No negative "refers to produce negative pressure or not. But we usually say" negative "refers to the atmospheric pressure condition (i.e. below 1 atmosphere of gas pressure) or in airtight system under the vacuum pressure, also known as the vacuum with straw. For example, drink, the straw is negative; pumps, the impeller inlet pressure; the seal is formed when opening canned food" unshaven ", is also negative phenomenon; close ChongCe flush valve, is to use water pressure technology; from siphon ink pen, the life breath, also use negative pressure system (such as... airtight container, pipe or specified closed space) of gas pressure below atmosphere, namely, the negative pressure produced by "vacuum" size usually said.
"No negative" is relative to the "negative", refers to the space within the scope specified in the open and closed system (including the pressure below), the state environmental pressure is normal in "system" or "positive pressure" state. In the study, "without the fluid pressure" concept was first put forward in the field of pressure vessels, the background is in order to make a liquid medium pressure produced by shaking containers not sealed containers that are flat or flat flat in containers or system pressure increases, and elimination of suction device to eliminate past only a simple mechanical valve, such as the respiration valve, etc. "No negative" term used to secondary water area began in 1995 Qingdao three group Co., LTD. (the original factory automation of water LinQu without pressure water equipment), and the first developed in 1997, the first set of no negative supply equipment.
According to the work principle of centrifugal pump, the centrifugal pump impeller water runs from the flow of import and export of the process of converting speed can water pressure, and the output of the outlet pipe, because of the impeller inlet water discharge and forming a vacuum pump, or low water pressure in the role of the (or inhaled) press, then, the import of impeller rotating impeller is continuously, and thus the suction pump working process. Therefore, in the process of running water pump suction "existence", will cause the import of negative pressure produced over net, harm, mainly for:
It will cause the spring-up of pipe pressure drop, affect local near the water users. This is department of municipal water supply pump pumping directly to prohibit the reason.
2 May cause other string over the nets ", "water pressure backflow.
In addition, when (suction pump, excessive can also cause water pipe (water hammer, gas resistance, pressure oscillations, he burst, etc.), pump net (cavitation) and other parts of the water damage, or security hidden danger.
Therefore, in 1994, the state council makes the 158 the urban water supply regulation stipulates: "prohibited in urban public either horzontally directly pump pumping". Since then, who need to secondary compression supply must take pool, cistern, or indirect pressurized water supply water Wells, also is the pump must from pool, tank or water well water adjusting device (for) the atmosphere in airtight water pressure, the purpose is to avoid direct connect supply pressure of pump will connect to the negative influence of network.
So, in the field of water supply, urban secondary municipal water pipe (or urban water supply network, public water supply network) are not allowed in the direct connect pump suction pump. However, the traditional way of secondary compression water pool, tank facilities easily cause water pollution, if not regular cleaning and disinfection and mismanagement etc drinking water easily, the secondary pollution, water pipe pressure also cannot use original, And along with the time development and technical progress, municipal water supply capacity and water pipes have greatly improved conditions for drinking water, the people of the secondary pollution, deepening understanding of severity and pay more attention to the importance of saving, therefore, the traditional water pressure tank from pool, the second mode has not conform to "prevent water pollution" and "energy" aspects of water supply demand. Hence, a new kind of secondary compression in water supply has become second technology is a new field of study.
"Without the pressure of water technology research and application was solved this problem, because this is how to solve the core technology of pressurized water supply pump directly after the negative problems, in order to achieve safety and reliable and effectively preventing water pump running on the string of the negative effect produced water pipe, the realization of" no direct water-supply pipe pressure "booster.
Therefore, in the field of water supply, "no negative" refers to the use of science and technology and the measures to eliminate pump operation in its string of water supply network of its negative influence, not negative pressure produced water pipe, do not affect the water near the user, no pollution, and protect the water quality and water supply network directly the string of water supply and water.
The negative pressure water (reproduced on technology"