TheSeatNegativePressureBCGValvePassiveAGSScomesasapartofthenegativepressurereliefvalveinthemoduleofthepassiveAnestheticGasScavengingSystem(AGSS)intheBreathingCircuitGas(BCG)o fananesthesiadeliverymachine.ExcessfreshgasreleasedfromthebellowsandthegasesthatareexhaledfromthepatienttransferfromtheexhalationvalvetotheAGSSmoduleandarescavengedsuchthatthe possiblelongtermhealthhazardsfortheexposedmedicalstaffiseliminated.Theseatofthenegativereliefvalvepreventsgasfrombeingpulledoutofthebreathingcircuit.Ifmorethanasmallamountofnegativepressureisappliedtothescavengingsystem,theseatofthereliefvalveopens,allowingroomairtobedrawntothescavengingsysteminsteadofpullinggasfromthepatientcircuit.Itismadeofthepassivatedstainlesssteelwhichishighly corrosionresistantdespitecomingintocontactwithgasesthatarelessthan300psi.