資料：Magnetic Water and Fuel Treatment:
Magnetic Water and Fuel Treatment: Myth, Magic, or Mainstream Science?
Skeptical Inquirer, Vol. 22, No. 1, January/February 1998
Magnetic Water and Fuel Treatment: Myth, Magic, or Mainstream
Magnetic treatment has been claimed to soften water and improve the combustibility of fuels. A literature review reveals that these claims are not well supported by data.
Magnets are not just for refrigerators any more. In fact, according to some magnet vendors, magnets can be used to improve blood circulation, cure and prevent diseases, increase automobile mileage, improve plant growth, soften water, prevent tooth decay, and even increase the strength of concrete. Some of these claims are backed by experimental evidence. Many are not. This article focuses specifically on the claimed benefits of magnetically treated fuel and water.
Most magnetic water and fuel treatment systems appear to be marketed through independent distributors who sell out of their homes. An Internet search using the keywords magnetic treatment reveals dozens of independent distributor home
pages. Very few such devices are offered by national chain stores or advertised in mail-order catalogs. Possibly, the magnetic-device manufacturers sell through independent distributors to insulate themselves from some of the more exotic claimed benefits of magnetic treatment, or perhaps consumer and wholesaler skepticism has kept magnetic treatment out of mainstream retail. Regardless of the reasons, magnetic water and fuel treatment devices are not usually available at the local hardware or automobile parts supply store. This lack of wide availability has given magnetic water and fuel treatment a sort of fringe-science status in the minds of many consumers. Whether this label is deserved is the subject of this article.
Claimed Benefits and Effects 主張されているメリットと効果
The claimed benefits of magnetic water treatment vary depending on the manufacturer. Some claim only that magnetic treatment will prevent and eliminate lime scale in pipe and heating elements; others make additional, more extravagant claims. Some of the additional claims include water softening, improved plant growth, and the prevention of some diseases in people who consume magnetically treated water. Magnetic water treatment devices consist of one or more magnets, which are clamped onto or installed inside the incoming residential water supply line. Typical costs for a residential installation range from about $100 to $600 or more.
Magnetic fuel treatment devices are constructed similarly. One or more magnets are clamped around or installed inside an automobile's engine fuel line between the gas tank and the carburetor (or fuel injectors). Claims for these devices include decreased hazardous gas emissions, more complete combustion, improved engine power, longer-lasting engine components, and a 10 percent to 20 percent increase in gas mileage. Prices for automotive fuel treatment magnets range from about $50 to $300.
The distributors of these devices rarely can cite any documented test results that validate these claims. Instead, they rely on numerous testimonials, lists of corporations and municipalities that purportedly use the devices, and scientific-sounding explanations of magnetic water and fuel treatment. However, just because distributors do not cite the literature does not mean that no relevant literature exists. Published test reports and journal articles that investigate magnetic treatment are available. This article reviews the available experimental evidence for magnetic water and fuel treatment.
Magnets and Magnetism 磁石と磁気
To many people, magnets are a complete mystery. Vendors of magnet-based scams often use this ignorance to their own advantage, so a familiarity with the basics of magnetism can aid in the detection of dubious claims.
Magnetic fields are produced by the motion of charged particles. For example, electrons flowing in a wire will produce a magnetic field surrounding the wire. The magnetic fields generated by moving electrons are used in many household appliances, automobiles, and industrial machines. One basic example is the electromagnet, which is constructed from many coils of wire wrapped around a central iron core. The magnetic field is present only when electrical current is passed through the wire coils.
Permanent magnets do not use an applied electrical current. Instead, the magnetic field of a permanent magnet results from the mutual alignment of the very small magnetic fields produced by each of the atoms in the magnet. These atomic-level magnetic fields result mostly from the spin and orbital movements of electrons. While many substances undergo alignment of the atomic-level fields in response to an applied magnetic field, only ferromagnetic materials retain the atomic-level alignment when the applied field is removed. Thus, all permanent magnets are composed of ferromagnetic materials. The most commonly used ferromagnetic elements are iron, cobalt, and nickel.
The strength of a magnet is given by its magnetic flux density, which is measured in units of gauss. The earth's magnetic field is on the order of 0.5 gauss (Marshall and Skitek 1987). Typical household refrigerator magnets have field strengths of about 1,000 gauss. According to the distributors, the magnets sold for water and fuel treatment have magnetic flux densities in the 2,000 to 4,000 gauss range, which is not unusually strong. Permanent magnets with flux densities in the 8,000 gauss range are readily available. The magnets sold for magnetic fuel and water treatment are nothing special; they are just ordinary magnets.
Water Hardness 水の硬度
The phrase hard water originated when it was observed that water from some sources requires more laundry soap to produce suds than water from other sources. Waters that required more soap were considered "harder" to use for laundering.
