Non negative pressure water supply equipment is a development and extension of variable frequency constant pressure water supply equipment, which uses the municipal pipeline network as the water source, fully utilizes the existing pressure of the municipal pipeline network, and forms a closed continuous relay pressurized water supply method. It has good energy-saving effect and no secondary pollution of water quality.

catalogue
1 Introduction
2 components
3 Control Points
4 Scope of application
5 advantages and disadvantages
Seven major issues with traditional water supply methods
The non negative pressure water supply equipment we usually refer to is a non negative pressure variable frequency water supply equipment, also known as a variable frequency non negative pressure water supply equipment, which is a boosting device directly connected to the water supply network. The traditional water supply method cannot do without a reservoir. The water in the reservoir is usually supplied by a tap water pipe, so the pressurized water enters the reservoir and becomes zero, causing a large amount of energy to be wasted.


The non negative pressure water supply equipment is an ideal energy-saving water supply equipment. It is a secondary water supply equipment that can be directly connected to the tap water pipe network without any side effects on the tap water pipe network. Based on the pressure of the municipal pipe network, it can directly stack and supply water, saving energy. It also has many advantages such as fully enclosed, pollution-free, small land occupation, fast installation, reliable operation, and easy maintenance.

Non negative pressure water supply mainly consists of non negative pressure stabilizing tank, pressure tank (diaphragm or airbag expansion tank), non negative pressure control cabinet, water pump, motor, filter, backflow preventer, sensor, electric contact pressure gauge, pipeline components, base, etc.


There are various forms of non negative pressure equipment on the market:
1. Stable pressure compensation type non negative pressure water supply equipment

2. Box type non negative pressure water supply equipment

3. Stacked high-level storage and water supply equipment

4. Tap water booster pump station

The non negative pressure water supply equipment achieves non negative pressure on the municipal pipeline network through intelligent control technology and voltage stabilization compensation technology, ensuring uninterrupted water supply to the user pipeline network. The flow controller used in the equipment can automatically adjust the input water volume from the municipal pipeline network to the equipment while maintaining low service pressure, ensuring that the municipal pipeline network does not generate negative pressure. During peak water use periods, the energy storage device releases a certain pressure of nitrogen gas pre filled to ensure that the water in the high-pressure chamber of the pressure stabilization compensation tank is compensated to the constant pressure chamber with a certain pressure, which can supplement the insufficient water supply from the municipal pipeline network within a certain period of time. Through a bidirectional compensator, the pressure stabilization compensation tank is stored during low water use periods to provide pressure stabilization compensation for the user's pipeline. At night and during low flow water supply, water can be supplied through a small expansion tank to prevent frequent pump start-up. Fully utilizing the pressure of the municipal pipeline network, the energy-saving effect is significant. If the water pump is directly connected to the municipal pipeline network, there is no need to build a reservoir, it can be directly connected to the municipal pipeline network. However, according to the urban water supply regulations in China, in order to prevent any impact on the water use of surrounding residents, it is not allowed to install domestic or production water pumps directly on the municipal pipeline network. In order to solve the problem of water supply equipment being able to be connected in series with the municipal water supply network without generating negative pressure, and without affecting the water use of other users, it is necessary to install a non negative pressure flow controller, a segmented pressure stabilizing compensation tank, a bidirectional compensator, etc. between the pump inlet and the municipal water supply network. The non negative pressure flow controller constantly monitors the pressure of the municipal water supply network, ensuring that the municipal water supply network does not generate negative pressure while also fully utilizing the existing pressure of the municipal water supply network.

1. Non negative pressure flow controller
The non negative pressure controller constantly monitors and controls the pressure in the municipal pipeline network and compensation tank. When the tap water pressure is insufficient, the non negative pressure controller starts working to ensure that the water pressure in the municipal pipeline network is not affected. This not only ensures the safety and stability of water use for users, but also ensures the stability of the pressure in the municipal pipeline network.

2. Bidirectional compensation device
The bidirectional compensation of the energy storage and release regulating device can automatically compensate for the continuous water volume of the tap water pipeline network, and also play a role in stabilizing the pressure compensation of the user pipeline network, ensuring that the equipment does not generate negative pressure on the tap water pipeline network. During the low peak period of water supply, the bidirectional compensator starts to work, directing the high-pressure water at the outlet of the water pump to the high-pressure chamber to continue replenishing water. As the liquid level gradually rises, the pressurized nitrogen gas is squeezed back into the energy storage device, completing the process of replenishing water in the tank during the low peak period. When the water supply or municipal pipeline pressure drops during the peak period, the energy storage device releases energy, squeezes the high-pressure chamber water to supplement the constant pressure chamber, and together with the municipal water in the constant pressure chamber, replenishes water to the user. This completes the process of replenishing water to the user during the peak period.

