After determining the flow and head of the multi-stage stainless steel feedwater pump, then you can use the technical chart and the description of the relevant pump parameters to select the pump.
1. Selection criteria for multi-stage stainless steel feed water pump
1) The selected multi-stage stainless steel feed water pump model meets the parameters of the pump device flow, head, pressure, temperature, cavitation flow, suction lift and other parameters;
2) The mechanical aspect of the water pump is highly authentic, low noise, and low vibration
3) In terms of cost, customers should consider pump equipment operating costs, post-maintenance fees and management fees.
2. Determination of flow rate of multi-stage stainless steel feed water pump
Flow rate is one of the important parameters for pump selection, which directly affects the production capacity and delivery capacity of the pump. The design institute generally calculates the normal, minimum, and maximum three flow rates of the pump. The pump selection is generally based on the maximum flow rate. The maximum flow of the water pump is generally 1.1 times the normal flow of the water pump as the maximum flow.
Pump flow selection, generally refer to the parameters on the pump product catalog to select the pump flow. For example, the flow can be 1.1 to 1.2 times the rated flow of the air source unit (1.1 for a single unit, 1.2 for two units in parallel) or calculate according to the following formula :
Q=1.163L*ΔT
—Q is the cooling capacity of the air source host
—L is the system cooling water flow
—ΔT is the system temperature difference
L(m3/h)= Q(kW)/(4.5-5)℃x1.163X(1.1-1.2)
3. Determination of the lift of the multi-stage stainless steel feed water pump
Pump head composition: Hmax=△P1+△P2, △P1 is the resistance along the pipeline, and △P2 is the local resistance of the pipeline.
1) Pressure loss along the system
The pressure along the way refers to the continuous and consistent pressure loss in the pump pipeline. Find out the most unfavorable loop in the pump pipeline, the furthest branch loop in the pipeline network system, and the largest resistance in the pipeline network system. .
△P1=The most unfavorable pipe length*specific friction
Generally, the loss along the way per 100 meters of tube length can be roughly estimated as 5mH2O
2) System local resistance
Partial pressure loss refers to the non-continuous pressure loss caused by special components in the pipeline system that change the direction of water flow or make local water flow channels narrow (such as reduced diameter, three-way, valve, joint, filter, etc.) , The local resistance is mainly composed of the following.
(1) The water resistance of the air source unit: generally 6-8mH2O; (for specific values, please refer to the product catalog)
(2) The water resistance of the surface cooler or evaporator of the terminal equipment (air handling unit, fan coil, etc.): generally 5-7mH2O; (for specific values, please refer to the product catalog)
(3) The resistance of the backwater filter is generally 3-5mH2O;
(4) Valve (check valve) water resistance: generally one is 3mH2O;
(5) The local resistance loss of the refrigeration system water pipe tee, joint, etc.: generally 3-4mH2O;
To sum up, according to the calculated total resistance and take a safety factor of 10%, the head of the boiler feed water pump is obtained
Before selecting the multi-stage stainless steel feed water pump, the delivery medium must be determined. If it is clean water, you can choose cast iron centrifugal water pump products. For sewage, you can choose pneumatic pumps or sewage pumps. If the delivery medium is corrosive, you need to choose stainless steel or Fluoroplastic material.
In the pump product sample selection parameter table, select the head value that is consistent with or close to the design head; then find the flow value that is consistent or close to the design flow in the vertical table, and cross it vertically and horizontally in a small square. The pump model is marked, and the pump model is initially selected. Sometimes there are two models that meet the design requirements. At this time, we need to make a comparison, analyze and compare economic benefits, and then select a suitable model for the customer For water pumps, if a single pump cannot meet its requirements when the pump design flow and head are relatively large, then you can consider choosing a multi-stage pump to meet its needs. Try to select a pump with a flow head similar to the customer’s needs, which is also conducive to the later operation of the pump. Maintenance and management.
