High-viscosity pumps are gear pumps designed to transport high-viscosity liquids. They should deliver the maximum flow rate with minimal power consumption, minimal leakage, and high pressure. When determining the medium to be transported, the specifications in the product manual should be strictly followed, using the manufacturer's recommended fluid medium whenever possible, and the system's operating temperature range should be carefully considered. When a wider temperature range is desired, the viscosity index of the transported medium should be higher. The transported medium is not only an energy transfer medium but also a lubricant, sealant, and heat transfer medium. Excessively high liquid viscosity increases internal friction resistance, reduces output power, wastes energy, and generates excessively high system temperatures. Safety valves or other protective devices should be installed on the outlet pipe of high-viscosity gear pumps. This allows for pressure relief in case of blockage in the pump's outlet passage. For high-viscosity gear pumps requiring forward and reverse rotation, safety valves must be installed on both the inlet and outlet pipes.
Selection of Working Pressure: The rated pressure of a high-viscosity pump refers to the maximum permissible pressure during continuous operation. Its working pressure is determined by the external load, and its installation and commissioning lifespan is directly related to its working pressure. For gear pumps that are not frequently used, the operating pressure can be taken as the pump's rated pressure. Considering the different product qualities, it is best to reduce the rated pressure by 20% to 30%. For gear pumps that frequently operate at higher pressures, the operating pressure should be 1 to 2 pressure levels lower than the pump's rated pressure. Petrochemical equipment often operates continuously for 24 hours. In this case, the pump's operating pressure should be much lower than the rated pressure, and the operating speed should also be lower than the rated speed. If the operating pressure of a high-viscosity gear pump is set too high, it will cause the gear pump to operate under overload.
Installation and Trial Operation: The support or flange of the high-viscosity pump and its drive motor should use the same mounting foundation. The foundation, flange, or support must have sufficient rigidity to reduce the vibration and noise generated during the operation of the gear pump. The motor and gear pump must be connected with a flexible coupling, with a coaxiality of less than 0.1 mm and an inclination angle not exceeding 1 degree. Do not use a hammer to strike the coupling during installation to avoid damaging the gears and other parts of the gear pump. If a pulley, sprocket, or other similar drive is used, a bracket should be provided for support to prevent radial force on the drive gear bearing. When tightening the foundation bolts of the gear pump and motor, the bolts should be evenly stressed and the connection reliable. When turning the coupling by hand, the gear pump should rotate easily without any jamming or other abnormalities before piping can be installed. The inner diameter of the suction pipe for high-viscosity gear pumps should be large enough, avoiding narrow passages or sharp bends, minimizing elbows, removing unnecessary valves and accessories, and lowering the pump's installation height as much as possible to shorten the suction pipe length and reduce pressure loss. Pipe joints and other components must be well-sealed to prevent air intrusion, thereby controlling cavitation and erosion. Before starting operation, fill the gear pump housing with the liquid to be pumped to facilitate safe startup. If the ambient temperature is below freezing, preheat the pump by introducing hot steam before starting. The rotation direction of the gear pump must match the inlet and outlet ports. If the gear pump is being used for the first time or after a long period of inactivity, it is best to run it under no-load or low-load conditions for about one hour. If abnormal temperature rises, leaks, vibrations, or noises are detected during the break-in period, an immediate inspection should be conducted.
High-viscosity pumps should also be equipped with safety valves or other protective devices on the outlet pipeline. This allows the safety valve to be opened to relieve pressure should the pump's outlet passage become blocked. For high-viscosity gear pumps that require forward and reverse rotation, safety valves must be installed on both the inlet and outlet pipelines.
