Double-chamber control mechanism of backflow preventer based on differential pressure principle

Abstract

The invention relates to a double-chamber structure of a differential-pressure-principle backflow preventer. The double-chamber structure of the differential-pressure-principle backflow preventer comprises an inlet valve flap, a control chamber, a piston, a spring, a spring seat and a valve rod. The inlet valve flap, the control chamber, the piston, the spring and the spring seat are sequentially connected together through the valve rod; the inlet valve flap is arranged on the left outer side of the control chamber, can slide left and right and is fixed onto the left free end of the valve rod through a fastener; the inlet valve flap is evenly provided with water through holes in the radial direction; the piston is fixed on the left side of the valve rod and slidingly arranged inside the control chamber; the spring seat is fixed on the right side of the inside of the control chamber; the spring is arranged between the spring seat and the piston, and the piston abuts against the right side of the inlet valve flap through the pressing force of the spring. The double-chamber structure of differential-pressure-principle backflow preventer aims at eliminating the mechanical losses at the inlet when overcoming the spring resistance but only leaving medium overflow losses, thereby reducing the head losses by more than 4 m; when the medium flow velocity is 3 m / s, for backflow preventers of different draft diameters, the head losses can be kept at 30-40 KPa (3.5-4 m water heads), so that great energy saving effects can be achieved.

Description

technical field [0001] The invention relates to a pipe network control valve, in particular to a double-chamber control mechanism of a backflow preventer based on the principle of differential pressure. Background technique [0002] In water supply and drainage and various water supply fields, the installation of backflow preventers is a mandatory requirement in the code. It is a hydraulic control device installed at the cross-connection of drinking water and non-drinking water pipe networks. Strictly control the flow of pressurized drinking water only in one direction to ensure zero backflow, ensure the safety of water supply, and protect the health of the people. [0003] Such as image 3 and Figure 4 , The typical structure of the existing domestic and foreign backflow preventers is composed of an inlet check valve 4', an outlet check valve 5' and a drain valve 6'. There are three representative domestic and foreign product standards: American Standard ANSI / AWWAC511 "...

AI Technical Summary

Problems solved by technology

[0005] Although the existing anti-backflow device can achieve the goal of zero backflow, it needs to consume the 4m water head loss of P1 to overcome the spring resistance and enter the intermediate chamber during operation, so as to achieve the purpose of anti-backflow of P1-P2>14KPa. This anti-backflow method is not energy-saving enough. The preload loss of the water inlet spring is greater than 14KPa, and as the opening of the disc increases, the compression of the spring also increases. According to Hooke’s law, the mechanical loss caused by this resistance and compression also increases. It increases linearly, and the loss during operation can reach 40KPa (4m.H2O). In addition to the overcurrent loss of the medium in the valve body, in practical applications, the local head loss is above 8m.

However, such a large energy consumption has become a technical problem that is difficult to solve and is expected to be solved at home and abroad.

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