3. Energy storage device
The energy storage device is equipped with pre pressurized nitrogen gas that is insoluble in water. During peak water supply periods, it releases energy to squeeze high-pressure chamber water and replenish it to the constant pressure chamber pipe network. By fully utilizing the principle of energy conservation, it can replenish water to users during peak periods, ensuring that the water in the tank can be compensated to the user's pipe network to a large extent, suppressing negative pressure, and ensuring that it does not affect the municipal pipe network.

control
The non negative pressure water supply system sets a constant pressure value. If the pipeline pressure is higher than the set pressure value, the pressure transmitter will feedback the pipeline pressure to the variable frequency control cabinet. The tap water can be directly supplied to the user's pipeline through the direct supply pipeline. When the pressure of the municipal pipeline network changes or the water consumption of the user pipeline network changes, causing the pipeline pressure to be lower than the set pressure, the pressure transmitter feeds back the pipeline pressure to the PID controller in the variable frequency control cabinet, compares and adjusts the output frequency of the variable frequency converter through the UPC watchdog controller, and starts the water pump unit to adjust the water pump speed to maintain constant pressure water supply; If the tap water source cannot fully meet (or all) the water supply requirements, the central control center will adjust and control the start and stop of multiple power frequency pumps and the speed of variable frequency pumps to meet the water supply requirements of some users.

Non negative pressure technology
The non negative pressure water supply system adopts microcomputer frequency conversion technology and effective negative pressure treatment technology to achieve stacked water supply. The equipment is directly connected in series with the tap water pipeline network through a vacuum compensation system and a fully enclosed structure, and overcomes the adverse effects on the pipeline network. The device collects vacuum degree and water level signals inside the steady flow compensator through pressure gauges, vacuum suppressors, and detection devices in the steady flow compensator. Real time feedback is provided, and special devices in the vacuum suppressors and steady flow compensators are controlled by a microcomputer to suppress negative pressure and ensure that the device does not affect the urban pipeline network.

The direct connection between the system and the municipal water supply network for water intake and pressurization will not create negative pressure on the municipal water supply network. When the water pressure in the municipal pipeline network decreases or even stops, the water pump unit can still work until the change in inlet and outlet time in the steady flow compensator becomes negative (watchdog technology) or a simple low-level control method is used. When the water pressure drops to the lower limit pressure set by the electric contact, it automatically stops and starts up automatically when water comes in. When there is a power outage, the water pump unit stops working, and tap water can enter the user's pipeline network through a direct pipeline. When a call is received, the unit automatically starts up and resumes normal water supply.

Automatic pressure compensation technology
According to the resistance characteristics of the system, the greater the flow rate, the greater the resistance of the system. In order to ensure that the system has sufficient head to overcome system resistance when using large amounts of water, manufacturers can only set the system pressure according to the pressure required for large flow rates. When using small amounts of water, excessive pressure can cause energy waste. The set pressure of the system can be automatically adjusted according to changes in water consumption. When using water at low flow rates, it operates at a low pressure value. As the water consumption increases, the system gradually increases its usage pressure according to its hydraulic characteristics. Thus maximizing the savings of electricity.

1. Energy saving and consumption reducing renovation of the user's original pressurization system.

2. Various types of reclaimed water, sewage, and wastewater treatment plants;

3. Various types of waterworks and water supply booster pump stations;

4. Constant pressure oil transportation systems such as oil field pipelines, oil depots, oil pump stations, and oil ports;

5. Non negative pressure water supply equipment is also suitable for production water in various industrial and mining enterprises (such as circulating cooling water, industrial boiler water supply systems, etc. that require constant pressure production water);

6. High rise buildings, residential communities, enterprises and institutions, and other living and fire water supply systems, HVAC, central air conditioning circulation and quality control


advantage
1. Fully utilize the pressure of the municipal pipeline network, greatly saving energy.

2. Avoid secondary pollution of water.

3. Save floor space.

4. Save investment.

5. Easy to maintain.

6. Save operating costs.

7. Maintain constant pressure.

8. Power outage and continuous water supply.

disadvantage
Non negative pressure water supply has certain disadvantages, as it does not have a water tank. Although it can store water, the amount is very small. Once the municipal pipeline network stops supplying water, users will quickly run out of water. Therefore, when choosing non negative pressure water supply, box type non negative pressure water supply equipment can also be considered. The stainless steel assembled water tank added on the basis of the non negative pressure water supply unit can provide storage capacity from several to thousands of cubic meters to meet the different needs of customers.

Seven major issues with traditional water supply methods
1. Serious pollution: Tap water must first be placed in a pool or tank, which has poor sealing and is often contaminated by debris, stolen goods, and even animal carcasses. It can also produce scale and breed bacteria, seriously affecting the health of users.

2. High investment: It is necessary to build a water tank or reservoir, which incurs high construction costs.

3. Large land occupation: Water tanks or reservoirs need to be built, and the equipment occupies a large space, which will occupy a large amount of commercial land and reduce income.

4. High energy consumption: Due to the fact that tap water must be first placed in a pool or tank and then pressurized, the utilization rate of pressure in the municipal pipeline network is zero, which seriously wastes energy.

5. Serious waste: Most water tanks are constructed with civil engineering structures, which often experience seepage, leakage, and other phenomena. Due to severe pollution, a large amount of water needs to be regularly used for cleaning, resulting in serious waste.

6. Complex installation: Due to the construction of water tanks or pools, the installation is complex and the construction period is long.

7. High maintenance costs: Regular cleaning, disinfection, and other maintenance work are required, resulting in high cleaning and maintenance costs in the later stages.