Creating rock salt in a BC

[SDAnderson]

I'm in the upper Midwest and have seen these crystals many times over the years in BCDs brought in for service. It has always been vacation divers getting ready for a trip somewhere warm and the gear hasn't been used since their last trip, normally a year or more ago. The crystals have always looked very much like the ones in the photo, maybe 1/4" or so to the side. Sometimes there will be a little dust but not much.

The salt crystals form where the water collects. If the unrinsed BC is hung with salt water in the hose, that's where you'll find the crystals. Usually the largest concentration are found at the bottom of the bladder, however.

There have been a couple that had pinhole leaks in the bladder and we've replaced a fair number of LP inflators that were badly corroded. Normally, after a good soak and flush, the BCD will operate normally and won't leak.

 

[Lee Taylor]

I typically do a complete BC bladder cleaning once a year on my personal BC. I usually find quite an accumulation of rock salt. As one would expect, it attacks any metal parts within an inflator system that are not rust proof. Moral of story: It pays to inspect and observe.

 

[bleeb]

Seawater has a salinity of about 3.5%, so 35 grams of salt per liter of water. If you have 5 grams there the prior owner left 142 milliliters of seawater to evaporate in the bc. Maybe he neglected to rinse it on the last dive, or incompletely rinsed it on several, as you might expect if it was rental gear.

From the OP's pic, there's maybe around a teaspoon in the upper pile and maybe double that in the lower pile. Table salt is about 2 grams per teaspoon, so roughly speaking, we're talking something in the range of a quarter cup for the upper pile and half a cup for the other. I don't think it's unusual to get a bit of water in a BC, especially for beginners especially hard to empty them and sink, and even if they got a bit in at a time, over a bunch of dives it could build up.

 

[toddthecat]

But the bottle cap is a real puzzle.

It's for scale! The nearest thing I had at the time I had just opened the bottle

 

[toddthecat]

Perhaps you inadvertantly got involved with a drug smuggling outfit? Be wary of unexpected knocks on the door late at night...
Any chance it is a cleaning agent, crushed mothballs... or drying agent?

That actually occurred to me, but that's more because I have found people hiding drugs in very unusual places. I have the means to test it (and did). It's salt

 

[knowone]

It comes from that ridiculous hose lifting at dumb angles and keeping the inflator open for that extra five minutes after the air has left just so the instructor can see an attempt at something is being made, as opposed to simply using a shoulder dump.

I'm not busy, may apply for a Green Card or find the marrying type.
Knocked a San Diegan, "girl" back about 25 years ago. What a shame hey Mike Boswell?

 

[toddthecat]

It comes from that ridiculous hose lifting at dumb angles and keeping the inflator open for that extra five minutes after the air has left just so the instructor can see an attempt at something is being made, as opposed to simply using a shoulder dump.

These BCs don't have that. They utilize pneumatic valves and have a separate hose with a check valve for oral inflation.

 

[Madacub]

Perhaps you inadvertantly got involved with a drug smuggling outfit? Be wary of unexpected knocks on the door late at night...

I just can't see how that much salt could accumulate inside a hose. Each subsequent dive should have (at least partially) re-disolved any salt accumulations from previous dives... It'd be hard for a large volume to build up. Also, it would highly unlikely to re-crystalize into the large lumps shown in your photo. I've been on trips where there was no fresh water to rinse BCDs for weeks on end. What accumulates is more like dust or powder... never large crystals.

Any chance it is a cleaning agent, crushed mothballs... or drying agent?

I kind of agree with Andy. At least on the part about how come it accumulated in the hose? Maybe the hose was kinked when it was hung to dry. But that would not account for such a lot of salt crystals in the hose. I'm not doubting what you found, but it seems like a very unusual set of circumstances would have occurred.

Anyway, very interesting and practical thread, thanks. So here's my question: I had thoroughly washed and dried my BC. Then 7 months no diving :depressed:. Then 3 dives and BC was well rinsed (okay, medium well rinsed!) then 3 more dives next day. No rinsing this time. Because I expected to dive the next couple of days, but got two days of bad weather. But I did drain the seawater pretty thoroughly before packing, for which I tend to fold the BC up. One week at home and heading out on another trip in 4 days :mooner:. It holds air well without any leaks right now, so it did survive the trip back.

Should I be paranoid and rinse out with fresh water right now or be lazy and repack it as it is and say "but on Scubaboard they said it was okay!"? What seems to be the customary practice amongst readers?

Thanks for your comments! (Reason for semi-paranoia: I have had to aqua seal the bladder a couple of years ago - don't know how that happened, but the 'experts' seemed to say pinch/impact puncture rather than salt crystals.)

OP: Hope this isn't a hijack.

 

[Eric Sedletzky]

I found that the best way to keep salt crystals from forming in a BC bladder is to just not use one.

 

[JimJam2]

... I have found people hiding drugs in very unusual places....

Off topic but you bring up a good point Todd; I will pack my dive log on top of my BC/Reg when traveling by air (less chance of TSA/Customs ripping my BC to shreds).
Everybody knows grandmas, young kids and divers are prone to be terrorists