Expansion Tank Constant Pressure Water Supplying Device

 
Inverter applications in the area of Water Supply System
I. Overview 

     Water Supply refers to changes in the water supply network, the outlet pressure remains constant water supply. Water supply
network system outlet pressure value is determined based on user needs. The traditional way is to use constant pressure water towers, water tanks, pressure tanks and other facilities to achieve. With increasingly sophisticated and extensive application of frequency control technology, the use of the combination of the inverter, PID controller, microcontroller, PLC and other devices, constitute a control system, adjust the pump output flow, constant pressure water supply. The technology to spread in the water industry. Constant pressure water supply system main features:

 1, energy saving can be achieved by 20% -40%, to achieve green electricity. 

  2, small footprint, less investment, high efficiency. 

  3, flexible configuration, high degree of automation, functional, flexible and reliable. 

  4, run reasonable, because it is soft starting and soft stopping, not only can eliminate water hammer effect, and the average
 
torque of the motor shaft and wear reduction, reducing the amount of maintenance and repair costs, and greatly improve the life of
 
the pump. 

    5, due to the constant pressure water supply directly from the governor to reduce the secondary pollution of existing water
supply, to prevent the infection source of many infectious diseases. 

   6, through the communication control, unattended, saving manpower and resources.


 Second, the shortcomings of the traditional way of constant pressure 

1, the management of inconvenience, because communication with the air duct can lead to corrosion; 

2, due to the tank microbes, algae breeding, the system may also cause secondary pollution, so the constant pressure tanks are subject to regular annual maintenance inspection by the health and quarantine departments; 
3, constant pressure tank takes up more space, you need to place a special place; 

 4, the high constant pressure control system by the tank into the pump to adjust the number of units, but this can not be the best way to adjust to match water supply and water consumption, water pumps and efficient long-term deviation from the work area, and inefficient; 

 5, the system frequently start and stop the pump, for pumps, motors and switching devices will shorten the service life; 

  6, the use of high water tank of water, the flow in the system is large, there will be greater pressure pipe network changes, causing some users to use pressure head is not enough funding, such as the lack of flow occurs, Enthusiasm, etc.; 

  7, for the pump in the selection, design staff in order to improve the safety factor systems, motor selection are larger; in small or low-load area with water using the valve, orifice plates, etc. to adjust the residual head when a large number of the energy consumption of the valve, resulting in energy are wasted.



 
 
 

   Third, the main applications of frequency control water supply equipment 

  1, high-rise buildings, urban and rural communities, enterprises and domestic water. 
 2, various industrial needs constant control of water, cooling water, heating network water cycle, water boilers, etc.. 
  3, the central air conditioning system. 

  4, pressurized water plant systems. 

   5, irrigation, sewage treatment, artificial fountains. 

   6, various fluids constant pressure control system. 

    Fourth, the water supply technology 

     By installing a pressure sensor in the pipe-line, the pressure is converted into 4 ~ 20mA analog signal through the built-in PID controller inverter to change the electric pump speed. When water users increases, the pressure in the pipe below the set pressure, the inverter output frequency increases, the pump speed is increased, increasing the amount of water, when it reaches the set pressure, the electric pump speed is not changed, constant pressure in the pipe on the set pressure; vice versa.
 
 
 

model	Overall Volume  (m3)	Adjusted volume (m3	Inlet and outlet (mm)	Height of device(H)	Diameter of tank Φ1	Length of trestle A	Width of trestle B	Weight of tank (Kg)
YL-400	0.125	0.038	25	1200	400	1200	700	150
YL-600	0.4	0.15	50	2000	600	1500	800	250.1
YL-800	0.90	0.35	50	2500	800	1800	900	325.7
YL-1000	1.37	0.41	65	2680	1000	2000	1100	430.4
YL-1200	2.30	0.59	65	2970	1200	2200	1300	815
YL-1400	3.40	1.02	80	3350	1400	2400	1400	1150
YL-1600	5.034	1.57	80	3600	1600	2600	1600	1367
YL-1800	7.06	2.12	100	3600	1800	2800	1900	1863
YL-2000	9.42	2.85	100	3800	2000	3000	2100	2281

 


For solving the problem of poor quality and waste of electric energy coursed by water supply mode of a high water tower and a direct water pump, introduce a constant pressure supply water system, which adopts embedded fuzzy control technology, using PLC and frequency convener as its core. When the system runs, water pressure of the pipe is inputted into the PLC from terminal X0 through pressure transmitter. Comparing the value of measured pressure with its set value, PLC controls the work frequency of the frequency converter by the output signal on fuzzy calculation in order to control rotation speed of water pump and adjust water pressure of the pipe. The real time control performance to the water pressure of water supply system designed in this paper was proved to be all-right according to the experimentation validated. The hard ware module is steady-going and reliable, and the fuzzy controller is proper and valid and can guarantee the better stability of water pressure.
 
 

How Constant Water Pressure Systems Work?
 
Let's say that the system installed is a C.P 75 Sub- Drive 1-1/2 hp (20 gpm ) with a set pressure of 65 psi, as you open up the kitchen faucet which takes approximately 3 gpm the pressure transducer reads the pressure drop and sends the signal to the drive which then ramps up the pump to maybe 1800 rpms, because the demand is only 3 gpm the pump doesn't need to spin any faster to maintain the 65 psi set pressure, as you open up additional faucets creating more of a demand the rpms of the motor speed up to meet the demand and maintain the 65 psi set pressure. As the demand subsides the rpms slow down until the pump go's into sleep mode when no water is being used.
The advantages are the electric that runs the pump is more economical in that it's a 3 phase motor, no pressure fluctuations when water is being used at different locations in the house, the entire system is wall mounted with a small pressure tank which free's up floor space. Constant water pressure systems come in a variety of models ranging from 20 gpm through 90 gpm.