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According to different working conditions and medium properties, mechanical seals include high temperature and low temperature resistant types, high pressure resistant and corrosion resistant types, particle resistant types and ones suitable for light hydrocarbon medium that are easy to vaporize. Mechanical seals of different structural types and materials should be selected as per different usages.
The parameters that need to be considered in selection of mechanical seal are as follows:
1. The physical and chemical properties of conveyed medium, such as corrosiveness, solid particle content and size, density, viscosity, vaporization pressure, gas content in the medium, and whether the medium is easy to crystallize, etc.
2.Effective installing space (D and L), etc.
3. Process parameters
(1) Sealed chamber pressure P
Pressure in sealed chamber refers to fluid pressure in sealed chamber, and this parameter is main parameter used for sealing.When determining pressure in sealed chamber, in addition to getting knowledge of the pump inlet and outlet pressures, it is also necessary to know type and structure of the pump.
For newly purchased pumps, the most convenient and reliable method is to obtain pressure data of the sealed chamber from the pump manufacturer; for on-site equipment,the easiest way to confirm pressure of the sealed chamber is to install a pressure gauge on the sealed chamber.
In order to facilitate selection of mechanical seal, the following table gives sealed chamber pressure value Pm for reference.
(2) Fluid temperature T refers to the fluid temperature in the sealed chamber.
(3) Sealing peripheral speed V refers to peripheral speed of shaft of the mechanical seal,calculated by the following formula：
V=πnd/60，d is the shaft diameter, m; n is the pump shaft speed, r/min.
The parameters that need to be considered in selection of mechanical seal are as follows:
1. The physical and chemical properties of conveyed medium, such as corrosiveness, solid particle content and size, density, viscosity, vaporization pressure, gas content in the medium, and whether the medium is easy to crystallize, etc.
2.Effective installing space (D and L), etc.
3. Process parameters
(1) Sealed chamber pressure P
Pressure in sealed chamber refers to fluid pressure in sealed chamber, and this parameter is main parameter used for sealing.When determining pressure in sealed chamber, in addition to getting knowledge of the pump inlet and outlet pressures, it is also necessary to know type and structure of the pump.
For newly purchased pumps, the most convenient and reliable method is to obtain pressure data of the sealed chamber from the pump manufacturer; for on-site equipment,the easiest way to confirm pressure of the sealed chamber is to install a pressure gauge on the sealed chamber.
In order to facilitate selection of mechanical seal, the following table gives sealed chamber pressure value Pm for reference.
(2) Fluid temperature T refers to the fluid temperature in the sealed chamber.
(3) Sealing peripheral speed V refers to peripheral speed of shaft of the mechanical seal,calculated by the following formula：
V=πnd/60，d is the shaft diameter, m; n is the pump shaft speed, r/min.
