When we run an SIP of the transfer line during the cool down step we have the line pressurized to 0.3 bar and we have two valves open to the drain to remove the condensate from the line. There is a thermostatic steam trap and check valve between the open valve and the drain. We allow the transfer line to cool for twenty minutes which allows the line to cool to around 50 degrees Celsius. We are getting contamination of our product, one suggestion is to close the valves to drain during cooldown and keep the transfer line pressurized to 0.3 bar. This will allow build up condensate, is this a large problem in keeping sterility.