The swimming pool and SPA industry sector is increasingly booming, for the matching water treatment equipment products are also increasingly demanding, but for the basic product pump how to choose, due to the limitations of professional knowledge, many people are still "foggy", do not know what to do. Today, we will come together to explain some of the more common problems, I hope it can help you. For example: what are the basic requirements of a water pump, how to choose between fixed frequency and frequency conversion, what is the impact of the working noise of a water pump on the choice of water pump and so on. The following is an analysis of how to choose the right circulating water pump for swimming pools and SPA pools from these aspects.
First, the main performance parameters of the swimming pool circulation pump
The basic requirements of the water pump to start with the main performance parameters of the circulating water pump. Professional swimming pool and SPA pool circulating water pump and functional pump due to the design of self-infusion, can be ignored in the pump's allowable vacuum height and cavitation amount, its main performance parameters are: flow, head, shaft power and efficiency.
1. Flow Q [m3/h]: pump flow is the water output through the pump outlet in unit time, of course, it is in the pump resistance cycle filtering the whole system pressure, gain bit energy and kinetic energy measurement, so the flow is the flow under a certain head, different pressure head has different flow, high head when the flow is small, while the head hour flow is large.
2. Head H[m]: also known as the pressure head of a pump, the energy obtained per unit weight of liquid flowing through the pump. And the pressure head of the system in a specific swimming pool circulation filtration system is a certain range of change, the initial filtration, the system pressure head is small, the flow rate is large at this time; after running for a period of time, the filter interceptor gradually blocked the water flow channel, the pressure head becomes larger, the flow rate is correspondingly smaller. Inlet and outlet of the same pipe diameter of the pump, when the negative pressure vacuum table on the suction pipe and the pressure table on the outlet pipe are installed at the same level, the head of the pump is the sum of the suction range and pressure range. Factors affecting the size of the pump head: a. Pump structure (impeller size, bending degree); b. Speed; c. Flow rate.
3. Shaft power N[Kw]: the power transmitted by the motor to the pump shaft, that is, the power consumed by the pump shaft.
4. Efficiency n [%]: the effective power of the pump Ne (refers to the power of the mechanical energy obtained by the fluid) and the ratio of shaft power is called efficiency, n = Ne/No because the pump can not be completely motor input power without waste to the water flow, there is bound to be energy loss inside the pump, so the efficiency to measure the size of the energy loss and the degree of effective use of energy, the cause of energy loss: a. volume loss b. hydraulic losses; c. mechanical losses, etc.
Through the description of the above parameters can be seen swimming pool / SPA pool circulation pump selection is the most important to look at the flow and head to be able to achieve the design requirements of the water body, and then from the shaft power and efficiency of the two parameters to consider the requirements of energy consumption.
Second, the fixed frequency water pump and variable frequency water pump how to choose
1, The definition of the difference:
Fixed frequency water pump, refers to the frequency and speed is fixed, not in the case of no external force to change the motor rotation rate of the pump unit, such as domestic general with 50HZ power supply, motor rotation number more than 2850-2900r/min of two-pole motor, or rotation number 1450-1500r/min of four-pole motor.
Inverter water pump, mostly refers to the water pump with permanent magnet motor and integrated inverter and controller, can adjust the speed and time of the pump unit. That is, the frequency of the pump power supply can be adjusted to change the rotation speed of the pump motor.
2、Difference in application scenarios:
Fixed frequency water pump: applicable to various types of swimming pools, SPA water bodies. Because of the simple function of the unit, most of the electronic circuit control, can be better adapted to the complex room environment, fearless equipment room humidity, chlorine-containing environment and other characteristics. However, as the noise level of fixed frequency pumps generally reaches 70 dB and above (measured at 1 m from the motor), this can be equivalent to walking in a noisy urban area. If you are strict about the noise in the plant room, you need to choose a circulating water pump with a four-pole motor, which has a noise level of approximately 58 dB (measured 1 m from the motor) during normal operation, which is lower than the noise of a normal face-to-face conversation.
