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Old 06-10-2013, 01:22   #1
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A Few Questions About PFDs.

I'm in the process of trying to consolidate, update and retire the PFDs I have managed to accumulate.

The good news is that the old stuff is really obviously old (fun/scary picture attached).

The bad news is that there are too many damned inflation mechanisms that are generally incompatible with one another.

Right now, the only thing that seems to be standard is the 1/2" threads for the 33g CO2 cartridge. Although, one of the PDFs I'm retiring (West Marine SOSPenders, which I really like) had a 3/8" CO2 cartridge. All of the water-inflate mechanisms seem to be proprietary, along with the manner in which they attach to the PFD.

Anyway, due to my location (Japan) I'm having a hard time getting PDFs shipped to me due to the HAZMAT status of the CO2 cartridges Fortunately, I have found a supply of 38g 1/2" thread cartridges. Unfortunately, I have not found anyone that will ship PFDs without the CO2 cartridge.

So, my biggest question(s) is/are: will a 38g CO2 cartridge work for most PFDs? (Do they have a relief valve to blow off excess pressure? How much extra pressure with another 5g of CO2 cause or the average PDF? I'd rather not have a cartidge installed than have a cartridge that will rupture the PFD's air bladder. I guess I could always test; has anyone else done this?)

Next, I'm curious to see if there is a consensus about which PFD(s) are the best (with "best" having lots of different parameters, but for me, that would be something along the lines of longevity, comfort/wear, amount of time the water-inflate mechanism is good for, no false positives for PDF deployment for the water-inflate mechanism, D-ring for jack-line snap-in, zippered pockets and pouches for additional add-on safety gear like strobe and small handheld VHF radio.)

I am also curious to know what other equipment folks add on their their crew's PFDs. Right now, the minimum add-ons for me are strobe and whistle (if the PFD doesn't already have one). I'd like to add a small, cheap DSC capable VHF handheld, but that gets kind of expensive... maybe just one or two for deck-forward crew).

Finally, I'm looking for good sources re-arm kits (suppliers who don't ship stuff that's within a year or two of needing to be replaced). I've noticed that some of the Amazon reviews for PFDs have negative review for this reason. Case in point: Onyx A/M 24 Deluxe - Automatic/Manual Inflatable Life Jacket (PFD): Sports & Outdoors

I think, at the moment, I like the west marine Off-Shore PFD because it *lacks* a water-inflate mechanism (on the other hand the re-arming nib seems pretty flimsy... I'd like the 1/2" threads to screw into something with some substance to it). Any thoughts or comments on that?

As always, thanks for your time and collective wisdom...
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keelsidedown is offline   Reply With Quote
Old 06-10-2013, 22:02   #2
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Re: A Few Questions About PFDs.

Ok... I think I have some answers about the usability of 38g CO2 cartridges.

First, the PFD instructions have a warning about partial inflation in sub-zero temps. and explicitly warns to not over inflate because it could "over-pressurize and damage your PFD" (which pretty much sounds like a bladder rupture situation). So... I assume that means there's no relief valve to vent off over pressure.

The math behind all of this is as follows:

Xgrams/ 44grams (44 grams = one mole of CO2) = ratio that can be applied to volume of 1 mole of an ideal gas at STP

Volume of 1 mole of an ideal gas at STP is 22.1 liters (actually I've seen 22.4, but 22.1 for CO2 was referenced, so that's what I'm using)

33g / 44g = 0.75

22.1 liters x 0.75 = 16.575 liters

38g / 44g = 0.8636

22.1 liters x 0.8636 = 19.086 liters (about 15% more volume).

Anyone know if a nice PFD that takes 38g 1/2" thread cartridges? (I see west marine does sell a 38g CO2 cartridge)
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