Gap Between Drip Pan Elbow and Vent Line

Zoso

I have a steam relief valve piped into a drip pan elbow like the one shown on the attachment. When the valve lifts, a large amount of steam escapes through the gap where the vent line goes over the elbow pan. I think this is a symptom that the vent line is undersized, but I don't want to go off on that tangent. My question is, why do we need that gap? The bottom of the elbow is drained, so any water that runs back will drain from the bottom. Wouldn't a drained elbow with the vent line hard-piped to it serve the same function without the possibility of steam escaping (other than through the drain) like I have now?

bob_46

You need the gap to prevent the vent line from putting any strain on the relief valve . That's the reason drip pan elbows exist .