Water Properties Review PDF

**Water** is a tasteless, odorless substance that is essential to all known forms of life and is known as the universal solvent. It covers nearly 70% of Earth\'s surface. The water on earth is 97 % ocean (saline) and the fresh water, amounts only 2.7%. The fraction of water available for human use i...

**Water** is a tasteless, odorless substance that is essential to all known forms of life and is known as the universal solvent. It covers nearly 70% of Earth\'s surface. The water on earth is 97 % ocean (saline) and the fresh water, amounts only 2.7%. The fraction of water available for human use is only 0.03% of the total global supply. Water is called the \"universal solvent\". Pure water is neutral and has a pH of 7. **Surface tension** is the property of the surface of a liquid that allows it to resist an external force, due to the cohesive nature of its molecules. Examples of surface tension - Walking on water - Floating a needle - Washing with cold water - Why bubbles are round - Surface tension and droplets **Adhesion** is the ability of Water to attract to other substances. Water molecules are adhesive in that they stick to other surfaces. **Cohesion** Water is attracted to water. The water molecule is highly cohesive, it is very sticky, meaning water molecules stick to each other. **Capillary Action** Plants and trees couldn\'t thrive without capillary action. It helps bring water up into the roots. **Excellent Solvent** Water is an excellent solvent. Water has the unique ability to dissolve many polar and ionic substances. **High Heat Capacity** Water has high heat capacity. It takes a lot of energy to raise the temperature of a certain amount of water by a degree, so water helps with regulating temperature in the environment. **Heat of Vaporization** Water has high heat of vaporization. Humans (and other animals that sweat) use water's high heat of vaporization to cool off. Water is converted from its liquid form to steam when the heat of vaporization is reached. **Boiling Point** The boiling point is defined as the temperature at which the vapor pressure of the liquid is equal to the pressure surrounding the liquid, and thus the liquid changes to vapor. It is known to us that the boiling point of water is 100°C. **Freezing Point** The freezing point is the temperature at which the substance changes state from liquid to solid. So, for water, the point at which liquid state water turns to solid-state ice is the freezing point of water, which is 0°C or 32°F. **Density** is the ratio of the mass of the substance to its volume. An unusual characteristic of water is that, unlike most solids, ice is less dense than liquid water. For this reason, ice cubes float in a glass of water rather than sink to the bottom of the glass. The density of water is about 1 gm/cm3 and it varies with temperature in an unusual pattern. **pH** stands for power of Hydrogen Ion Concentration. It is really a measure of the relative amount of free hydrogen and hydroxyl ions in the water. The pH value of water is a measure of its acidity or alkalinity. **Turbidity** is caused principally by inorganic matter in suspension including mineral sediments and oxides of iron or manganese but organic matter including algae can also cause significant turbidity. The standard unit of turbidity is the nephelometric turbidity unit or **NTU** **Dissolved Oxygen** The oxygen that makes aquatic life possible does not form bubbles, nor is it the oxygen that is part of the H2O water molecule. Natural Factors Influencing Dissolved Oxygen o **Aquatic life**- Animals living in water use up dissolved oxygen. Bacteria take up oxygen as they decompose materials. Dissolved oxygen levels drop in a water body that contains a lot of dead, decomposing material. o **Elevation**- Since streams get much of their oxygen from the atmosphere, streams at higher elevations will generally have less oxygen. o **Salinity** (saltiness)- Salty water holds less oxygen than fresh water. o **Temperature**- Cold water holds more dissolved oxygen than warm water. o **Turbulence**- More turbulence creates more opportunities for oxygen to enter streams. o **Aquatic Vegetation**- Aquatic vegetation and algae directly release oxygen into the water during photosynthesis (during the day). At night, plants actually use oxygen for their metabolism. o **Riparian Vegetation** (plants along the stream)- Riparian vegetation shade the stream, decreasing water temperatures, and as temperature decreases dissolved oxygen increases. **Hardness of Water** Alkalinity and water hardness are fairly similar\--essentially, they both come from sources in nature. Water moves through rocks (and picks up minerals as it does so) on its way to rivers and lakes. **Soft Water** produces lather with soap solution easily is called soft water. It is a type of water that contains few or no calcium or magnesium ions. **Hard water** which does not produce lather with soap solution easily is called hard water. Hard water is water that has a high mineral content, such as metal ions, mainly calcium (Ca+2) and magnesium (Mg+2). **Temporary or Alkaline Hardness** Alkaline hardness sometimes referred to as temporary hardness, is due to the bicarbonates of calcium and magnesium dissolves in it. **Permanent or Non-Alkaline Hardness** Non alkaline hardness sometimes referred to as permanent hardness, it is due mainly to sulphates and chlorides of calcium and magnesium, which are acid in nature. **Fresh Wate** is found naturally on the Earth\'s surface as ice, as water in wetlands, ponds, lakes, rivers and streams, and as groundwater in aquifers. It usually has a low concentration of dissolved salts and solids **\*\*\*\*\*Types of fresh