Aqualung blue seat US PAT 5 746 198

[spirou]

Hello kraken is. Kraken , so let's talk here about the blue 💙 seat , gently.

Screenshot_2023-08-21-22-18-28-176 by Patrick Michel, sur Flickr


Here is the first sheet of nine of the patented that you can easily found on Google
This patented is on my titan that I buy new in 2005 , remembering I always received scrap piece and I always received used bleu seat

Enjoy

Fred

[SeaRat]

Here is a slightly different view of this patent drawing:

Aqualung Seat Patent by John Ratliff, on Flickr

You can see the entire patent here:

patents.google.com/patent/US5746198A/en?oq=5%2c746%2c198

Abstract

A movable valve member is disposed within a first stage regulator within a regulator body for receipt of pressurized gas. The movable valve member is formed of a metal having an enlarged head and an attached stem with a shoulder integral with the stem adjacent the enlarged head. Surrounding the head and extending peripherally is an elastomeric or plastic material. A support washer is pressed over the shoulder against the plastic molded surface and is frictionally engaged to support the elastomeric or plastic material. A process for making the movable valve member is also provided.

In a reading of this patent, there is one statement that is perhaps pertinent to this discussion of the seat, and the possible problems with the Kraken:

Background of the Invention

...It is a further object of the invention to provide a reinforcing washer which frictionally engages a shoulder on the stem to support the plastic material covering the head of the valve member to prevent spreading during seating and to support a biasing spring to prevent wear of the plastic material...

There is an entire history of these seats discussed in this patent, and I would suggest that we all read it to see the reason for this patent.

Thanks, Fred, for showing us this one.

John

[cg43]

Hello Fred  ,  John

Very interresting to read .
Fore me it's look like there where more problem's with this seats then came to public .


The seat is 0,02" thick polyurethan 90 shore A . Why is it so thin ?

There are two values we can use : First the Deformation model :

Press a rubberplate between two steelplates even and centric .
The pressure is the same for every part of the volumen and we have a deformation in the thicknes .
Now we press two identical rubber plates so that we have the same deformation as we had bevor with one Rubber .
Now the tension in the rubber is the halve .

Pressure model

We did the same as before , only difference with the two rubberplates we imply the same pressure .
Now we have the doubel total deformation ,the tension is the same independed of the thicknes .

What do we need fore the first stage valve ?
Do we need deformation and how much ?

Using the same pressure the thin rubber has the advantage of less deformation . And this leads to less variation in IP pressure ,
because every deformation of the HP seat is transpored to the big IP spring and influeced te IP pressure .
But if we need more deformation and have a thin rubber we only get it by hight tension .

John , you write : "There is an entire history of these seats discussed in this patent, and I would suggest that we all read it to see the reason for this patent."

It's my guess that we the customer who want to breath reg's with halve an inch cracking sucction are part off
this game. Well here it comes .
A littel less save than possibel , instead every one , two , or three year changing major parts . We do accept .

Greetings   Rainer

[SeaRat]

Rainer,

Thanks for the information. I’m looking at the patent, and see this:

…At the same time, the support washer mechanically retains and supports the plastic material on the enlarged head to prevent spreading during seating. The support washer also prevents delamination of the plastic material from the enlarged head when exposed to high pressures...

I also see this:

… Since the stem 50 must pass through the O-ring 72 during operation, to avoid binding and the possible extrusion of the O-ring 72 into the bottom of cavity or opening 92 in the spring block 38, a back-up ring 108 is utilized. Preferably the back-up ring 108 is formed of Teflon™. To provide for improved ease of movement of the stem 50 against the O-ring 72, a light lubricant can be used...

So referring to the other thread on the Kraken, I’m wondering whether the Kraken has this back-up ring? ‘Looking at the diagram of the Kraken here:

vintagescuba.proboards.com/thread/6139/kraken-hp-seat-issues?page=3

…it appears that the Kraken does have this backup ring.

John

[luis]

The Kraken uses the exact same first stage as the recent Aqua Lung Titan and Conshelf. The replaceable volcano orifice is the exact same as the Aqua Lung Titan. I use either volcano orifice interchangeably and they use a very tight O-ring fit into the body.

