【正文】 然而，吸氣閥不能解決建筑排水系統(tǒng)和通氣系統(tǒng)中瞬時正壓傳播的問題，污水管網(wǎng)中自由水流或遠處產(chǎn)生的瞬時正壓的到達通路間歇的關閉，有可能順。在過去20年里，吸氣閥（AAVs）的發(fā)展給設計師提供了一種緩解瞬時負壓的方法，如在隨機的潔具排水過程中，吸氣閥有助于系統(tǒng)中水力條件的恢復。這種方法盡管既被證明了，也是傳統(tǒng)的，但也有其內在弱點，如通氣管末端較遠[7]，導致了綜合樓緩解反應到達較遲和敞開屋面立管末端內在的多樣性。6．排入管網(wǎng)的水7．立管1底部排水8．瞬時氣壓強加于污水管9．水封的振動和保持——密封建筑排水和通氣系統(tǒng)的可行性――瞬時氣壓的控制和抑制作為系統(tǒng)操作的自然結果，建筑排水系統(tǒng)和通氣系統(tǒng)內部產(chǎn)生的氣壓瞬變對于水封破壞和交叉污染的可居住空間來說也是可靠的。關鍵詞：活性氣壓控制，存水彎保持，瞬變傳播。這種模擬實驗在水封不被破壞，系統(tǒng)壓力得以維持的條件下，能夠辨認活性氣壓控制設備的作用。s and sinks. 10. Conclusion—viability of a sealed building drainage and vent systemThe simulation presented confirms that a sealed building drainage system utilizing active transient control would be a viable design option. A sealed building drainage system would offer the following advantages: ? System security would be immeasurably enhanced as all highlevel open system terminations would be redundant.? System plexity would be reduced while system predictability would increase.? Space and material savings would be achieved within the construction phase of any installation.These benefits would be realized provided that active transient control and suppression was incorporated into the design in the form of both AAV to suppress negative transients and variable volume containment devices (PAPA) to control positive transients. The diversity inherent in the operation of both building drainage and vent systems and the sewers connected to the building have a role in providing interconnected relief paths as part of the system solution. The method of characteristics based finite difference simulation presented has provided output consistent with expectations for the operation of the sealed system studied. The accuracy of the simulation in other recent applications, including the accurate corroboration of the SARS spread mechanism within the Amoy Gardens plex in Hong Kong in 2003, provides a confidence level in the results presented. Due to the random mode of operation of building drainage and vent systems further simulations, laboratory and site investigations will be undertaken to ensure that the concept is wholly viable. 32中文譯文：密封的建筑排水系統(tǒng)和通氣系統(tǒng)——活性氣壓的瞬變控制和抑制摘要由于通過成對的吸氣閥和正壓衰減器與管網(wǎng)中的立管互相連接能控制和抑制活性氣壓瞬變，因此在綜合樓中采用密封的建筑排水系統(tǒng)和通氣系統(tǒng)被認為是一個可行的提議。s, airflow is driven up stack 1 towards the PAPA connection. However, as the base of the other stacks have not a yet had positive sewer pressure levels imposed, a secondary airflow path is established downwards to the sewer connection in each of stacks 2–4, as shown by the negative airflows in Fig. 8. As the imposed transient abates so the reversed flow reduces and the PAPA discharges air to the network, again demonstrated by the simulation, Fig. 8. This pattern repeats as each of the stacks is subjected to a sewer transient. Fig. 9 illustrates typical air pressure profiles in stacks 1 and 2. The pressure gradient in stack 2 confirms the airflow direction up the stack towards the AAV/PAPA junction. It will be seen that pressure continues to decrease down stack 1 until it recovers, pipes 1 and 3, due to the effect of the continuing waterflow in those pipes.The PAPA installation reacts to the sewer transients by absorbing airflow, Fig. 10. The PAPA will expand until the accumulated air inflow reaches its assumed 40s. The entrained airflow in pipe 1 reduces to zero at the stack base and a pressure transient is generated within that stack, Fig. 6. The impact of this transient will also be seen later in a discussion of the trap seal responses for the network. pressure levels within the network during the . discharge phase of the simulation. Note surcharge at base stack 1, pipe 1 at . It will also be seen, Fig. 6, that the predicted pressure at the base of pipes 1, 6 and 14, in the absence of surcharge, conform to that normally expected, namely a small positive back pressure as the entrained air is forced through the water curtain at the base of the stack and into the sewer. In the case of stack 4, pipe 19, the reversed airflow drawn into the stack demonstrates a pressure drop as it traverses the water curtain present at that stack base. The simulation allows the air pressure profiles up stack 1 to be modelled during,and following, the surcharge illustrated in Fig. 6. Fig. 7(a) and (b) illustrate the air pressure profiles in the stack from to s. Fig. 5 illustrates the air pressure profile from the stack base in both stacks 1 and 4 at s onwards, the reversed airflow initially established diminishes due to the traction applied by the falling water film in that pipe. However, the suction pressures developed in the other three stacks still results in a continuing but reduced reversed airflow in pipe 19. As the water downflow in pipe 19 reaches its maximum value from 3mm. In addition, the simulation replicates local appliance trap seal oscillations and the operation of active control devices, thereby yielding data on network airflows and identifying system failures and consequences. While the simulation has been extensively validated [10], its use to independently confirm the mechanism of SARS virus spread within the Amoy Gardens outbreak in 2003 has provided further confidence in its predictions [12]. Air pressure transient propagation depends upon the rate of change of the system conditions. Increasing annular downflow generates an enhanced entrained airflow and lowers the system pressure. Retarding the entrained airflow generates positive transients. External events may also propagate both positive and negative transients into the network. The annular water flow in the ‘wet’ stack entrains an airflow due to the condition of ‘no slip’ established between the annular water and air core surfaces and generates the expected pressure variation down a vertical stack. Pressure falls from atmospheric above the stack entry due to friction and the effects of drawing air through the water curtains formed at discharging branch junctions. In the lower wet stack the pressure recovers to above atmospheric due to the tract