The following is from the Sea Recovery water maker web site An U.V. sterilizer is recommended if the feed water (intake) is from a harbor, marina, or polluted source. The R.O. membrane rejects bacteria and viruses. However, if biological migration occurs across the membrane, then the U.V. sterilizer will destroy 99.9 % of any biological intrusion in the product water" They did state that any oil would destroy the membrane and recommended a pre-filter. (kind of obvious) I have seen these on any size yacht and is not limited to mega ones. I do see more and more yachts running dock water thru' a dedicated RO machine and then into a storage tank in addition to a second RO machiner making water from the sea. I think in the "good old days" you put about one cup of chlorine in 400 gallons of fresh water, flush the tank out and then 1/2 cup in 400 gallons and that would get rid of the rotten egg smell of old water.
So, K1W1, the manufacturers of RO systems who seel them/install them in US yachts, some equipped with a UV light --they are all breaking a rule? And, by the way, if you're going to quote someone, quote them fully. I was referring to to rules/regs in my part of the world. I'm done. Peace.
If they are selling UV as a full on primary permanent treatment for water going into storage tanks onboard I would say yes. If the UV Unit is delivered separately and designed to be in the lines that are after the pressure set and on the way to the consumer I would say no, that is how UV is supposed to be used these days Try this http://www.coastguardrescue.org.uk/c4mca/397.pdf Section 3 should cover it. Further more your Flag State and this includes the USA ( USPH)will no doubt have something very similar on record and applicable.
Since the horse apparently has not yet been beaten to death, I offer: 1) Perhaps mis-communication on my part, but I have been referring to seawater, passing through a RO machine, and then passing through a UV light, combined systems which many manufacturers offer. In our marketing-driven capitalist system, if this were against the "rules", why would they offer something illegal? And, why would I have seen this in so many engine rooms? 2) If you will kindly turn to your MCA book, section 3.4, page 13, as you kindly supplied, you will note: "Although the sterilisation process is instantaneous, ultra-violet steriliser units have no dispersal or residual properties. For this reason UV treatment is generally used only as a supplementary system, fitted downstream of the water tank or supply pump. UV units may however be effective in certain cases where service lines are relatively short..." K1W1, it is unusual for you and I to be at loggerheads on tech issues. Is there something I am missing here? Cheers
It reads to me like KIWI is saying, that in order for it to be proper to the rules, it has to be after the water tank......in other words between the water tank and the faucets/showers/ice maker etc. UV doesn't have any chemicals to prevent any growth in the water tank or residual, so in order for it to be effective and to the rules, it should be between the water tank and end use...........so what you're seeing a UV light would indeed kill bacteria from the RO watermaker and going into the tank, it still can and will grow bacteria in the tank. So this setup would not be legal in an MCA boat, it could be sold to non-inspected vessels and private yachts and that seems to be their target market.
Hi, CaptJ has understood what I was trying to say. Loren, Here is the whole section extracted from the MGN which was first posted by Marmot. You omitted an important statement just after the bit you extracted. Although the sterilisation process is instantaneous, ultra-violet steriliser units have no dispersal or residual properties. For this reason UV treatment is generally used only as a supplementary system, fitted downstream of the water tank or supply pump. UV units may however be effective in certain cases where service lines are relatively short. They should be installed so that the direction of flow is vertical to keep deposits in the tubes to a minimum. The water should be continuously circulated in the system through the UV unit. There should be a means to measure the intensity of UV radiation. and a switch-off mechanism with an alarm should be fitted in the event of UV radiation being too weak. The performance of the tubes should be regularly monitored.
K1W1 Just as an FYI. Sea Recovery market units that are bolted onto their RO units treating the product instantly even on boats with silver sterilisers and UV treatment after the hydrophore pumps as we're used to. Its a great way of getting an owner/captain to part with a bit more cash after all. Readers of this thread should not think that such a UV treatment immediately after the RO fulfills any role regarding class rules or adding to the safety of the water in any substantial way.
No, it's a good way to prevent an Algae farm from growing in your freshwater tank that the silver sterilizers and uv treatment after the hydrophore pumps would have to deal with and try to steralize. When I get back from the Bahamas, the first thing I do is dump all of the water in the water tank, and fill the water tank with city water to help prevent this.
Hi, Silver Ion Sterilisation is used in the filling line to the FW Tanks where either RO Plant or dock water passes thru. UV is used after the FW Pumps where the water goes off to the end user.
