Overview of WZG Stainless Steel Non-Pressure-Compensated Variable-Frequency Domestic Water Supply Equipment

WZG stainless steel non‑negative‑pressure variable‑frequency domestic water supply equipment represents a major energy‑saving and emission‑reducing trend in China today. Building on our existing variable‑frequency constant‑pressure water supply systems, we have developed a non‑negative‑pressure solution that fully leverages the existing pressure in the municipal water network. Under the same water demand conditions, it allows the use of pumps and control equipment with lower power ratings, while during periods of low nighttime flow, it can draw directly from mains pressure without activating the pump. Compared with conventional tank‑based systems, this approach significantly reduces both operational electricity costs and capital investment. Non‑negative‑pressure water supply units eliminate the need for elevated tanks or reservoirs, occupying considerably less space and thereby lowering initial equipment costs as well as expenses associated with cleaning and disinfecting such facilities. Featuring a fully enclosed design, these systems effectively prevent secondary contamination, making them an environmentally friendly, next‑generation water‑supply solution. While commonly used variable‑frequency constant‑pressure systems have done away with above‑ground tanks, thereby reducing the risk of secondary water quality contamination, the construction and maintenance costs of underground tanks—and the potential for groundwater contamination they pose—remain significant concerns. Consequently, non‑negative‑pressure water supply technology represents a natural evolution and extension of variable‑frequency constant‑pressure systems.

Negative‑pressure‑free booster water supply equipment connects the pump directly to the municipal water network, using a pressure‑regulating tank as the pump’s inlet storage reservoir and a vacuum eliminator to prevent negative pressure from forming in the distribution system. By fully leveraging the existing pressure of the municipal network and employing a pressure‑regulating tank as the pump’s inlet storage, this system achieves secondary pressurization without compromising the water supply to other users. It eliminates the need to construct additional reservoirs or tanks, ensuring consistent water quality—without secondary contamination—while making efficient use of the network’s inherent pressure. The energy‑saving benefits are substantial, with reductions exceeding 50%. Fully automated and intelligently controlled, the equipment features multiple protection and control functions, enabling truly unattended operation.

Working Principle of WZG Stainless Steel Non-Pressure-Compensated Variable-Frequency Domestic Water Supply Equipment

Tap water enters the regulating tank, and the air inside is vented through the vacuum eliminator. Once the tank is fully filled, the vacuum eliminator automatically shuts off. When the municipal water supply can meet both pressure and flow requirements, the pumping system delivers water directly to the distribution network via a bypass check valve. If the mains pressure falls short of the demand, a pressure sensor (or pressure controller, or electrical contact pressure gauge) sends a start signal to activate the pump. During operation, if the available mains flow exceeds the pump’s capacity, normal supply is maintained; during peak demand, should the mains flow become insufficient, the water stored in the regulating tank serves as a supplementary source, ensuring continued service. At this point, air is drawn into the tank through the vacuum eliminator, eliminating any negative pressure in the mains. Once peak demand has passed, the system returns to its normal operating state. Should the mains supply prove inadequate or the network experience an outage—causing the water level in the regulating tank to drop continuously—the liquid-level controller issues a stop signal to protect the pump unit. During nighttime or low‑flow conditions, a small expansion tank can be used to prevent frequent pump cycling. The key technological components of the non‑negative‑pressure water‑supply system are the intelligent control system (variable‑frequency drive type) and the vacuum‑elimination mechanism of the regulating tank. The core of the intelligent control system employs a Siemens programmable logic controller; its software was meticulously developed by seasoned engineering professionals, drawing on years of expertise in variable‑frequency water‑supply projects and tailored to the specific operational characteristics of the pumps. The equipment features an intuitive interface, simple and reliable operation, stable performance, and a high degree of intelligence. Vacuum elimination in the regulating tank is another critical technology for this project: the seamless integration with the mains network relies entirely on the tank‑mounted vacuum eliminator, which promptly removes internal vacuum when the tank is emptied, thereby maintaining balanced pressure between the tank and the mains and preventing negative pressure from affecting the municipal network or disrupting the normal water supply of other connected users.

Wenzhou

Features of WZG Stainless Steel Non-Pressure Variable-Frequency Domestic Water Supply Equipment

1. By integrating and optimizing multiple advanced technologies, the non‑negative‑pressure water supply system is directly connected to the municipal water network, ensuring stable pressure, energy efficiency, hygienic operation, and reliable safety—without generating negative pressure and eliminating the need for reservoirs or tanks.

2. Hygienic and pollution-free: The equipment features a fully sealed design, preventing bacteria and dust from entering the system; it also inhibits algae growth, thereby averting secondary contamination of the water source and ensuring the quality of the supplied water. Users receive tap water that meets national hygiene standards.

3. Significant energy savings: The fully enclosed design ensures reliable operation, eliminating issues such as leakage, overflow, and dripping, while eliminating the need for water tanks or reservoirs and reducing water consumption for disinfection and flushing. By directly connecting to the municipal water supply network, the system makes full use of the existing water pressure—supplementing only the shortfall—and automatically shuts down when the tap water pressure meets the required level. Most of the time, the non‑negative‑pressure water supply equipment operates at low frequencies, resulting in reduced power consumption. Coupled with variable‑frequency drive technology, further energy savings are achieved, with overall efficiency gains typically exceeding 50%.

4. Reliable operation: It has no impact on the municipal water supply network. The equipment utilizes an adjustment tank to automatically regulate pressure without creating negative pressure, ensuring that when the network is boosted, no negative pressure is generated in the existing system and normal water use by other consumers remains unaffected.

5. Investment Savings: No need to construct reservoirs or water tanks, reducing civil‑engineering costs; no need for zero‑pressure boosting, allowing for more compact equipment selection and lower capital expenditures; the water remains uncontaminated, eliminating the need for purification systems and further cutting investment. The system can fully leverage the pressure of the municipal water supply network, resulting in low energy consumption and reduced daily electricity expenses. With no water tanks or reservoirs, it also saves on the costs of routine cleaning and disinfection.

6. Flexible electrical configuration: The electrical control system can be implemented either with variable-frequency constant (or variable) pressure control, or with direct pressure control (BZG pneumatic type).