Water "hardness" is a measure of dissolved mineral content. As water seeps through soil and aquifers, it often contacts minerals such as limestone and dolomite. Under the right conditions, small amounts of these minerals will dissolve in the ground water and the water will become "hard." Water hardness is quantified by the concentration of dissolved hardness minerals. The most common hardness minerals are carbonates and sulfates of magnesium and calcium. Water with a total hardness mineral concentration of less than about 17 parts per million (ppm) is categorized as "soft" by the Water Quality Association (Harrison 1993). "Moderately hard" water has a concentration of 60 to 120 ppm. "Very hard" water exceeds 180 ppm.
Hard water is often undesirable because the dissolved minerals can form scale. Scale is simply the solid phase of the dissolved minerals. Some hardness minerals become less soluble in water as temperature is increased. These minerals tend to form deposits on the surfaces of water heating elements, bathtubs, and inside hot water pipes. Scale deposits can shorten the useful life of appliances such as dishwashers. Hard water also increases soap consumption and the amount of "soap scum" formed on dishes.
Many homeowners and businesses use water softeners to avoid the problems that result from hard water. Most water softeners remove problematic dissolved magnesium and calcium by passing water through a bed of "ion-exchange" beads. The beads are initially contacted with a concentrated salt (sodium chloride) solution to saturate the bead exchange sites with sodium ions. These ion-exchange sites have a greater affinity for calcium and magnesium, so when hard water is passed through the beads the calcium and magnesium ions are captured and sodium is released. The end result is that the calcium and magnesium ions in the hard water are replaced by sodium ions. Sodium salts do not readily form scale or soap scum, so the problems associated with hard water are avoided.
A 1960 survey of municipal water supplies in one hundred U.S. cities revealed that water hardness ranged from 0 to 738 ppm with a median of 90 ppm (see Singley 1984). Ion-exchange water softeners are capable of reducing the hardness of the incoming water supply to between 0 and 2 ppm, which is well below the levels where scale and soap precipitation are significant.
One of the principal drawbacks of ion-exchange water softeners is the need to periodically recharge the ion exchange beads with sodium ions. Rock salt is added to a reservoir in the softener for this purpose.
A wide variety of magnetic water treatment devices are available, but most consist of one or more permanent magnets affixed either inside or to the exterior surface of the incoming water pipe. The water is exposed to the magnetic field as it flows through the pipe between the magnets. An alternative approach is to use electrical current flowing through coils of wire wrapped around the water pipe to generate the magnetic field.
Purveyors of magnetic water treatment devices claim that exposing water to a magnetic field will decrease the water's "effective" hardness. Typical claims include the elimination of scale deposits, lower water-heating bills, extended life of water heaters and household appliances, and more efficient use of soaps and detergents. Thus, it is claimed, magnetic water treatment gives all the benefits of water softened by ion-exchange without the expense and hassle of rock-salt additions.
Note that only the "effective" or "subjective" hardness is claimed to be reduced through magnetic treatment. No magnesium or calcium is removed from the water by magnetic treatment. Instead, the claim is that the magnetic field decreases the tendency of the dissolved minerals to form scale. Even though the dissolved mineral concentration indicates the water is still hard, magnetically treated water supposedly behaves like soft water.
According to some vendors, magnetically softened water is healthier than water softened by ion exchange. Ion-exchange softeners increase the water's sodium concentration, and this, they claim, is unhealthy for people with high blood pressure. While it is true that ion-exchange softening increases the sodium concentration, the amount of sodium typically found even in softened water is too low to be of significance for the majority of people with high blood pressure. Only those who are on a severely sodium-restricted diet should be concerned about the amount of sodium in water, regardless of whether it is softened (Yarows et al. 1997). Such individuals are often advised to consume demineralized water along with low-salt foods.
There is apparently no consensus among magnet vendors regarding the mechanisms by which magnetic water treatment occurs. A variety of explanations are offered, most of which involve plenty of jargon but little substance. Few vendors, if any, offer reasonable technical explanations of how magnetic water treatment is supposed to work.
The important question here, though, is whether magnetic water treatment works. In an effort to find the answer, I conducted a search for relevant scientific and engineering journal articles. I describe the results of this search below.
More than one hundred relevant articles and reports are available in the open literature, so clearly magnetic water treatment has received some attention from the scientific community (e.g., see reference list in Duffy 1977). The reported effects of magnetic water treatment, however, are varied and often contradictory. In many cases, researchers report finding no significant magnetic treatment effect. In other cases, however, reasonable evidence for an effect is provided.
