Scale is formed when heating or evaporating hard water spoiling not only the visual perception, for example, of a bathroom but causing a number of negative consequences, namely:
Almost each of us faces the problems caused by scale formation. It is enough to provide the examples of “covering” THEs of washing machines or water heaters, formation of lime scale from water drops on the chromed mixing valves in a bathroom and in a kitchen, white film on the utensils. What is scale and why it is formed?
Scale is a hard deposit of hardness salts mainly formed by the calcium carbonate crystal structures (CaCO3). Hardness salts - calcium ions (Ca2+), magnesium (Mg2+) and bicarbonate (HCO3-) - enter the water supply system in the dissolved form from ground water and limestone artesian wells, which leads to the presence of hard water in the water system of almost all Russian geographical zones. it is assumed that using of hard water has no adverse health consequences. At the same time hard water negatively affects the water taste, assists poor foaming of washing agents and makes the skin dry.
All these methods are combined by the availability of wear components needed to be replaced regularly and/ or availability of expensive equipment. Using of reagents often has an adverse impact on ecology.
6) The magnetic water treatment as a measure of scale and corrosion control became widely known as early as in 1945 (Belgian patent No 460560 issued to T. Vermeiner).
There are devices based on permanent magnets certain placement of which along the pipe results to the impact of the variable magnetic field on flowing water.
Using if electric devices forming variable electromagnetic field is effective even for still water.
Both devices have the advantages.
The devices with permanent magnets do not require power supply.
The electric devices are easily scaled (use on pipelines of various diameters and various water consumption).
Nowadays there are some hypotheses explaining this effect. But in general they agree that the ions of the compounds dissolved in water are in hydrated shells the formation of which is subject to the fact that the water molecule is asymmetrical and possesses a dipole moment, i.e. the side of the molecule where hydrogen atoms are displaced has a positive charge and the side with the oxygen atom - a negative one and therefore the water molecules seem to stick to the ions of the compounds dissolved in water:
— affected by the variable magnetic field the moving electric charge (a water molecule has two centres with positive and negative charges) is exposed to the Lorentz force resulting in deformation and destruction of the hydrated shells of the ions of the compounds dissolved in water causing the hydration reduction and increase of the possibility of approach and aggregation;
— as the result during the reaction of transformation of the calcium hydrocarbonate dissolved in water to Са(НСО3)2 to CaCO3 and carbonic acid H2CO3 the centres of phase change of calcium carbonate are easily formed with further formation of CaCO3 crystals to water flow.
In fact during thermal water softening the hydrated shells of the ions of the compounds dissolved in water are destroyed but because of speeding of heat motion of a particles. And this happens on a hot surface (heat source) but not in the water volume.
It should seem that insufficient difference in the principle and the point of hydrated shell destruction and at the point of the reaction of calcium carbonate formation correspondingly leads to sufficient difference of the result. The fact is that the crystallized calcium carbonate has naturally some various polymorphic modifications (crystals differed by crystal lattice structure); the main ones are calcite and aragonite. The difference in the crystal lattice structure leads to sufficient difference of physical properties. Aragonite has large density and melting temperature. But the main fact is that the adhesive properties determining the capacity to stickiness and adherence to the structure surfaces are higher than those of calcite.
So while thermal softening calcite forming a scale layer is formed on a hot surface and aragonite is formed in the water volume while nucleation (formation of centres of phase changes) that occurs during (electro)magnetic treatment.
The aragonite crystals formed in the result of the electromagnetic treatment of water do not adhere to the structure walls and are washed out with flow. it is quite easy to detect their formation: just let the treated water settle in a tank (pot, bucket, bowl) and a thin white film will be formed on the surface or small white flocks will float at the bottom - they are the aragonite crystals.
Well, we have prevented the calcite formation on a heating element but there is one more effect - removing of already existing scale.
The fact is that most of chemical reactions are reversible if the substances involved in he reactions are not separated. As it was stated above calcium carbonate is formed in the result of the transformation reaction of calcium hydrocarbonate dissolved in water to Са(НСО3)2:
Ca2+ + 2HCO3- ←→ CO2(aq) + CaCO3(s) + H2O
If any free surface (contact with air) carbon dioxide formed in the result of which is escaped from water i.e. the substances involved in the reaction are separated! However if it occurs in a pipe when carbon dioxide has nowhere to go (no water contact with air) carbon acid is formed in water:
CO2 + H2O ←→ H2CO3
it is a weak acid and an unstable compound as it was stated above. But if no open surface when carbon dioxide has nowhere to escape this acid exists. And correspondingly the reaction of calcium carbonate formation may be in the reverse direction i.e. carbon acid will start dissolve already existing calcium carbonate.
Well why then we talk about removing already existing scale and boiler cleaning?! A moment ago caused by the electromagnetic field calcium carbonate and carbon acid have been formed and they should react correspondingly!
But it is not so easy. As it was stated above calcium carbonate has polymorphic modifications such as calcite and aragonite differed by their properties. And in nature calcite is more widely spread and it is due to the fact that the formation energy is less than that of aragonite. Consequently the energy of its decomposition is less as well. So carbon acid in water will firstly dissolve calcite of which scale consists but not aragonite.
Here we should note again that carbon acid is weak and the accumulated scale layer may be thick enough, so it must take quite a long time - from some days to two-three months - for the effect (obvious improvement of operation of water heating boiler). Besides much depends on used water.