Honking Scubapro A700? Your experience?

[wausman]

I have the same Regs And I have the honking issue on the surface as well. But have not noticed bieing harder to breath.

 

[Luis H]

When I get back from Minneapolis this weekend I want to fill the tub and then test the second stage on a magnahelic at various orientations to quantify the numbers listed in my previosu post. I think they will be very close to what people percieve as the increases and decreases in inhalation due to the orientation of the reg.

After I left this morning I started thinking about trying something similar. The only problem I may have is that I only have Magnehelic in the 3 inWC and 5 inWC.

I should be able to do it with the 5 inWC, but I won’t be able to get to it until this weekend at the earliest. I just have too many other projects going on… including testing a new regulator that I just designed and built… I think you are going to like it.

If you remove the mouthpiece and add a flexible hose and an attachment to the Magnehelic, you don’t even have to inhale. Just submerge the second stage in the water to the exact same diaphragm depth and measure the pressure in the Magnehelic. The critical thing is submerging the second stage to the exact diaphragm depth while it is facing different positions.

I am looking forward to your test results. You will probably get to it before I do.
Good luck

 

[divin'dog]

Wow... tons of good techy info here. More than I can understand. Just to set my problem straight because my initial post might have been confusing... When I'm diving/swimming horizontally with the reg in my mouth, the purge button is facing down to the bottom of the ocean and the mouthpiece is facing up to the surface (in my mouth). No problem here. Breathes like a charm. But then if I bring my head up to see ahead of me, the reg breathes slightly harder. Now the purge button faces horizontal as well as the mouthpiece. My body is still horizontal so the relationship of the 1st stage regulator to my lungs is the same. The second stage is now closer in depth to the 1st stage by a few more inches (I'm just bringing my head up to look ahead and see where I'm going). I thought at first it was my imagination, but I can definitely tell it's more difficult and it happens every time. It's no big deal, just that I can tell the difference in pulling a breath because it's so noticeable to me.

If I bring my entire body to vertical (head up/feet down), I don't notice the effect I'm talking about. It only seems to happen when my body is horizontal and I'm looking straight ahead. Maybe it's just me?

 

[diver 85]

Take it goose hunting.........

 

[ps1mhd]

Normally, if you remove the cover reseat the diaphragm and replace the cover it will go away.

Do not take the cover off on the 700. You need to torque (6.6 inch-lbs?) the cover back on!
The tool cost $109.00:shocked2: so unless your a tech leave it alone or you can warp the cover.
Scubapro does have a new diaphragm you have to ask for when its serviced.
You may want to ask to see the torque driver some shop don't have them yet.

Mike


PS: ScubaTools.com
TorqueVario 5-10 in lbs
TorqueVario Torque Control Screwdriver, 5-10 inch lbs. (.2 inch increments). For use with Scubapro A700. Ergonomic molded multi-component handle, light and compact. Handle size proportioned to optimize torque range. Audible and perceptible click when the torque setting has been attained, automatically resets for next torque cycle.

SKU: 11-602-500
Price: $109.00

 

[Couv]

Wow... tons of good techy info here. More than I can understand. Just to set my problem straight because my initial post might have been confusing...

Don't sweat it DD,

Your first post was clear enough. The usual suspects agree on the honking noise, it's no problem and DA nailed the remedy.

The bone of contention is the cause of the change in breathing effort when you change the position of your second stage. (By the way, the first stage in this case is irrelevant.)

I don't want to put words into anyone's mouth, so guys, correct me if I have your side wrong. Matt and DA seem to be saying the change you sense is due to case geometry fault. Luis and I are of the opinion what you sense is the pressure differential between the second stage diaphragm and the human airway. To further complicate things, Luis is of the opinion the pressure changes are not sensed by the mouth and lungs, where I believe they are.

As I see it, CGF has no effect on inhalation resistance after the cracking pressure has been set as the exhaust valve is locked shut at the onset of inhalation. I think Luis' point of view is the same. Matt and DA feel CGF affects inhalation resistance.

We've had this debate before, and we will probably have it again…..now where are Pesky and Nemrod when you need them?

Couv

 

[halocline]

I admit that I believe that the difference in depth between the diaphragm and mouthpiece could have an influence on breathing resistance. I am convinced that it can't be the difference between lung depth (wherever you would measure that anyway) and regulator depth. This is easily proved by orienting vertical heads up, and then vertical heads down, and noticing that breathing resistance does not vary, or possibly a very small variation. Yet these positions represent the maximum difference between lung and regulator depth, at least a foot of difference.

