Pump knowledge: According to the principle of pump selection, the use of reasonable pump selection method can extend the service life of pump products, improve pump efficiency and reduce energy consumption. Finally, it achieves the goal of economy, efficiency and energy saving.
Principles of pump selection: economy, efficiency and energy saving
1. Economic Principle: According to the specific gravity, viscosity, corrosion and other characteristics of the medium, choose the most appropriate pump material and the most suitable pump type, so as to ensure the service life of the pump.
2. High efficiency principle: choose high efficiency pump as far as possible, choose large pump as far as possible when the performance parameters are also suitable, because large pump is more efficient than small pump.
3. Energy-saving principle: try to let the pump in equal to or close to the rated operating conditions, so as to improve the efficiency of the pump operation. In addition, full consideration should be given to the joint operation of the pump, as far as possible to make the pump in all cases to maintain high efficiency.
Method of pump selection (step):
First, list the basic data:
1, medium characteristics: media name, specific gravity, viscosity, corrosion, toxicity and so on.
2. The diameter and content of particles in the medium.
3. Medium temperature
4. The flow needed
5, pressure: suction tank pressure, drain pool pressure, pipe system pressure drop (head loss).
Two. Determine flow and lift:
1. Flow rate is one of the important performance data of pump selection, which is directly related to the production capacity and transportation capacity of the whole unit. For example, in the process design of the Design Institute, we can calculate the normal, minimum and maximum flow of three pumps. When choosing the pump, the maximum flow rate is taken as the basis, and the normal flow rate is taken into account. When there is no maximum flow rate, the normal flow rate of 1.1 times is usually taken as the maximum flow rate.
2. The head required by the device system is another important performance data for pump selection. Generally, the type of pump should be selected by enlarging the allowance of 5%-10%.
Three. Determine the material of the pump:
1. The material of the pump must meet the requirements of the medium characteristics: liquid properties, including the name of the liquid medium, physical properties, chemical properties and other properties. Physical properties include temperature C density d, viscosity u, solid particle diameter and gas content in the medium, which involves the head of the system, the calculation of effective cavitation allowance and the type of suitable pump; chemical properties, mainly referring to the Chemical Corrosiveness and toxicity of the liquid medium, are an important basis for selecting pump materials and selecting the type of shaft seal. According to it.
Four. Determine the type of pump:
1. According to the arrangement of the device, topographic conditions, water level conditions, operating conditions, determine the selection of horizontal, vertical and other types (pipeline, diving, under-water, non-plugging, self-priming, gear type) of the pump.
2. According to the nature of the liquid medium, the water pump, hot water pump or oil pump, chemical pump or anti-corrosion pump or impurity pump, or the use of non-clogging pump. The pump installed in the explosion area should adopt the corresponding explosion-proof motor according to the grade of the explosion zone.
3. According to the flow rate, determine whether to select single-stage pump or double-stage pump; according to the height of the lift, select single-stage pump or multi-stage pump, high-speed pump or low-speed pump (air conditioning pump), multi-stage pump efficiency is lower than single-stage pump, such as single-stage pump and multi-stage pump can be used, the first choice of single-stage pump.
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