Sorb-how much bouncing around in car is bad for packed scrubbers?

[broncobowsher]

I suspect a lot will have to do with how well packed the scrubber was to start with. When I was taught to pack my rEvo they are solid. You shake them and make sure there isn't any rattling inside.

Next would be the ride itself. Sitting on the passenger seat is a nice smooth ride. That is where a car is engineered to be smooth at. Now the bed of a pickup, that is bolted solid to the chassis. No rubber cushions (body mounts). That isn't engineered to be smooth. Tons of vibrations will pass through. Is your drive down a billiards table smooth road, or a washboard dirt road?

I remember when I first got the rebreather (it may still have been during the training class) someone showed up to the boat with a rebreather and decided to check the sorb in the parking lot. It had settled in the drive over and they topped it in the parking lot. I don't remember the brand, just they used a golf ball to plug the inner port during the top off.

 

[arew+4]

No actual re-breather experience, but tons with particle size, particle size distribution, ion exchange resin, and other filter media beds. That said is there a spec for particle size on sorb? How about other distribution factors stdev, span, d50, etc.

If you have a broad distribution and/or a friable particle, you could experience segregation and packing cause by vibration over time. You would end up with large spaces between large particles on the high side and tightly packed mixed particles on the low side. This would effectivity reduce the working surface area of the sorb. It may seem to be tightly packed, no rattling etc. but could be far less effective

 

[Raphus]

Interesting.. I just wondered about this..

When I use a new scrubber, I try to fill it at the dive destination.
If it's a used scrubber, I open the rebreather at the dive site and shake it, listen to rattling particles.
Never had an issue yet, but I imagine it can happen..

I dive a SF2. The scrubber is packed with a spring, so even if it sattels the spring is recompressing. Channeling is less likely, but can still occur ofc..

 

[telemonster]

Im pretty sure if you take a packed tight scrubber and vibrate it a bunch the sorb granules will indeed settle even more. I have noticed packed tight scrubber that I started with seemed to have a little room after tearing unit down for cleaning. That was after driving 3.5 hours to site on paved roads, diving, then driving back and unloading equipment. Unit is a prism2 which doesn’t have a spring in the canister itself. It left me more apt to fill on site.

 

[justinthedeeps]

Good chance it settles more. Didn't have issues with a few rowdy 4x4 roads yet We overpack the JJ canisters by ~200+ grams because it can easily settle 2-3+ cms. Breathing resistance seems unaffected (not actually measured though)

 

[jehle]

I’ve never seen a good answer on this. Unit is a Kiss Spirit.

I drive 1:15-1:30 each way to local dive sites. I often do one dive of about an hour. I allow three hours for one scrubber fill, so I’ll reuse the same sorb for the next weekend. I leave it uncovered to dry for about 12 hours then cover it up for the week. Scrubbers are packed tight.

Today I just felt really weird for the first five minutes of the dive, so I called it. I’m wondering if I could have had some break through/channeling. Sorb had one hour on it and close to four hours total getting bounced around in the car.

What have your experiences been?

There are too many variables here to pinpoint the reason you felt "weird"

But I would never consider reusing the same sorb that I used a week ago.
I am not familiar with the Kiss Spirit and I am relatively new to rebreathers, but my instructor would cancel my cert card if I told him I was considering diving with the same canister I used last week

 

[davehicks]

There are too many variables here to pinpoint the reason you felt "weird"

But I would never consider reusing the same sorb that I used a week ago.
I am not familiar with the Kiss Spirit and I am relatively new to rebreathers, but my instructor would cancel my cert card if I told him I was considering diving with the same canister I used last week

Your instructor may be quoting regulations to you. There is no actual problem using week old Sorb when you've done 1 hour on a 4-hour canister. The risk is that you completely loose track and exceed that 4-hour runtime. The stack time on your computer can help with this or just a scratch mark on a sheet of paper.

If you are doing long and deep technical dives, please start every dive fresh. If you are doing recreational limits diving, I don't see a problem with continuing to use a partial scrubber across several weeks.

 

[girlwithbigtanks]

Nope. Also i think marie sold her unit?

 

[Tracy]

Kind of an old thread, but I'll toss out an opinion. I have yet to find a road that jars my rebreather half as much as on the boat deck on a nasty day. They just get beat for hours and nobody gives it a second thought. If it is fully packed, it isn't going to settle any further from a long car ride.

 

[JackZwykle]

I think the most important aspect is not taken into consideration.
"Optimist says the glass is half full. Pessimist says the glass is half empty. A wise man asks - half full of WHAT?"

It's important HOW the scrubber is shaken.

We actually use the drive to tight pack the scrubbers. Roads are bad here outside of motorways, units go in vertically and secured after a light tapping, scrubbers are axial, jumping on the 50-120 minute drive packs them in a way we can't achieve with our hands.
And without hands too!

We only check them before the dive and typically tighten the springs (and we can see how much it has packed extra, it's amazing).

If the scrubber is on the side, the ride is rough and it packs tighter in the wrong direction - it can form a channel.

So position is most important. Once we discovered the unit untied itself and was travelling flat - we had to repack the scrubber by hand just in case.