I'm also influenced by the behavior of my D300s in contrast with conventional regs. The D series regs simply do not have the same change in breathing resistance with changes in position and regulator orientation. The relevant difference between the reg designs is the coaxial exhaust valve/diaphragm which dramatically lowers case fault geometry. So it's easy for me to conclude that case fault geometry is a contributing issue. It also makes sense to me that the internal pressure of the regulator body is limited by the exhaust valve; it's sort of a pressure release valve. When it's deeper, air pressure in the reg can be higher before flow. Once you exhale, you have essentially filled the reg body with as much gas as it can tolerate before the exhaust valve opens. So, it's intuitive to me that the reg body will have a slightly higher internal pressure with a deeper exhaust valve. Higher internal pressure "should" mean greater resistance to overcome to get the diaphragm to collapse and start the flow.

 

[Luis H]

I totally agree that the lungs don’t have the ability to feel pressure. Free divers can dive well over 100 ft in depth without feeling the effects of the pressure on their lungs. I never was able to free dive to 100 ft, but at any depth I have ever free dove to I can tell you pressure is not a sensation your lungs can perceive.

On the other hand I think we all know how quickly we feel pressure on our ears and how quickly and constantly we have to equalize. I have personally being very lucky that I must have very large Eustachian tubes and my ears equalize automatically as I dive, but I can still feel pressure differences. I actually tend to feel pressure changes while flying more than diving. I also feel it a lot more pronounced in a decompression chamber that in the water (I have been in a chamber several times during training).


BTW, Matt
Have you noticed how much closer the diaphragm on the D400 is to your inner ear than the diaphragm of your 109? That proximity stays constant in any head position as long as the mouthpiece is in your mouth.

I never actually tested a D400 with a long mouthpiece hose, but I have tested a Poseidon Cyklon 300 (and Scubapro 109). The Cyklon also has a coaxial exhaust and the diaphragm is also closer to my ear during normal diving condition, but the diameter is much larger that the D400.

I have also played in the water with regulator with faulty exhaust that I have intentionally blocked, but at the time was not actually testing anything in particular.


BTW, couv
The mirror, chair, measuring stick, etc. is not necessary. I actually didn’t have it at the time, but I think it would add a bit of a reference. I have found a mirror useful in checking the position of my double hose regulator; see how the hoses run, etc. BTW, what is the “roll of dimes” for?


I am still thinking about doing some testing in a small water container with a Magnehelic. The issue I am having is how I am going to precisely hold the regulator diaphragm at the exact same depth. With the diaphragm vertical (right side up, or up side down) it will be easy since I can rest it on a reference shelf. With the diaphragm horizontal (facing up or down) will be a lot more challenging to hold it precisely without making this into a large science project. If the diaphragm is not within 1/4” in depth from the other test possition, the results would not be as meaningful.

 

[Luis H]

Do not take the cover off on the 700. You need to torque (6.6 inch-lbs?) the cover back on!
The tool cost $109.00:shocked2: so unless your a tech leave it alone or you can warp the cover.
Scubapro does have a new diaphragm you have to ask for when its serviced.
You may want to ask to see the torque driver some shop don't have them yet.

Mike


PS: ScubaTools.com
TorqueVario 5-10 in lbs
TorqueVario Torque Control Screwdriver, 5-10 inch lbs. (.2 inch increments). For use with Scubapro A700. Ergonomic molded multi-component handle, light and compact. Handle size proportioned to optimize torque range. Audible and perceptible click when the torque setting has been attained, automatically resets for next torque cycle.

SKU: 11-602-500
Price: $109.00

That is too bad that you need a torque wrench to close a second stage. I am surely glad I have several Scubapro 109/ 156.

Being able to open a clean my second stage without special tool is IMHO a good design feature. I don’t see a big need to open it underwater as some tech divers would like to promote, but the ability to perform simple field repair is important to me.

 

[ps1mhd]

That is too bad that you need a torque wrench to close a second stage. I am surely glad I have several Scubapro 109/ 156.

Being able to open a clean my second stage without special tool is IMHO a good design feature. I don’t see a big need to open it underwater as some tech divers would like to promote, but the ability to perform simple field repair is important to me.

I agree. Scubapro went with 4 screws to make it smaller.
A screw-on cover would made it larger and heaver.
It's a trade off. Most divers never opens their regs any way.
If something happens it goes back to the shop.
I have alot of regs R190 250's TX50's. All with screw-on covers.


Mike