1st stage/2nd stage question...

Hi - I've been using a US Divers 1st stage/2nd/octo and it's reliable and in excellent shape. My only issue is that my 2nd stage isn't easily adjustable- and it tends to free flow on occasion.

If I wanted to upgrade the 2nd stage, but not my first stage, would that matter? That is, are there "compatibility issues"? I'm on a budget and if I can continue to use the 1st stage while only upgrading the primary 2nd, that would be ideal. Any issues that I should be aware of if I were to go with a another brand? I'm thinking of getting a Mares Rover 2nd.

Many thanks...

There "are" some compatability issues. It all really depends on the intermediate pressure the first stage gives off. The first stage reduces the pressure from tank pressure (HP) to an IP. That's why you have LP and HP hoses on your first stage. Your HP hose goes to your SPG, while your LP hose goes to your inflator and second stages. Your second stage takes the IP (typically 120-150PSI) and reduces that farther. Your inflator uses the IP to fill your BCD.

Long story short: If your first stage gives out a "normal" IP that your second stage is compatible with, there should be no issue. An IP gauge is like $15 and a great tool to have. Any shop will have one, if you don't want to have to buy one you can use theirs.

Having said all of that: You'll be fine. Worst case is you need to adjust your cracking pressure to account for a higher or lower IP than the reg is tuned for out of the box.

You will not have any issues mixing brands other than the possibility of service issues. Most shops only service a few brands and will not touch one they don't normally service. If you choose models that your service center normally services you will not have an issue.

I do have a question on the freeflow issue you are having. If it is a large freeflow that requires you block the mouthpiece when you hit the purge button or when you submerge it mouthpiece up, that NOT a defective reg but rather a high performance reg acting as it should. Many divers mistakenly think this is a problem with the reg rather than a normal operation of a high performance second stage. The second stage has a feature called a venturi and it's job is to make breathing from the regulator easier which it does but it also causes the regulator to freeflow if it is not used properly. If your reg has a lever that is marked + and - setting it to the - position will help solve the freeflows at the expense of reg performance. The real key is to understand how the regs works and use it accordingly. Never press the purge button hard above water and always make sure you enter the water with the reg in your mouth or hold it mouthpiece down and SLOWLY tip it to fill it with water. Octos are usually tuned down some which makes it less prone to these kind of freeflows but it is at the expense of regulator performance.

Leftyjeb:

Hi - I've been using a US Divers 1st stage/2nd/octo and it's reliable and in excellent shape. My only issue is that my 2nd stage isn't easily adjustable- and it tends to free flow on occasion.

If I wanted to upgrade the 2nd stage, but not my first stage, would that matter? That is, are there "compatibility issues"? I'm on a budget and if I can continue to use the 1st stage while only upgrading the primary 2nd, that would be ideal. Any issues that I should be aware of if I were to go with a another brand? I'm thinking of getting a Mares Rover 2nd.

Many thanks...

Click to expand...

The only other comment I would make is - depending on how old the 1st stage is you may need an adapter for the new hose diameter. I just replaced a high pressure hose for an SPG and I needed an adapter for the hose to 1st stage (mine are from the 70's). So bring in your 1st stage and check the hose prior to leaving the store - if you are buying on the internet this may be an issue but a good LDS should have an adapter.

depends on your actual budget --- might want to check out the diverite Rg3 -- divegearexpress has it listed for $199.00 with both 1st & 2nd stages. It's listed as din, but a din2yoke adapter is only $20. or the 2nd stage only is listed @ 109. and you can probably use your exsisting octo (see ridge diver's post for the caveat)
DGX Regulators by Dive Rite - Dive Gear Express

i'm considering replacing my octo with that setup (since i also want to switch to DIN)

Basking Ridge Diver:

The only other comment I would make is - depending on how old the 1st stage is you may need an adapter for the new hose diameter...

Click to expand...

LP ports have not changed; they have always been 3/8" in the US. The HP ports changed to 7/16" in the early 1980s.

Some USD/AL regs (and Dacor) used 1/2 lp ports for a while...another marketing idea gone bad. On those you need an adapter (1/2M to 3/8F) or find a 1/2 hose. I use an adapter.

herman:

Some USD/AL regs (and Dacor) used 1/2 lp ports for a while...another marketing idea gone bad. On those you need an adapter (1/2M to 3/8F) or find a 1/2 hose. I use an adapter.

Click to expand...

Do these regulators have ½" ports only for the LP or did they have 3/8" as well? You can include the Oceanic Omega in the list using ½" hoses, but they only had one ½" port plus 4 of the 3/8" LP ports.

Thanks for all the insight. There's a lot of thoughtful info here and I appreciate it.

Akimbo:

Do these regulators have ½" ports only for the LP or did they have 3/8" as well? You can include the Oceanic Omega in the list using ½" hoses, but they only had one ½" port plus 4 of the 3/8" LP ports.

Click to expand...

My SEA has 1x 1/2 and 3 x3/8 with a 7/16 HP port. The Dacor Enduro I have has 3x 1/2 lp ports and 1x 7/16 HP port, no 3/8 at all.