Hey all, I was wondering if anyone’s knows if the older chrome plated brass SP regs exhibit the Venturi benefits without the vacuum assist switch (SP VIVA SW) to the same degree as the newer regs with the assist switch on max setting?
Scubapro chrome plated brass regulators...
- Thread starter Open Ocean Diver
- Start date
-
- Tags
- scuba regulators venturi
Please register or login
Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.
Benefits of registering include
- Ability to post and comment on topics and discussions.
- A Free photo gallery to share your dive photos with the world.
- You can make this box go away
Rusty Shackleford
Contributor
Interesting question.
They always seem to be pretty close when tuned right, my last one is gone so I can’t test the theory.
I would anticipate not, but I haven't compared one side by side... I can say that my 109s that I rebuilt and tuned myself with the bucket-0-water method breathe far easier than any rental reg I've used. Granted my experience is quite limited.
My advice is always worth what you paid for it, though... so there is that!
James
My advice is always worth what you paid for it, though... so there is that!
James
IMHO
If tuned properly only a costly testing device is going to really show a difference. Humans aren't likely to detect it.
YMMV
If tuned properly only a costly testing device is going to really show a difference. Humans aren't likely to detect it.
YMMV
halocline
Contributor
I guess the comparison would be a balanced/adjustable (or 109 balanced with the s wing poppet) compared to an early G250 with the viva vane on maximum. My experience is that it's pretty close. Maybe the G250 has slightly more venturi assist, but to be honest I have a hard time noticing much difference in the direction that vane is pointing. It definitely helps to prevent free flows with the vane on minimum.
But yes, the 109 has a strong venturi assist without the vane. This is all due to the case geometry; actually I think what the vane does is interrupt the linear flow when it's on the minimum setting.
But yes, the 109 has a strong venturi assist without the vane. This is all due to the case geometry; actually I think what the vane does is interrupt the linear flow when it's on the minimum setting.
The Apeks XTX 2nds have a fixed vane about 1/3rd from the top of the beginning of the mouthpiece at about a 40/140 degree angle.
If one had the testing equipment, it would be interesting to attach something similar to a 109-BA with (removable) loctite 222 and compare the before and after performance.
However, the regulator would be very prone to freeflow, so probably not for cold water diving and only something to consider for a primary second.
All the patents on venturi vanes mention the tendency for them to cause free flows. Apeks remedies this by redirecting the airflow towards the diaphragm. The Scubapro VIVA on minimum disrupts airflow to the mouthpiece. Atomic has some sort of automatic depth sensitive system.
If one had the testing equipment, it would be interesting to attach something similar to a 109-BA with (removable) loctite 222 and compare the before and after performance.
However, the regulator would be very prone to freeflow, so probably not for cold water diving and only something to consider for a primary second.
All the patents on venturi vanes mention the tendency for them to cause free flows. Apeks remedies this by redirecting the airflow towards the diaphragm. The Scubapro VIVA on minimum disrupts airflow to the mouthpiece. Atomic has some sort of automatic depth sensitive system.
OP
That would be a fun test...
I have a flow test bench, just tested my 156. Here’s the results:
CFM, H2O
5 - .9
10 - 1
12.5 - 1.9
15 - 2
20 - 3.9
not sure when the Venturi will kick in.
G205V @ 15 CFM VIVA min 1.9 H2O, VIVA max .3 H2O
Would be fun to installing a temporary vane to see the differences, not sure how yet.
I dive exclusively 109 or 156. I always disliked the strong Venturi effect of the G250 or similar, with the VIVA deflector. These Venturi-assisted regs make me breath more than necessary, causing an increase in my SAC, and they are less natural for me.
A properly tuned 156 (or 109 converted to BA) is what I like more, as there is perfect proportionality of your demand and the flow you get.
The increase of the breathing work is minimal, and the advantages of a more natural breathing and reduced SAC are worth such a minimal increase in the workload.
A properly tuned 156 (or 109 converted to BA) is what I like more, as there is perfect proportionality of your demand and the flow you get.
The increase of the breathing work is minimal, and the advantages of a more natural breathing and reduced SAC are worth such a minimal increase in the workload.
axxel57
Contributor
Sorry, can't confirm that.
If I test my 109/BAs on my Flow Bench, I get sometimes similar results as Overweighted with no Venturi whatsoever.
If the Venturi kicks in at all, it happens usually pretty late (at 7,5 SCFM or later) and not so 'violently', no comparison with the 'newer' models with Flow Vanes where the Crossover Flow Rate Point is sometimes below 5 SCFM and with full Free Flow
Similar threads