The first stage balancing chamber also uses the latest improved O-ring "back-up ring" (as recommended by Aqua Lung), which also matches the recommendations from "the Parker O-ring manual" (AKA the O-ring bible).

I intentionally picked a mature design with almost 60 years of history behind it (the RAM and Conshelf first stage). It is true that the seat has had some evolution, but the seat design has been stable for the at least, the last 15 years.


BTW, the description on the seat in this patent is not the same as the latest blue seat offered by Aqua Lung (look at the date on the patent). I have seen this older style seat, but they are kind of rare. I think this seat was only around for a short time.

Here is the seat description from page 5

At the juncture between the stem 50 and the head 48 is
formed a shoulder 62 having a diameter slightly larger than
the diameter of the stem 50. The shoulder 62 has a sloping
or beveled surface 64 adjacent the stem 50. The shoulder 62
holds a support washer 66 which is pressed over the beveled
surface 64 and shoulder 62. It is, thus, frictionally engaged
by the shoulder 62. One side of the washer 66 supports the
plastic molded material 60 while the opposite side supports
the biasing spring 40.

Notice that Item 60 is a “plastic molded material”. The new blue seat does not match this description at all.


What I have read is that the blue seat were developed after a lot of research about 15 to 20 years ago at the most. From what I can tell, It was in response to the issues they had with the seats in this patent.

[cg43]

Hello

I'm glad about this post from Luis .

He posted :"What I have read is that the blue seat were developed after a lot of research about 15 to 20 years ago at the most. From what I can tell, It was in response to the issues they had with the seats in this patent."

Reading the patent claims I must laugh , but ok this may be the ordinary way to write such papers .
And why shoud I say anything against a design that works great ?
They changed the design and now i feel free to tell my thoughts about some details .

A 0,02" thick wascher is pressed over a nickel plated brass .
You need a to champfer the plate not to cut into the soft brass , but this reduce the area of your press .
The wascher shoud be thicker at least near the brass .
They write the elastomer is fixed to the wascher by fricktion .
But outside the diameter of part 48 there is no force to press and now the friktion is zero .
The edges of the elastomer may move .
The problems they had with the seat could be total diverent from this points .

Greetings   Rainer

supplement: Looking at pictures of Revision Kits on  ebay I found that Aqualung had improved the details  I talked about . 

[vance]

Luis,

Do you have any insights as to the Kraken seat misalignments and failures Fibonacci described? There is a different, recent thread on the Kraken and that issue.

vintagescuba.proboards.com/thread/6139/kraken-hp-seat-issues

If you do, please comment there, since this thread was intentionally made to get away from that topic. I only ask here b/c you have replied to this thread. If you do and reply there, I'll delete this post.

[luis]

I haven’t had a chance to read that entire thread since it came out while I was on a dive trip. It is long and appears to cover several subjects.


To answer your question.

The Kraken first stage is a direct copy to the Royal Aqua Master, the Conshelf and the Aqua Lung Titan. It was very intentionally designed to use all the same exact parts, using the same dimensions and the only variation would be either a manufacturing flaw or minor manufacturing tolerances. The drawings specify fairly tight machining tolerances and very tight concentricity tolerances for the first stage. But I had no involvement on the manufacturing or the quality control.

If you are referring to the lack of concentricity between the imprint on the seat caused by the volcano orifice (as seat misalignment) that is very common on RAM, Conshelf, Titan and others. That is not unique to the Kraken. I have serviced many of those regulators (RAM, Conshelf, etc.) and the imprint is rarely concentric. That is why when a seat is removed it can never be reused. That is even addressed in Pete Wolfinger, “Regulator Savvy Book”.

I have never heard that the lack of concentricity resulted in a seat failure, just by itself, as long as the seat is not reinstalled (because it will never realign perfectly).

HP Seats can and do fail by a number of reasons. But before I can comment on Fibonacci regulator, I will have to read that thread to find out more details.


My memory is not very good, but I somewhat remember some previous discussion we (Fibonacci and I) have had on this or a similar related subject. I think there are some threads over in ScubaBoard on this subject.

It is late over here, so I will have to look into it when I have more time.

[Fibonacci]

Luis!
Good to hear from you...
I've written up a few things I'd appreciate your comments on over on the original post.