Liburkin et al. (1986) found that magnetic treatment affected the structure of gypsum (calcium sulfate). Gypsum particles formed in magnetically treated water were found to be larger and "more regularly oriented" than those formed in ordinary water. Similarly, Kronenberg (1985) reported that magnetic treatment changed the mode of calcium carbonate precipitation such that circular disc-shaped particles are formed rather than the dendritic (branching or tree-like) particles observed in nontreated water. Others (e.g., Chechel and Annenkova 1972; Martynova et al. 1967) also have found that magnetic treatment affects the structure of subsequently precipitated solids. Because scale formation involves precipitation and crystallization, these studies imply that magnetic water treatment is likely to have an effect on the formation of scale.
Some researchers hypothesize that magnetic treatment affects the nature of hydrogen bonds between water molecules. They report changes in water properties such as light absorbance, surface tension, and pH (e.g., Joshi and Kamat 1966; Bruns et al. 1966; Klassen 1981). However, these effects have not always been found by later investigators (Mirumyants et al. 1972). Further, the characteristic relaxation time of hydrogen bonds between water molecules is estimated to be much too fast and the applied magnetic field strengths much too small for any such lasting effects, so it is unlikely that magnetic water treatment affects water molecules (Lipus et al. 1994).
Duffy (1977) provides experimental evidence that scale suppression in magnetic water treatment devices is due not to magnetic effects on the fluid, but to the dissolution of small amounts of iron from the magnet or surrounding pipe into the fluid. Iron ions can suppress the rate of scale formation and encourage the growth of a softer scale deposit. Busch et al. (1986) measured the voltages produced by fluids flowing through a commercial magnetic treatment device. Their data support the hypothesis that a chemical reaction driven by the induced electrical currents may be responsible for generating the iron ions shown by Duffy to affect scale formation.
Among those who report some type of direct magnetic-water-treatment effect, a consensus seems to be emerging that the effect results from the interaction of the applied magnetic field with surface charges of suspended particles (Donaldson 1988; Lipus et al. 1994). Krylov et al. (1985) found that theelectrical charges on calcium carbonate particles are significantly affected by the application of a magnetic field. Further, the magnitude of the change in particle charge increased as the strength of the applied magnetic field increased.
Gehr et al. (1995) found that magnetic treatment affects the quantity of suspended and dissolved calcium sulfate. A very strong magnetic field (47,500 gauss) generated by a nuclear magnetic resonance spectrometer was used to test identical calcium sulfate suspensions with very high hardness (1,700 ppm on a CaCO3 basis). Two minutes of magnetic treatment decreased the dissolved calcium concentration by about 10 percent. The magnetic field also decreased the average particle charge by about 23 percent. These results, along with those of many others (e.g., Parsons et al. 1997; Higashitani and Oshitani 1997), imply that application of a magnetic field can affect the dissolution and crystallization of at least some compounds.
Whether or not some magnetic water treatment effect actually exists, the further question, and the most important for consumers, is whether the magnetic water treatment devices perform as advertised.
Numerous anecdotal accounts of the successes and failures of magnetic water treatment devices can be found in the literature (Lin and Yotvat 1989; Raisen 1984; Wilkes and Baum 1979; Welder and Partridge 1954). However, because of the varied conditions under which these field trials are conducted it is unclear whether the positive reports are due solely to magnetic treatment or to other conditions that were not controlled during the trial.
Some commercial devices have been subjected to tests under controlled conditions. Unfortunately, the results are mixed. Duffy (1977) tested a commercial device with an internal magnet and found that it had no significant effect on the precipitation of calcium carbonate scale in a heat exchanger. According to Lipus et al. (1994), however, the scale prevention capability of their ELMAG device is proven, although they do not supply much supporting test data.
Busch et al. (1997) measured the scale formed by the distillation of hard water with and without magnetic treatment. Using laboratory-prepared hard water, a 22 percent reduction in scale formation was observed when the magnetic treatment device was used instead of a straight pipe section. However, a 17 percent reduction in scaling was found when an unmagnetized, but otherwise identical, device was installed. Busch et al. (1997) speculate that fluid turbulence inside the device may be the cause of the 17 percent reduction, with the magnetic field effect responsible for the additional 5 percent. River water was subjected to similar tests, but no difference in scale formation was found with and without the magnetic treatment device installed. An explanation for this negative result was not found.
Another study of a commercial magnetic water treatment device was conducted by Hasson and Bramson (1985). Under the technical supervision of the device supplier, they tested the device to determine its ability to prevent the accumulation of calcium carbonate scale in a pipe. Very hard water (300 to 340 ppm) was pumped through a cast-iron pipe, and the rate of scale accumulation inside the pipe was determined by periodically inspecting the pipe's interior. Magnetic exposure was found to have no effect on either the rate of scale accumulation or on the adhesive nature of the scale deposits.
