Domestic water supply system is mainly used for pressurized water pumps, general requirements according to specifications 2 to 4 pumps in parallel and alternately should automatically switch to run. The more the water pump station, the area to large, investment is high, more than the point of failure. However, to water safety, life, water supply system pumps tend to consider the alternative, and there are two ways: First, equipment, pumps, pump units that work in determining the number of cases, a certain number of separate standby pump, standby pump and work Pumps to install, and it can be put put the standby pump, pump problems arise when the work standby pump to be replaced in time; second standby for each other, only consider the work of the pump, the pump according to the design flow to determine the number of (less than 2 units) , The runtime automatically increase or decrease according to the actual water pump station number changes, idle standby pump, designed to achieve full capacity only when all the pump run, and run the risk of the whole pump is small, the time is short. 
 

Standby pump about life in China, "Architecture design of water supply and drainage"(hereinafter referred to as "norms ") is also clear that, as early as GBJ 15-88 "Standards " section 2.7.2 provides that "living water supply system should be established for a water pump Spare unit ", the current GB 50015-2003 " norms "(2009 edition) Section 3.8.1 provides that " living water pump pressurized water system, should the pump equipment. "Thus, "norms"from the GBJ 15-88 to GB 50015-2003, the requirements of life increasingly stringent standby pump, mainly because:

 

    1) The water supply system of the importance of life in raising awareness;

    2) The country can not guarantee a good quality of products and pump repair time rate of the pump in case of a problem concerned not timely repair or replacement will affect the domestic water supply;

    3) water pump life safety requirements in the continuous improvement;

    4) design security considerations;

    5) With reference to a large number of engineering practice at home and abroad.

 

In fact, the life of the pump flow and the number of units is determined by the design flow, design flow is in the most adverse design conditions in accordance with the "standard" computing the maximum limit of flow, that is, the number of water, water quotas, sanitary ware, water time , Hours, coefficient of variation all reached the ideal flow design conditions, but the actual operation is difficult to achieve the most unfavorable conditions, there will always exceed the actual needs of the design flow; but also with building the actual nature of water, residents occupancy rate , Habits, water systems, climate, water and other factors, as well as non-uniform changes in water 24 hours, most of the time, the small flow of water, while the maximum flow is not much there, but occasionally 1 or a few times Not even appear. Thus, engineering design prevalent in water pump design flow is much larger than the actual phenomenon. General, when used in the design of the work of 2 to 3 sets of pumps, actually, only one pump running and the pump frequency mostly in the 25 ~ 40Hz, even when the water peak is also 45Hz below, a similar phenomenon is so widespread throughout the country, which Of course, the design flow with the water of life itself larger than the actual water use is related to the design of more specifically did not rule out the surplus to increase the amount of design possibilities. 
 

It seems that pumps life alternate with each other yet is an excellent program. For example, according to the design flow using 3 sets working pump, but the actual water is uneven, large or small changes, in general, only one water pump when running idle the rest of the pump, in fact, become the standby pump, only in the water peak Achieve the maximum possible water only 2 to 3 pumps running, and running at the same time not very long, generally not a day more than 2 hours. In other words, life can pump frequency control is the standby for each other, especially in the large water change (coefficient of variation of more than 1.5 hours) in the case. When the pump is directly connected in series without negative pressure water supply, due to the use of water pipe network pressure leaving the pump Q ~ H shifted the whole curve, which may cause the actual supply capacity of a single pump design flow rate greater than the single pump, the pump is more conducive to Mutual backup. 
 

Therefore, mutual backup pump life than normal idle standby pump is more reasonable, because the pump design flow itself is greater than the actual amount of water, then add a spare pump to form an alternate name of two or more pumps, will increase investment and Area; and clearance in the pump case quality, very small chance of a bad water pump, water pump is broken even if the water supply will not be early detection, early notification and timely maintenance, in the middle no more than 24 hours, which for most users Terms is understandable and acceptable, not to mention frequent failures. Frequent failure of the pump must not be used in the project. Of course, if the choice of a 24-hour working pump station operation, the pump should be the other equipment; to allow continuous flow of water or use a constant water supply situation, such as full flow of water, taking into account such as water and fire-star hotels, hospitals and other important buildings Water supply system of living things, but also wish to consider setting standby pump. 
 

Therefore, the Water Pump is set to standby pump, need to water the importance of the work on water safety requirements and the number of pump sets, water pump repair frequency and degree of difficulty, etc., through technical, economic and security compared finalized. As for the "standard" requirement, the proposed focus on practical examples and detailed analysis through the project, not a comprehensive water supply system in accordance with life "should Equipment Pump" requirement. When a user (or water company) strongly urge the pump equipment can be considered an appropriate choice of pump design flow rate smaller, so that both meet the design requirements, but also meets the wishes of investors. 
 

『Note: This article is from the " Water World "magazine in 2010, 6 (bimonthly, with a total 90 s period) published " Analysis of the pumps life alternate water supply system, "the article excerpt and modify』