Fun with numbers (venting)

ryanr256

According to the numbers, leg one of my main has 1.1 cubic feet of capacity and leg two has 1.3 cubic feet of capacity.



I have two Hoffman 75's on the end of each leg, giving a venting capability of 1.000 cfm @ 1 ounce of pressure for each leg.



According to the numbers, my mains should vent in just a tad over one minute. But, it takes almost exactly 4 minutes from when the header is hot until the antlers get hot and the vents close. Once the header is hot, my gauge flutters between one tenth and two tenths of a pound.



Why don't the numbers work?



:-)



-Bob

jpf321

you will never

attain minutes to vent numbers unless all your pipes are already steam hot. most of the 4mins is spent bringing pipes from 70 deg to 215 deg and in the meantime robbing your steam and needing to replace it with new steam...this is known as steam creep.if all your pipes were already at 215 there would be no robbing of steam to heat up the pipes

ryanr256

D'oh!

Ah, thanks for the enlightenment. I see it now. Maybe I should do the open pipe test to see how long it takes for the steam to get to the end of the main without a vent.



The good thing is that both legs get hot within a few seconds of one another. The radiator vents are my next project.



Thanks again,



-Bob

jpf321

if you do an open...

pipe test .. make sure the pipe has a ball valve shut off on it .. so that when the steam gets there you can shut the open pipe down quickly and safely. the ball valve needn't be expensive, just anything that threads on the pipe and allows you to shut it with one easy movement.