Setting Up Cascade

[Tracy]

I'm thinking that old cascade systems that one comes across have brass pigtails and connections. Isn't brass cheaper than SS? Is there some advantage to using SS over brass? (Maximum service pressure, maybe? Or longevity?)

rx7diver

HP brass tubing is considerably more expensive than stainless of similar pressure rating.

 

[rx7diver]

HP brass tubing is considerably more expensive than stainless of similar pressure rating.

Ah, this could explain it! Thanks. Those older cascade systems are typically 3,500 psig service pressure systems. Newer cascade systems are 4,500 and 6,000 psig service pressure systems. So, brass for these newer systems would be much more expensive than SS, relatively. Correct?

Also, I think I recall reading (somewhere) that if you want your (newer) cascade system to contain higher-FO2 Nitrox, you should use SS. Does this seem correct?

rx7diver

 

[happy-diver]

What's tungum

 

[Tracy]

Ah, this could explain it! Thanks. Those older cascade systems are typically 3,500 psig service pressure systems. Newer cascade systems are 4,500 and 6,000 psig service pressure systems. So, brass for these newer systems would be much more expensive than SS, relatively. Correct?

Also, I think I recall reading (somewhere) that if you want your (newer) cascade system to contain higher-FO2 Nitrox, you should use SS. Does this seem correct?

rx7diver

Brass and oxygen typically play nice together, in my experience, it is just a cost issue. 1/4 stainless tube rated to 6k is around $1 per foot. Brass is closer to $6 and only rated to 3000. You might be able to get higher pressure brass, but I haven't seen it.

 

[-JD-]

For check valves would these work?: Stainless Steel Inline Check Valves - NPT (IPS) Threaded Ends.

6000psi WOG, 316SS, Sealed/Seated with Viton O-rings, ~$25 in 1/4" NPT (1/8" to 3/4" available)

They've been in my bookmarks for a while with another project in mind ...

 

[rx7diver]

What's tungum

This is my first time hearing about this stuff. Just spent a bit of time googling and learning. Thanks.

rx7diver

 

[rjack321]

For check valves would these work?: Stainless Steel Inline Check Valves - NPT (IPS) Threaded Ends.

6000psi WOG, 316SS, Sealed/Seated with Viton O-rings, ~$25 in 1/4" NPT (1/8" to 3/4" available)

They've been in my bookmarks for a while with another project in mind ...

Yes but not for long. You want a teflon seat not a viton seat. The SS ball in check valves basically vibrates back and forth constantly and smashes the viton to a pulp. Teflon is more of a solid and lasts longer.

 

[Miyaru]

I'm trying to figure out a way to add solenoids to the coalescers for less than commercial prices, I just need to add them to a timer. I would like to be able to walk away from my compressor for an hr or 2.

You need the control unit for automatic drainage? DIY: click

If you need solenoids - there's only 1 that releases the pressure after the first coalescer. Because of the pressure drop, the valves of the other coalescers will open as well. Of course you can add a solenoid for each coalescer.


Completely different question:
Does anyone have a automated setup for continuous blending? (EAN up to 40%)
I'm looking for a motorized needle valve, oxygen compatible.

 

[RickyVR]

If you plumb the banks to include what they call a double loop you can fill the cascade at the same time as you fill your tanks without loosing topping pressure in the cascade. This involves installing one way valves on the fill input side of the cascade from compressor (first loop) and then an on/off valve for each cascade bottle on the output side of the cascade (2nd loop) used to fill the scuba tanks.

 

[MaxBottomtime]