Calculation of Steam Loss

[newengr]

I was wondering what was the equation or how to calculate for steam loss through a leak in a pipe? For ex. A pipe that is 50ft in length, hole size is .25in, steam at 240psig?

 

[TD2K]

I do it typically as an orifice. In this case, you will have chocked flow through the orifice as the dP is greater than about 1/2 of the inlet absolute pressure. Crane's Technical paper 410C does a good job walking you through a couple of cases.

I'll initially make the assumption that the steam header can supply the flow to the leak. Once I calculate the leak flow rate, I'll check that assumption. If the piping pressure drop losses from the 'source' to the leak are significant, you might have to run through the calcs a few time to zero in on the final answer.

You can even guesstimate the answer if the header effect is significant by assuming that the change in flowrate through the leak, for sonic flow, is directly proportional to the inlet pressure (actually, inlet density but for steam in this case, that's pressure).

 

[vpl]

TD2K

Just want to check - Crane's 410C that you refer to - is that the "Flow of Fluids through Valves, Fittings, and Pipes"? My copy just says "technical paper #410" -- without the "C" at the end.

 

[TD2K]

Same one, I thought there was a C there but you're right, it's just 410. Nope, I don't have a later edition

 

[TBP]

Spirax Sarco's "Hook-Ups" has a chart for steam losses from orifices of various sizes and pressures.