P-valve decon

[surfdoggi]

Does anyone have experience with using any of the peroxide based products rather than vinegar for decontamination of the p-valve? Dive Rite has Disinfectant Tablets for their CCR. I worry about the disinfecting properties and the long term effect of the acid on suit. I was wondering if this would be more appropriate.

#DRT-36-10
DuPont RelyOn Multi-Purpose Disinfectant is a broad spectrum disinfectant that is efficacious against a wide range of pathogens. With no fumes or offensive odor, the 1% working solution is non-irritating to eyes and skin on incidental contact as well as less corrosive to environmental surfaces. A peroxygen based tablet, it is dissolved in water to provide an effective disinfectant solution, which cleans and disinfects in one step.

 

[*dave*]

Not sure why the suit would be damaged by pumping vinegar through the PV assembly, especially when you do that before rinsing the suit and follow up with a fresh water flush. As for disinfecting properties.... I guess you could go as far as you like, but I haven't heard of anyone getting an infection when they use distilled white vinegar.

 

[TSandM]

Vinegar is not a very good disinfectant, especially for acid-tolerant organisms like the ones which live in urine. Probably the biggest effect you are getting when you irrigate with vinegar is the mechanical effect of washing bacteria out of the valve and tubing -- and that effect is not to be ignored! As we say in general surgery, "The solution to pollution is dilution," and irrigation is the primary tool in cleaning p-valves, too.

For disinfecting, alcohol, chlorhexidine, or peroxide are very reasonable choices. The effectiveness of an agent is related to its toxicity and the duration of time it is in contact with the organisms. Peroxide works by oxygen radicals, though, so it's probably not a good choice for contact with rubber and plastics over time, especially things like diaphragms that have to remain flexible to work properly.

 

[*dave*]

Alcohol can be pretty hard on neoprene, as well.

Lynne, can the alcohol be diluted and still be effective? At what point does it become too diluted to be effective?

 

[TSandM]

Dave, I don't have an answer to that, and I'd suspect that it hasn't been studied, simply because alcohol is so cheap.

If you have an application where you are significantly worried about alcohol affecting the materials, I'd go to a chlorhexidine disinfectant. It's a better germicide, anyway.

 

[surfdoggi]

The P-valve is made of machined Delrin, the mushroom valve is silicone and the tubing is Norprene (www.professionalplastics.com/professionalplastics/content/norprene-a60fib-data.pdf ). All of which should be resistant to the effects of both 50% HOAc and peroxide. Isopropanol as a disinfectant in the absence of heat (e.g. friction from rubbing) was demonstrated in a paper to only dehydrate the bugs and not kill them. As TSandM noted acid tolerant bugs like coliforms would be little affected but it only takes one to cause infection. With the RelyOn the system would be treated and no water rinse used, allowing good contact and residence time for anti-microbial activity. My original issue was/is the effect of the acid on the butyl rubber and nylon of trilam suits. I guess if you treat with HOAc and flush the P-valve, then rinse the whole suit any effects would be minimized. But just treating and and flushing the P-valve leaves acid on the suit material. I don't know what the properties of chlorhexidine are, I'll have to investigate that further.