Consumer Reports magazine (Denver 1996) tested a $535 magnetic water treatment device from Descal-A-Matic Corporation. Two electric water heaters were installed in the home of one of the Consumer Reports staffers. The hard water (200 ppm) entering one of the heaters was first passed through the magnetic treatment device. The second water heater received untreated water. The water heaters were cut open after more than two years and after more than 10,000 gallons of water were heated by each heater. The tanks were found to contain the same quantity and texture of scale. Consumer Reports concluded that the Descal-A-Matic unit was ineffective.
Much of the available laboratory test data imply that magnetic water treatment devices are largely ineffective, yet reports of positive results in industrial settings persist (e.g., Spear 1992; Donaldson 1988). The contradictory reports imply that if a magnetic water treatment effect for scale prevention exists, then it only is effective under some of the conditions encountered in industry. At present, there does not seem to be a defensible guideline for determining when the desired effect can be expected and when it cannot.
One of the claims made for residential magnetic treatment devices is that less soap and detergent will be required for washing. Compared to the claim to suppress scale formation, this claim has received little direct attention in the literature. To decrease soap and detergent consumption, the concentration of dissolved hardness minerals must be decreased. The tests by Gehr et al. (1995), described earlier, demonstrated a decrease in dissolved mineral concentration of about 10 percent. If this fractional decrease in dissolved mineral concentration is representative of that obtained by magnetic treatment, then it is unlikely that soap and detergent use will be significantly reduced. For example, given a water supply with 100 ppm dissolved hardness, magnetic treatment would only be expected to reduce the hardness to 90 ppm, assuming the results of Gehr et al. can be applied at this hardness concentration.
Is there a beneficial effect of magnetic water treatment? Perhaps.
Is there sufficient evidence of a beneficial effect to warrant spending hundreds of dollars on a residential magnetic water treatment unit? Unlikely. The understanding of magnetic water treatment must first be developed to the point where the effects of magnetic treatment can be reliably predicted and shown to be economically attractive.
Does magnetic water treatment perform as well as ion-exchange treatment? Definitely not. At present, the conventional water softening technologies are clearly much more reliable and effective. Further, the initial cost of an ion-exchange water softener (around $500) is comparable to that of many magnetic treatment systems.
Magnetic Fuel Treatment 燃料の磁気処理
Magnetic fuel treatment devices installed in automobiles are similar in design to magnetic water treatment devices. Hydrocarbon fuel is pumped through a canister containing one or more magnets or a magnetic device is clamped to the external surface of the fuel line. Magnetic treatment of fuel, it is claimed, results in increased horsepower, increased mileage, reduced hazardous gas emissions, and longer engine life.
Typically, vendors claim that either mileage or horsepower will be improved by about 10 to 20 percent. They also claim that if no improvement in mileage is noted, then the improvement must have come in the form of more horsepower. This, of course, makes it difficult for consumers to determine whether their magnetic fuel treatment devices really are working.
A literature search for magnetic fuel treatment studies revealed that such studies are practically nonexistent. I found a total of three references. Two of these (Daly 1995; McNeely 1994) were anecdotal accounts describing the use of a magnetic treatment device to kill microorganisms in diesel fuel, a fuel treatment application not usually mentioned by magnetic fuel treatment vendors.
The third reference (Tretyakov et al. 1985) describes tests conducted in which the electrical resistance and dielectric properties of a hydrocarbon fuel were found to change in response to an applied magnetic field. This report does not address whether the observed physical property changes might affect fuel performance in an engine, but it references two research reports that may contain performance data (Skripka et al. 1975; Tretyakov et al. 1975). Unfortunately, I could obtain neither report, and both are written in Russian.
My literature search search found no other credible research reports pertaining to magnetic fuel treatment.
The utter lack of published test data is revealing. According to the vendors, magnetic fuel treatment has been around for at least fifty years. If it actually worked as claimed, it seems likely that it would by now be commonplace. It is not.
Vendors of magnetic fuel treatment sometimes respond to this reasoning with hints that the automobile manufacturers and big oil companies are conspiring to suppress magnetic fuel treatment to maintain demand for gasoline. Such a conspiracy seems quite improbable. This supposed conspiracy has not managed to suppress other fuel-saving innovations such as fuel injection and computerized control.
In summary, I found no test data that support the claims for improved engine performance made by vendors of magnetic fuel treatment devices. Until such data become available, considerable skepticism is justified. At present, it seems quite unlikely that any of the claimed benefits of magnetic fuel treatment are real.
About the Author 著者について
Mike R. Powell, P.E., is a chemical engineer for a research and development laboratory in Richland, Washington.