Using air movers to evacuate NG pipeline

[MTPipeliner]

I'm looking for some information about using air movers (air handlers) to evacuate natural gas from a pipeline. So far I've been able to come up with the AGA purging manual, and parts 1 and 2 of an article titled "Performance of expellers in evacuating gas pipelines". The article and the AGA manual have some pretty contradictory information. The articles seem to have better backup and more complete information, but I'd like some more backup before I feel comfortable saying that the AGA manual is incorrect.

Are any of you guys aware of other documents or references out there that may be helpful?

Any real life experiences? Either good or bad.

Thanks.