Jetsam Baby Booster Maintenance

[teksimple]

Well, I don't have the piston with me, and I know better than to be 100% certain, so let's see what comes back after they repair it

 

[happy-diver]

These were hanging out in the ocean for seventy seven years

Brass knob, bronze nut?

 

[nickbutcher]

In the meantime, I did buy a used Haskel mini booster, and its on the way. The three [count 'em 1,2,3 FFS!] service kits needed for that thing cost more than the lightly used booster itself.

The service kits for the MSB9000 are shockingly expensive, however:

I bought my Mini Haskel in 2011 and it was already about 4 years old then. In the 14 years I've been using it, I've pulled the spool out 4 or 5 times and cleaned it up. I pulled the HP end cap off once and it was spotless inside with no visible wear. That's the only 'servicing' it's ever received.

It continues to boost to 250 bar whenever I need to go that high.

I have always driven it with clean banked diving air pumped with my own Bauer PE100 so I've never used drive gas from a cheap shop compressor. And, it's only been used for myself and a few mates but this thing isn't designed for commercial use.

If I ever need to do a full service on it, I'm sure it will be cheaper to try and find another used one. However, that day isn't likely to arrive before I'm too old and decrepit to be diving any longer.

 

[iain/hsm]

Inconel spheres? Never heard about that. Do you have pictures Very interesting.

No Problem 3000psi service pressure spheres. But from a previous post since removed it looks like I'm not allowed to show you the compressor that fills them LOL
The rubber tank boot is a tad problematic mind

 

[iain/hsm]

But from the manufacturing position its pretty straightforward.

If anyone wants to get technical or looking to manufacture its a simple process using Inconel and by welding two semi ellipsoidal or hemispherical spheres is a good way of making a lightweight thin wall pressure vessel and is acceptable even with your American special permit standards.

For transportation purposes I'm not sure with things like DOT as no pressure relief device is fitted that limits the sphere pressure to 4375psi and as the calculated service pressure would be around 3500 psi

But welding is pretty straightforward and can be done even under the straightforward American MIL 2219 standard and MIL 1595 Its a fully X ray weld construction again if for you lot its Mil 1264 Grade II together with a dye penetrant test of the joint under MIL 1907

Although for use in America the minimum wall thickness is a little different than for us lot in so far that under the design calculations for use in America the design pressure must not exceed 135,000 psi or 75% of the minimum tensile strength of the material chosen. This is good as it allows a wider range of materials to be considered than for us lot. And the pressure calculation for the wall thickness is straightforward enough albeit in inches !!! The calculation is also pleasantly simple S=PD/4tE
S is the allowable wall stress (IN PSI)
P is the Test pressure hydraulic (IN PSI)
D is the outside diameter (IN INCHES)
t is the minimum wall thickness (IN INCHES)
E is the allowable weld efficiency and as above would be for an 85 percent effective weld

There is also a heat affected zone either side of the weld line that for you lot would be calculated at six times the wall thickness and thinning due to the dished end process is also in calculation

To my mind It's a pity we cannot discuss these products more fully in forum save to ask yourself why a rebreather with all its so called technology still uses a bog standard scuba cylinder and a scuba air regulator.... Just saying.

 

[teksimple]

Are you sure? That rod looks like bronze to me

From Kim, who quotes the spec from Gordon Smith, the late great designer and manufacturer of the Jetsam Baby Booster:

HP piston (long part): polished steel
LP piston (flat part): Aluminum

 

[teksimple]

The service kits for the MSB9000 are shockingly expensive, however:

I bought my Mini Haskel in 2011 and it was already about 4 years old then. In the 14 years I've been using it, I've pulled the spool out 4 or 5 times and cleaned it up. I pulled the HP end cap off once and it was spotless inside with no visible wear. That's the only 'servicing' it's ever received.

It continues to boost to 250 bar whenever I need to go that high.

I have always driven it with clean banked diving air pumped with my own Bauer PE100 so I've never used drive gas from a cheap shop compressor. And, it's only been used for myself and a few mates but this thing isn't designed for commercial use.

If I ever need to do a full service on it, I'm sure it will be cheaper to try and find another used one. However, that day isn't likely to arrive before I'm too old and decrepit to be diving any longer.

That is really good to hear, @nickbutcher. Makes me feel better about my decision

 

[iain/hsm]

From Kim, who quotes the spec from Gordon Smith, the late great designer and manufacturer of the Jetsam Baby Booster:

HP piston (long part): polished steel
LP piston (flat part): Aluminum

And of the some 3500 different types and grades of steel and not forgetting Aluminium available to the OP it would be helpful if Kim could narrow it down a tad

 

[Agro]

@Agro this is my rebreather in the flesh, right before it was shipped to me in 2004. Allegedly this is NEDU #3. The center section's horseshoe board has been rebuilt twice, the last time by me. I have had several versions of electronics, the latest now on the way is the Tigershark. But you can see the inconel spheres in the photos here: SM1600

Looks great indeed, thank you.

 

[teksimple]

And of the some 3500 different types and grades of steel and not forgetting Aluminium available to the OP it would be helpful if Kim could narrow it down a tad

I was quoted this morning by my local machine shop to replace the corrupted 5/8" chrome plated steel piston rod. The machine shop confirmed it was not bronze. $380 plus tax. Holy crap, chrome plated steel. No wonder the pitting @Agro ! Anyway, I said ok, please replace the piston rod, but only if you can do it with stainless steel as opposed to the original chome plated steel.