water\*\*\*\*** **Potable water** or drinking water is water fit for human consumption, which has undergone appropriate treatment and can be consumed without any risks. **Tap water** is also classified as fresh water. It is the water that comes out of the faucets in your house. **Hard water** contains calcium and magnesium. Though the incident of heart disease is lower in regions with hard water. **Soft water** can be naturally occurring, but it is usually soft due to an artificial process that removes the calcium and magnesium. **Salt water** It is also called seawater, found in the Earth\'s oceans and seas. It has a concentration of dissolved salts of about 3.5%. **Distilled water** Distilled water is a type of water wherein all its impurities as well as electrolytes were removed through distillation (that is, boiling the water and re-condensing the steam into a clean container, thus leaving contaminants behind). **Mineral water** is bottled directly from a natural spring, without being pumped or forced. **Demineralized water** Demineralized water is without heavy metals as well as nitrates, calcium, and magnesium due to a process in which the electrons of the water are neutralized. **Filtered water** Filtration in water may occur naturally or by an artificial process. The objective is to remove impurities. **Rainwater** The heat of the sun naturally distills rainwater. But it becomes contaminated as it falls through air filled with bacteria, dust, smoke, chemicals, and minerals. **Brackish Water** that has a higher salinity than fresh water but lower than seawater. **Freshwater** is water that contains less than 1% salt and thus has little to no taste, odor, or color. **Salt Water** is defined as the water present in the oceans and seas with a greater percentage of salt, minerals in them. Water that is composed of at least 3% salt and minerals. **Water chemistry analyses** are carried out to identify and quantify the chemical components and properties of water samples. **Pure water** is a clear, colorless liquid made up of oxygen and hydrogen. It is the most common substance on the earth's surface. **Cooling system** One of the most critical systems on ships. Large vessels need a way to safely remove unusable heat from their main engine, auxiliary engines, generators, and other machinery. **Cooling water** is used in industrial processes to dissipate large amounts of heat. The water has to meet specific requirements which is why it is analyzed on a regular basis. **Sea Water cooling system**: Seawater is directly used in the machinery systems as a cooling media for heat exchangers. **Freshwater or central cooling system**: Freshwater is used in a closed circuit to cool down the engine room machinery. The freshwater returning from the heat exchanger after cooling the machinery is further cooled by seawater in a sea-water cooler. **Freshwater** is used to cool machinery directly, whereas seawater is used to cool freshwater passing through a heat exchanger. **Seawater** [cannot be used for cooling the engine] because it is highly corrosive, and the replacement of these parts can be very costly. **Low-temperature circuit** is used for low-temperature zone machinery and this circuit is directly connected to the main seawater central cooler; hence its temperature is lower than that of high temperature. The L.T circuit comprises all auxiliary systems. **High-temperature circuit** in the central cooling system mainly comprises of the jacket water system of the main engine where the temperature is quite high. The **H.T water** temperature is maintained by low-temperature fresh water and the system normally comprises of the jacket water system of the main engine. The cooling water of the engine **should be only demineralized** (distilled) water with proper treatment, which is necessary for keeping effective cooling and preventing corrosion of the system. **Rainwater** is heavily contaminated and highly corrosive in general, which is also not recommended as cooling water. **Tap water** (drinking water) is not recommended as cooling water due to risk of chalk deposit formation inside the cooling system. **Corrosion** is partial or complete wearing away, dissolving, or softening of any substance by chemical or electrochemical reaction with its environment. **Corrosion** is partial or complete wearing away, dissolving, or softening of any substance by chemical or electrochemical reaction with its environment. Can also be produced because of the interaction of an alkaline corrosion inhibitor and the calcium and magnesium salts present in water. \*\*\*\*\* How Scale Form\*\*\*\*\* **Water hardness** -- the harder the water being used in an engine coolant, the greater the amount of scale formation. **Temperature** -- as coolant temperatures increase, hardness salts (calcium and magnesium) in solution become less soluble and increase their propensity to plate out on hot metal cooling system surfaces. **Temperature** -- as coolant temperatures increase, hardness salts (calcium and magnesium) in solution become less soluble and increase their propensity to plate out on hot metal cooling system surfaces **Entrapped air** -- any air bubble formation in a coolant area (bubbling around a hot source) increases the tendency for scale to form in that area. **pH** -- increases in pH will increase the potential for scale deposits. Damage to water pump seals. \*\*\*\*\*Engine Coolants\*\*\*\*\* **Marine Antifreeze** Coolant (or antifreeze) protects your engine from freezing while defending components against corrosion. It plays a critical role in sustaining engine heat balance by removing heat.