In an early post this morning, I discussed the need for “rain caps” and “weep holes” on our Pressure Safety Relief systems. And a dear friend and great ChemE reminded me that “weep Holes” are not just for draining rainwater. For example, this week I was working with an NH3 client, and I must state that NH3 gas can absolutely condense into liquid in the vent discharge piping after a Pressure Safety Valve (PSV) closes.