Toronto Boiler Maintenance
Water impurities is the primary subject when addressing Toronto Boiler Maintenance concerns and problems. These impurities can be in either gaseous or solid form. Dissolved gases include oxygen, carbon dioxide, and nitrogen the same elements that comprise our atmosphere.
Solids are found in two forms: suspended or dissolved.
Suspended solids include any impurities in the water that are not dissolved, including sand, silt, or particles of organic matter i.e., leaves. If left undisturbed, suspended solids will settle to the bottom of a vessel or container.
Dissolved solids include any impurities that are dissolved in the water supply and comprise mainly minerals from the earth’s crust.
The term total dissolved solids is a measure of all impurities dissolved in a given water supply.
Most dissolved mineral impurities found in water are present in the form of ions, which are electrically charged particles that are either positively or negatively charged.
Ions with a positive (+) electrical charge are called cations; ions with a negative (-) electrical charge are called anions.
When dissolved in water, ions break apart in a process called disassociation. For example, calcium carbonate (CaCO3) will break apart in water to form the cation calcium (Ca++) and the anion carbonate (C03Ñ). Under certain circumstances, ions can recombine to form compounds: (Ca++) + (C03Ñ) CaC03. Water hardness is the measure of calcium and magnesium (Mg+ +) content as calcium carbonate equivalents. As the water temperature rises, calcium and magnesium compounds become insoluble. Calcium carbonate is the primary source of scale in cooling and boiler water systems.
Alkalinity is a measure of the bicarbonate (HCO3-), carbonate (CO3–), and hydroxyl (OH) ions in water. It is possible for these ions to exist simultaneously; however, only the bicarbonate and carbonate ions are found in natural water supplies.
M alkalinity, or total alkalinity, is defined as the sum of carbonate, bicarbonate, and hydroxide. P alkalinity, or phenophtalein, is defined as one half of the carbonate alkalinity plus all of the hydroxide alkalinity. Carbonate and bicarbonate alkalinities can combine with calcium and magnesium hardness to form scale in cooling and boiler water systems.
There are many other impurities found in natural water supplies. The most common are chloride, sulfate, iron, silica, sodium, and manganese.
pH is the measure of the degree of acidity or basicity of solution. The pH scale ranges from O to 14, with zero being the most acidic and 14 the most basic or alkaline. Control of pH is critical in the majority of heating and cooling systems. A change of one pH value represents a change of 10 times in relative acidity or alkalinity. For example, a pH of 4 is ten times more acidic than a pH of 5.
Cycles of concentration refers to the accumulation of the impurities in a water supply. As water evaporates, water impurities are left behind. When a cooling tower or boiler is replenished with fresh water, more impurities are carried into the system. If the system water contains twice the level of impurities in the fresh water supply, it is said to have two cycles of concentration. If the system water contains four times the level of impurities in the fresh water supply, it is at four cycles of concentration. Left unattended, the impurities in a cooling tower or boiler system increase indefinitely until the water is unable to dissolve its own impurities or hold them in solution.
The cycles of concentration in a cooling system can be controlled by removing water that contains a high level of impurities and replacing it with fresh water containing only the original levels of impurities. The process of removing water impurities from the system is called bleedoff or surface or bottom blowdown.