Frequency conversion water pump: because frequency conversion water pump is currently limited by technology and cost, civilian products are mostly small equipment, operating power is mostly within 2.2KW, sometimes used in small swimming pools, in fact, frequency conversion water pump applied in the pool not only does not save energy but also increase energy consumption, relatively speaking, frequency conversion water pump is still more suitable for application in the field of constant pressure water supply. Frequency conversion water pump normal working noise is about 53 decibels, the noise is low, the human activity rest will not have too much influence, but frequency conversion water pump can be adjusted high and low, the sound is not necessarily smaller than the fixed frequency water pump, high frequency greater than 50 when the sound will be larger than the sound of fixed frequency water pump. Therefore, it is more often used in environments where there is no civil engineering room reserved and the equipment needs to be installed in the living area.
Pressure-keeping water supply: The working principle of frequency conversion pumps is to automatically adjust the number of running pumps and the speed of one pump according to changes in the user's water consumption, so that the pump outlet pressure remains constant. When the user's water consumption is less than the water output of one pump, the control system adjusts the operation of one pump with frequency according to the change of water consumption; when the water consumption increases, the pressure in the pipeline system decreases, then the pressure sensor transmits the detected signal to the microcomputer control unit, and through the microcomputer's operation judgement, it issues a command to the frequency converter to control the pump motor and speed up the rotation speed to ensure that the system pressure is constant; conversely, when the water consumption decreases, the pump rotation speed is slowed down to ensure that the system pressure is constant. When the water consumption decreases, the pump speed will be slowed down to maintain constant pressure. When the water consumption is greater than the water output of one pump, the first pump will switch to frequency operation, and the second pump will start frequency adjustment operation. When the water consumption is greater than the water output of two pumps, one or two pumps will be stopped automatically. During the whole operation process, the constant pressure of the system is always maintained, so that the pumps always work in the high-efficiency zone, which not only ensures constant pressure water supply for users, but also saves electricity. Therefore, inverter pumps are mostly used in the field of constant pressure water supply.
3、The difference of economy:
Fixed-frequency water pump: because the power is constant, so the savings in electrical energy mainly help in the high adaptability of the flow head. In the previous engineering design, the head of the circulating water pump is chosen to be high, the actual working point of the pump is far away from the high efficiency zone, and it works in the low efficiency zone all year round, so there is a great waste of power consumption. Therefore, you can choose a four-pole motor circulating water pump, by changing the impeller diameter can reduce the head, improve the water flow, so that the head of the pump and the actual operation of a better match at the same time the flow rate can be greatly improved, such as half standard pool of circulating water pump power selection can be reduced by 30%, to achieve energy saving effect of about 30%. At the same time, the fixed-frequency water pump because of its simple function, the cost is relatively low, and the cost of after-sales maintenance is also lower.
Frequency conversion water pump: frequency conversion water pump in the swimming pool does not need strong filtration, can reduce the cycle, reduce the flow of water circulation, when the pump can run at low frequency and low power, to achieve the purpose of energy saving. However, the pool cycle is not recommended to use variable frequency pumps because adjusting the frequency down will easily reduce the water flow, causing alarm and damage to the relevant supporting equipment. For example: gas furnace heaters are not recommended for pools with variable frequency pumps. Because energy is conserved, inverter pumps will save energy while sacrificing water quality to a certain extent. At the same time, the frequency conversion pump has the power supply frequency regulation, time control and other functions, in the installation environment is more strict, requiring dustproof waterproof moisture, after-sales costs will also be higher, if encountered in the case of water soaking room can only be replaced.
The Technical Regulations for Swimming Pool Water Supply and Drainage Engineering stipulate that the circulation flow and the selection of equipment for the whole system are oriented towards fixed frequency pumps. Therefore, the swimming pool industry is dominated by fixed-frequency pumps worldwide, and variable-frequency pumps are generally used in the field of pressure-insulated water supply.