Scubapro D300 Upgrade ?

[redacted]

After hearing DA Aquamaster speak so well of the D-series regs, I picked up an old D300 just to better understand the design and give it a try. I have not even serviced it yet but a test on my pony at depth left me very satisfied with its performance. I was going to service it and upgrade to the D350 lever for the obvious mechanical advantage but that lever is no longer supported by Scubapro.

So, does anyone out there have a D350 lever they are willing to part with? I'm thinking there should be quite a few in older shops used parts bins and probably even a few new ones laying around next to the NOS blue G250 poppets (or maybe even a grey one).

Should I consider upgrading to the D400 configuration? It is not at all obvious to me, based on the schematic, what the advantage is as long as the D300/350 housing is still in good shape. Am I missing something here?

Thanks.

 

[Compressor]

The D300 is an old regulator.
I have D400 and its a fine regulator. Scubapro still makes parts for my D400 as I service it yearly. if you are going to pay alot of $$ for a D400 or D350, I would consider getting a current Scubapro reg if you want to stay with Scubapro.

 

[Couv]

The D300 is an old regulator.
I have D400 and its a fine regulator. Scubapro still makes parts for my D400 as I service it yearly. if you are going to pay alot of $$ for a D400 or D350, I would consider getting a current Scubapro reg if you want to stay with Scubapro.

You want AWAP to buy a N E W regulator?
Well, that just won't do.

 

[Luis H]

The D300 is an old regulator.
I have D400 and its a fine regulator. Scubapro still makes parts for my D400 as I service it yearly. if you are going to pay alot of $$ for a D400 or D350, I would consider getting a current Scubapro reg if you want to stay with Scubapro.

Just because something is new, it is not better.

IMHO, the over all best regulator second stage ever made by Scubapro is the Metal Balanced adjustable (followed by the D400). They haven’t made it in about 20 years. There are huge numbers of them in service and we will probably see many of them still in service long after all the new plastic ones are recycled into soda bottles.

My wife dives a D400 and she loves it. I personally don’t dive anything that new. I just haven’t seen any real improvements in the last two or three decades. Don’t take me wrong, I like new gadgets if they are functional.

 

[halocline]

The D300 is an old regulator.
I have D400 and its a fine regulator. Scubapro still makes parts for my D400 as I service it yearly. if you are going to pay alot of $$ for a D400 or D350, I would consider getting a current Scubapro reg if you want to stay with Scubapro.

Really fine advice....in fact, AWAP ought to be ashamed of himself for even thinking that old regs might be better than the latest model.

 

[redacted]

The D300 is an old regulator.
I have D400 and its a fine regulator. Scubapro still makes parts for my D400 as I service it yearly. if you are going to pay alot of $$ for a D400 or D350, I would consider getting a current Scubapro reg if you want to stay with Scubapro.

It was hard enough bringing myself to buy a plastic regulator. The differences between the D300 and D400 are minimal.

 

[DA Aquamaster]

The D300 in my opinion is just fine as is and I don't really see the need to upgrade it to a D350. THe lever is a little longer, but I don't think you'd ever notice the difference.

 

[redacted]

The D300 in my opinion is just fine as is and I don't really see the need to upgrade it to a D350. THe lever is a little longer, but I don't think you'd ever notice the difference.

That's what I was hoping to hear. Longer lever I understand. But I expect that also means more diaphram travel for the same amount of gas delivery. I don't notice much difference between an Adjustable and a Balanced Adjustable so I guess I am not too sensetive to some of these finer differences.

Thanks.

 

[halocline]

I don't notice much difference between an Adjustable and a Balanced Adjustable so I guess I am not too sensetive to some of these finer differences.

As long as you're tuning the adjustable and balanced adjustable equally, they should theoretically breathe the same at a constant IP, correct? Same size orifice/seat, same lever, and tuned equally, the downstream force counteracts the stiffer spring on the unbalanced?

 

[Luis H]

As long as you're tuning the adjustable and balanced adjustable equally, they should theoretically breathe the same at a constant IP, correct? Same size orifice/seat, same lever, and tuned equally, the downstream force counteracts the stiffer spring on the unbalanced?

Well the vacuum required for cracking open the demand valve should be the same.

The difference would be in sustaining the flow. The pressure in the balance balancing chamber will dip with the IP dip (as you notice in your other thread). In essence this will reduce the effective strength of the “pneumatic spring”. Therefore it would take a bit less vacuum to sustain the flow.

That being said some of the vacuum is assisted by the venturi effect so it may be hard to notice the difference.


Note: The balancing chamber is not really a pneumatic spring, but it kind of behaves a bit like that. Kind of like a variable self adjusting pneumatic spring.