank pressure.

That would be finally something really innovative from SP.............

All Diaphragms 1sts I know and which have been on the market for decades have the lower IP at full tank which is technically logical, and have a higher IP at near empty tank, as all piston 1sts I know have the higher IP at full tank and the lower at near empty tank.

Man, use your brain.......

 

[ScubaBros]

And I have said nothing contrary to that.

 

[axxel57]

Inverse IP is actually done on purpose with SP diaphragm regs. The idea is that 2nds get a performance boost at super low tank pressure. Believe it or don't believe it. But it does make sense.

Well, okay, then my English seems to be simply too bad..........

 

[ScubaBros]

Yes in the context of the reply... the reg in question was being called a bad design for balance issues. I was saying the inverse IP is done on purpose. Do other similar regs have similar IP inversion obviously yes.