Scubapro 108HP

[redwinepeter]

Also sorting through a bunch of Pilot and Air1 new parts that i will advise when completed.
Some 108 + 109 in there as well. And other unknown parts that i do have part numbers for.
It was all part of what i cleared out of Airdive a couple of years ago who started in 1954 selling (believed to be the worlds 2nd) single hose regs (SEABEE).
He then became the biggest Scubapro distributor in Aust Pacific region we believe and was an active part of the designs of their 1stages as his are very similar. Even had plans of Scubapro units in his files.
He was a smart cookie but just was not interested in getting bigger than his market locally.

 

[redwinepeter]

Can anyone help with the following. I believe the covers are 108/109 but there are 2 styles.
Not sure about the small diaphragms.

My Pilot and Air 1 listing is nearly complete

 

[Couv]

I don't recognize any of the diaphragms. Hopefully someone with better resources and a better memory than I can give you more encouraging news. Perhaps those diaphragms go all the way back to the "Scuba Air" days circa 1962.

The covers: Second from the right is probably the older of the set. I think it was used when the 108 had a more "top hat" shaped diaphragm.

Have a look through Vintage Double Hose 's web site--->catalogs and manuals and you might uncover the info you're looking for:

https://personal.filesanywhere.com/ViewPlay/linkViewPlayWrapper.aspx?Path=%5CBLPEN163%5CManuals%20and%20Catalogs%5CScubapro%20Catalogs%5CScubapro%201962.pdf&MP=&FI=3502474&VT=F&RT=N&Type=F

 

[Open Ocean Diver]

Pulled out my 108HP has been stored for about a year, checked cracking still .9, nothing like breathing through a metal reg. Thanks to everyone that help me adjust this beauty.

I did a cracking effort test comparing the 108, 109 balanced adjustable, and the G260 with various ip’s, used an Aqualung ABS to verify my readings. Lol

I was thinking about my 108 spring and sure enough it’s the same as the 109 balanced adjustable spring. SP says the reason they went to air balancing was to lighten up the spring.

With a range of IPs all the way down to 50 psi they all cracked pretty much the same and none of them cracked over 2 at 50 psi other than the ABS which pegged the needle.

Other than adding an adjustment knob which I don’t use anyway who cares about air balancing what’s the benefit? Is it all marketing . Other thing I was wondering is why the unbalance 109 needed such a heavy spring? When my 108 light spring can hold back 135 psi no problem.

 

[rsingler]

Pulled out my 108HP has been stored for about a year, checked cracking still .9, nothing like breathing through a metal reg. Thanks to everyone that help me adjust this beauty.

I did a cracking effort test comparing the 108, 109 balanced adjustable, and the G260 with various ip’s, used an Aqualung ABS to verify my readings. Lol

I was thinking about my 108 spring and sure enough it’s the same as the 109 balanced adjustable spring. SP says the reason they went to air balancing was to lighten up the spring.

With a range of IPs all the way down to 50 psi they all cracked pretty much the same and none of them cracked over 2 at 50 psi other than the ABS which pegged the needle.

Other than adding an adjustment knob which I don’t use anyway who cares about air balancing what’s the benefit? Is it all marketing . Other thing I was wondering is why the unbalance 109 needed such a heavy spring? When my 108 light spring can hold back 135 psi no problem.

Your question relates to spring rate, and the dimensions of the two compartments.
The 216 used in the HP is pretty maximally compressed, and is providing a force near its maximum residual rate.
The 216 in the BA is much less compressed, and is providing much lighter spring forces.
Similarly, the heavier spring in the 109 is in a long compartment, and I would guess that the force provided to its unbalanced poppet is very close to the force provided by the "lighter" but much more compressed 216 in the HP valve.

A little measuring and test compression with a postal scale should allow you to prove that.

Storing with springs at two widely different net forces proves the advantage of the balanced valve: much less indenting of the seat over time. But you're right: once you add IP, the net cracking effort of the two valves can be the same.

 

[Couv]

Your question relates to spring rate, and the dimensions of the two compartments.
The 216 used in the HP is pretty maximally compressed, and is providing a force near its maximum residual rate.
The 216 in the BA is much less compressed, and is providing much lighter spring forces.
Similarly, the heavier spring in the 109 is in a long compartment, and I would guess that the force provided to its unbalanced poppet is very close to the force provided by the "lighter" but much more compressed 216 in the HP valve.

A little measuring and test compression with a postal scale should allow you to prove that.

Storing with springs at two widely different net forces proves the advantage of the balanced valve: much less indenting of the seat over time. But you're right: once you add IP, the net cracking effort of the two valves can be the same.

Additionally, the lever arm is significantly longer in the barrel poppet design when compared to the classic downstream valve lever arm.

 

[James79]

Other than adding an adjustment knob which I don’t use anyway who cares about air balancing what’s the benefit? Is it all marketing .

I don't bother converting 109's to Balanced, due to the fact that when tuned and attached to a balanced 1st stage they will breathe basically the same. The 2 main benefits of balanced seconds are:

1) Extended service times due to the lighter spring not creating a "set" in the seat as fast... for me this is offset by how cheap 109 seats are (I punch my own for pennies each).

2)More stable cracking pressure with varying IP's. In an unbalanced second, the spring is offsetting the IP, resulting in dropping IP causing higher cracking effort. A 109 on a MK2 (unbalanced piston) would breathe a little stiffer as the tank runs down (and IP drops). A balanced second has the poppet experiencing IP on both sides of the poppet, with the spring only giving a tiny bit of extra to hold it closed.... resulting in the cracking effort being about the same through out the tank pressure (and therefor IP range). This is negated (to the degree of the IP swing) by using a balanced 1st stage (MK5 or AL Conshelf, etc.).

Respectfully,

James

 

[Couv]

Double post.

 

[Open Ocean Diver]

A little measuring and test compression with a postal scale should allow you to prove that.

What do you think about this way of doing the same thing. May not give me a numerical value without other data point like lever length, compartment size… but would give me a accurate comparison of spring preload.

Setup to check cracking effort using the micro vacuum pump and leaving the LP hose disconnected. Raise vacuum until the valve opens at ambient then read Magnehelic gauge… wouldn’t this give me a comparison between various regs spring compression?

 

[rsingler]

Only if seats were near identical.
But it's a really smart idea!