**Coolant corrosion inhibitors** help decrease the corrosion rate of metals within your equipment and help maintain other coolant properties. **Corrosion inhibitors** are designed to minimize metal loss, which can reduce the useful life of heat exchangers, recirculating water piping, and process cooling equipment. **Water tube Boiler** A type of boiler where water flows through tubes that are surrounded by hot combustion gases in a shell. It is constructed with small tubes, where the water is contained inside the tubes **Fire-tube boiler** A type of boiler where hot flow gases flow inside the tubes that are submerged in water within a shell. It is consisting of a large tube where the product of combustion passes through the inside of the tubes, and outside the tube is surrounded by water. \*\*\*\*\*Properties of a fire tube boiler\*\*\*\*\* - Has Pressure up to about 10 bar - Can produce up to 14 tons of steam/hr. - Can meet wide and sudden load fluctuations because of large water volumes - Usually rated in HP (HORSEPOWER) \*\*\*\*\***Three Common Problems of Boiler Water**\*\*\*\*\* **a. corrosion** **b. carryover** **c. scale** **Corrosion** is partial or complete wearing away, dissolving, or softening of any substance by chemical or electrochemical reaction with its environment. It is the deterioration of a metal or alloy or its properties due to the reaction with its environment. Lubricating **oils** may contaminate the feed system and find their way into the boiler, this could be caused due to over lubrication of machinery and inefficient filtering of the feed. **Caustic Embrittlement** The phenomena of caustic embrittlement (or inter crystalline fracture) are believed to be caused by high concentrations of caustic soda (NaOH) and the material under stress. **pH** When the boiler water pH drops below about 8.5, a corrosion called [acid attack] can occur. The effect exhibits rough pitted surfaces. **Salts** Feed water employed for boilers is usually, unevaporated fresh, evaporated fresh or evaporated salt water. Evaporated fresh water is principally employed, along with evaporated salt water for water tube boilers. **Dissolved Gases Water** contains varying amounts of dissolved gases. It can contain up to 9 ppm oxygen at room temperature and atmospheric pressure. As the temperature increase, the solubility of oxygen decreases, but water under pressure can hold higher amounts of dissolved oxygen. Gases such as **oxygen and carbon dioxide** that are dissolved in distilled or fresh water will further contribute to the deterioration of the boiler system. If the water contains **carbon dioxide, carbonic acid** may be formed, which can cause corrosion. **Suspended solid** such as muds, sand, and clay settle to form deposits, promoting different Corrosion cells. **Temperature** High temperature increases corrosion. Usually, a temperature or pressure increase directly leads to a higher corrosion rate because electrochemical reactions generally occur faster at higher temperatures. Temperature increases add energy to the reactions, which increases the corrosion rate. **High temperature corrosion** -- this formed of attack can occur when loss of circulation causes the metal to overheat in a steam atmosphere. **General Wastage** is the overall reduction of metal thickness and is common in heating surface areas, such as boiler tube walls. This "thinning" of boiler tubes is often found in boilers having open feed systems (mostly auxiliary boilers) without any protective treatment. **Pitting Corrosion** is the most serious form of waterside corrosion and is the result of the formation of irregular pits in the metal surface as shown in the figure below. **Galvanic corrosion**, also known as bimetallic corrosion, is an electrochemical process whereby one metal corrodes in preference to another metal that it is in contact with through an electrolyte. Occurs when two dissimilar metals are immersed in a conductive solution and are electrically connected. An **anode** is an electrode through which the conventional current enters a polarized electrical device. This contrasts with a cathode, an electrode through which conventional current leaves an electrical device. **Sacrificial anodes** are sometimes used deliberately to give cathodic protection to more expensive material. **Sacrificial Anodes** are highly active metals that are used to prevent a less active material surface from corroding. Sacrificial Anodes are created from a metal alloy with a more negative electrochemical potential than the other metal it will be used to protect. **Hydrogen Attack.** It can penetrate the grain boundary of tube metal and react with carbon and produces methane gas. This carbon loss weakens the tube metal and methane gas exerts a pressure which separates the grains of tube. **Grooving**, whenever any section of the boiler is subjected to a localized stressing action, such as when holes are drilled in boiler plate or riveting, the metal in the immediate vicinity develops very tiny cracks, which are not visible to the naked eye but can be seen with a microscope. **Caustic Cracking** This is a form of intracrystalline cracking caused by water with a high level of caustic alkalinity coming into contact with steel has not been stress relieved. **Caustic Cracking** This is a form of intracrystalline cracking caused by water with a high level of caustic alkalinity coming into contact with steel has not been stress relieved. **Scale** It is a hard adherent coating that collects on the waterside of any heating surface. Scale formation or deposits in the boilers results from hardness contamination of feed water. It is a hard adherent coating that collects on the waterside of any heating surface. Scale formation or deposits in the boilers results from hardness contamination of feed water.