By Johnny Seccombe
Tim Keister’s article (April 2008) highlighted a number of important myths and misconceptions in the field of Non Chemical Devices (NCDs) as they have been applied to boilers and cooling tower treatment. Personally, I can’t claim 30 years in the business, but I have a solid 14 years of treating domestic / drinking water services, mostly in the UK. Over that time, my team has endeavored to distinguish between scientifically ‘proven’ data, field measurements and pure guess work.
Keister is quite right in pointing out that there are massive flaws in most of the commercial literature put out by NCD suppliers, but there are plenty of scientific papers that do show a link to the effects of zinc and iron dosing and other forms of nucleation stimuli. Busch, Katz, Coetzee, Chibowsky, Parsons, Judd et al. have all published peer-reviewed papers in this field.
There is no doubt at all, from my field experience, that NCDs or physical water conditioners, (PWCs) as I prefer to call them, ‘work’; what is still very unclear is the precise envelope within which they operate. The water composition down to the nano particle level is clearly a significant factor in how effective PWCs can be; even small changes in water quality can have quite large effects in the occurrence of scale, for example. When PWCs are applied to closed loop systems, such as primary boiler water and re-circulating cooling towers, the potential for interference from contaminants in the water is obviously much greater.
In the UK, the use of PWCs to treat domestic water services has, for many years, been standard procedure for hospitals, hotels, factories, offices, schools, etc. In homes they are now a legal requirement under the Building Regulations, in order to reduce energy losses due to scaled-up water heaters. PWCs outsell conventional water softeners at a ratio of at least 100 to one. The movement away from softeners is accelerating as building managers seek low maintenance alternatives and discover that the better PWCs on the market are capable of delivering their requirements.
PWC performance is variable and always will be, but experience has shown it to be reliable enough (in about 95 percent of installations) to meet the requirements of scale reduction.
Some of the better-performing PWCs demonstrate a softening effect by reducing levels of dissolved calcium in the water. They achieve this by stimulating precipitation in the bulk of the water, thus reducing calcium in solution. The result is partially softened hot water with some of the benefits of a conventional softener. This subject was highly controversial in the UK, but rigorous testing demanded by the omnipotent UK Advertising Standards Authority demonstrated the capability of our product Water-King (known as Aqua-Rex in the USA) in this respect. They now have no objection to Water-King being described by us in our advertising as an ‘Electronic Water Softener that retains the healthy minerals’.
UK experience using PWCs in the field that Keister describes is quite insignificant. For boiler feed and heating circuits, we at Lifescience refuse to offer a PWC solution, as in our opinion there are far too many factors at work to make any installation reliable. For cooling towers, we have found ourselves trapped between the legislative risk of failure on one side and the commercial interests of the service engineers on the other. In the UK, most maintenance of cooling towers is contracted out to specialists whose interests are best-served by supplying chemicals. There is no commercial benefit for them to reduce chemical dosage. This also applies to the swimming pool water treatment associations who don’t even bother to answer my letters!
There is plenty of field evidence to show that some PWCs are capable of removing existing scale from a cooling tower and of reducing further scaling. There are many explanations as to how this exfoliation of existing scale occurs – none of them, in my opinion, sufficiently convincing to be acceptable. However, just because there is no accepted scientific evidence for a phenomenon, that is not evidence that the phenomenon doesn’t exist. Remember, gravity existed before a recumbent Newton ‘discovered’ it. Anyone who has waded around the base of a cooling tower ankle deep in scale ‘shingle’ a couple of weeks after a PWC has been installed on it (in the correct place) needs no further proof of the product’s performance.
What is most interesting are the claims for (and Keister’s rebuttal of) the microbiological effect of PWCs. With Water-King, we found that Koi carp enthusiasts reported a significant reduction of Blanket Weed (known as Long String Algae in the USA). We sold thousands in Europe and a few in the USA for about $250 each, on the basis that if anyone was unhappy with their performance they could get their money back – no quibble. And we got a few back: some didn’t seem to work, some guys needed the money to go on vacation, but 92 percent of them didn’t come back. It’s not very scientific, but it is pretty good evidence nonetheless.
We then commissioned some research into the subject by Imperial College London, which showed there was an impact on yeast cells*. First it made them grow more rapidly, then it killed them off. Most significantly, however, these tests showed that the yeast cells became much more susceptible to biocides such as copper sulphate. This suggests that water treated with a suitable PWC requires lower levels of chemical biocide to achieve a given mortality rate than untreated water. A PWC won’t necessarily solve micro biological problems completely, but there are is scientific evidence to suggest that they can help – and thus reduce the use of chemicals in cooling towers..
Keister is right that there is not enough scientific evidence for the effectiveness of PWCs, but it is not fair to claim there is none at all. Clearly there needs to be more research, but this takes funding. Any offers?
*Biological Effects of Physically Conditioned Water by A. Goldsworthy et al. The Journal of the International Association of Water Quality Vol 33 No 7 Pergamon
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