Atmospheric Pressure: Atmospheric pressure is the pressure of the air around us. An atmosphere (atm) is a unit of measurement equal to the average air pressure at sea level at a temperature of 15 degrees Celsius (59 degrees Fahrenheit). One atmosphere is 1,013 millibars, 760 millimeters, 29.92 inches of mercury, or 14.696 PSI.
Booster Pump: An additional pump and prime mover assembly used to increase the velocity of the material in the pipeline to enhance pumping power and pumping distance.
Concentration By Volume (Cv): is the volume of solids in a liquid divided by the total volume of the solution.
Concentration by Weight (Cw): The concentration by weight reflects the percent ratio of the mass of dissolved solids to the total mass of the solution.
Cutter Hydraulic Pump Temperature: This temperature is the hydraulic pump case temperature. The temperature should not exceed 180° F for any extended time of operation.
Cutter Pressure : This is the hydraulic pressure for the cutter system. It varies as the material dredged varies and the speed of the swing. Get a base line cutter pressure with the cutter operating at full speed in water not touching any material. The base line pressure can aid the operator in determining if the cutter is clear or operating with trash caught in it. Know the stall pressure for the cutter. This is the pressure that the cutter stops, approximately 4600 psi.
Density: The amount of a substance contained within a specific area. In physics, density is the ratio of the mass of a substance to its volume, and it can be calculated by dividing the mass by the volume. Density is often expressed in units such as grams per cubic centimeter (g/cm3) or pounds per cubic foot (lb/ft3) on the dredge it is the specific gravity of the slurry. Specific gravity is the density of a substance divided by the density of water at 4°C (39°F) Gold has a density of 19.3 g/cm3, so its specific gravity is 19.3 g/cm3 divided by 1 g/cm3 (the density of water at 4°C), or 19.3. This means that if the displayed slurry density is 1.5 the slurry is 33 percent heaver then water at 4°C or 20 percent by weight. ((1.5-10) / (1.5)) 100 = 33%
Discharge Head: Resistance to the slurry flow in the discharge system calculated in feet of water. The discharge head consists of the discharge friction head, discharge velocity head and discharge static lift.
Discharge Pressure: The discharge pressure is displayed in pounds per square inch (PSI). It is a display of the pressure in the discharge line. The pressure changes as the discharge head changes.
Dredge Advance: To describe the dredge movement from one set of anchor positions to another.
Dredge Pump: The device that moves the slurry in the pipeline. Slurry enters the casing and is whirled by turning impellers, which force it out of the casing and into the pipeline.
Dredging: An excavation activity in which materials are recovered from beneath the water's surface. The purpose is generally to gather bottom sediment and either dispose of it at a different location or use these sediments in various products; e.g., sand and gravel that is used in concrete mixtures.
Dredging Depth: Dredging depth is the vertical distance below the surface of the water to the deposit to be dredged.
Elevation: The angle at which a pipeline rises as it leads away from a dredge pump. Pipeline elevation can increase material’s friction and decrease its velocity, reducing efficiency. Elevation is typically the measurement from the surface of the water to the final discharge point.
Gear Temperature: This is an indication of trouble if one of the bearings or oil gets too hot. On premium EP oil, the peak operating temperature should be 160° F. If the temperature exceeds 160° F, the life of EP oil will be reduced. High temperature may be an indication that the level of the oil is too high or that the unit has the wrong oil in it. It can also be an indication of possible bearing failure.
Head: Head is another increment to measure pressure, like how distance can be measured in miles or kilometers. Head is the pressure created by the weight of 1 foot of fresh water measured at sea level at 60° F
Hydraulic Dredging: The process of excavating and pumping underwater material through a pipeline to a different location using a centrifugal pump.
Hydraulic Oil Temperature: This is the displayed temperature of the hydraulic oil. The maximum hydraulic oil temperature should be between 160° F and 180° F. The minimum oil temperature before fully loading the hydraulic system is 70° F. Use the heating system to bring the oil up to the minimum operating temperature.
Hydraulic Pump Charge Pressure: The hydraulic charge pump is necessary to supply cool fluid to the system, to maintain positive pressure in the main system loop, to provide pressure to operate the control system and to make up for internal leakage. The normal operating pressure is between 350 psi and 380 psi, the pump control will not operate properly if the charge pressure falls below 180 psi.
Mechanical Dredging: The process of removing debris or hardened material that is tightly compacted, using buckets to dig and place the material in barges to transport it to different locations.
Priming A Dredge Pump: Evacuating the dredge pump of air and starting to pump the slurry or water.
Pump Speed: The speed at which the pump’s impellers force the water and material into the pipeline. Pump speed is increased to maintain proper slurry velocity as the dredge moves farther away from the discharge point.
Sediment: Materials that are naturally occurring and broken down by weathering and erosion.
Service Water Pressure : The service water is displayed in pounds per square inch (PSI). The service water should never be less than the dredge discharge pressure and ideally it is higher than it.
Slurry: A thin mixture of an insoluble substance, such as cement, clay, or coal, combined with a liquid, such as water or oil.
Static Lift/Terminal Elevation: Static lift is the vertical difference between the surface of the water and the point of discharge.
Suction Head (Displayed As Vacuum Or Differential Pressure) : Suction head is the resistance to the slurry flow in the suction system calculated in feet of water. The suction head consists of the entrance head, suction friction head, suction velocity head, and suction static lift. Vacuum is actually a display of differential pressure for underwater pumps. It may be displayed as inches of mercury or pounds per square inch. The dredge pump vacuum/differential display is one of the most important dredging displays on the operator's touch screen, for this display indicates conditions in the dredge suction pipe as they occur. A submerged dredge pump relies on atmospheric pressure and the weight of the water column above the pump to push water and material into its case; the dredge suction vacuum/differential gauge indicates the effectiveness of the use of this pressure. Three suction differential readings are of importance to the operator:
The clear water differential should be kept as low as possible and still allow adequate velocity for conveying material; the clear water differential can be regulated by the pump speed. The effective differential, unlike the clear water differential, is a measurement of the suction losses due to conveying material. It is therefore favorable to maintain as high an effective differential as possible without causing cavitation or pipeline plugging.