1. The purposes of the two are different. 


The purpose of the exhaust valve pit: For underground pipelines and underground conduits (such as water supply, oil, natural gas pipelines, etc.), the valves are set up in a kind of small room-like pit (or well) to facilitate the opening and closing of some pipeline operations or maintenance work when necessary. 

2. The purpose of the sludge discharge valve pit: Install and arrange valves and other components in this pit, which is convenient for regular inspection, cleaning and pipe疏通， serving as a key measure to prevent pipe blockage. 






II. The composition classifications of the two are different. 


1. Composition classification of exhaust valve wells: The composition classification of exhaust valve wells includes micro exhaust valves, composite exhaust valves, and sewage composite exhaust valves. 


2. Composition and classification of sludge discharge valve wells: The hydraulic control valve is a valve for water pressure control. The hydraulic control valve consists of a main valve and its accompanying conduits, guide valves, needle valves, ball valves, pressure gauges, etc. Depending on the different purposes, functions and locations, it can evolve into remote-controlled float valves, pressure reducing valves, slow-closing check valves, flow control valves, pressure relief valves, hydraulic electric control valves, pump control valves, etc. 
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III. The requirements for the two are different. 


Requirements for exhaust valve wells: The connection between the valve well shaft and the well body, as well as the well cover, must be reliable. It should not allow water to seep into the well chamber due to heavy rain or water accumulation. The valve well is buried underground and has to withstand various pressures from different directions, as well as corrosion and damage from different chemical substances. It is also required that its pressure-bearing capacity and resistance to acid and alkali corrosion should be good. 






2. Requirements for sludge discharge valve wells: The valve wells themselves must not allow water to seep through and must ensure their sealing performance. When the buried valve well pipes are quite large and buried very deep, cast iron valves (such as stop valves, butterfly valves, etc.) are generally used. Cast iron valves, when exposed to water for a long time, may affect their service life or cause fractures. Therefore, the requirement for sealing performance is even higher.