Calculating Exhaust Back Pressure

[PAFred]

Does anyone know where I can find a chart or spec's on how much back pressure is created by pipe diameters, elbows and 45's and 90 degree elbows. I'm trying to create an automatic calculator to provide both for my self and comrads at work to ensure gen set start ups are properly done.

 

[alehman]

GT Exhaust Systems has a calculator program. I think you can get it from their web site or by calling.

Alan
----
"It’s always fun to do the impossible." - Walt Disney

 

[davidbeach]

Often I find myself admonishing mechanicals to consult with an electrical engineer; in this case you need to hire the services of a mechanical engineer. Exhaust is only one of several things that need the attention of a mechanical engineer.

 

[rmw]

One who knows how to use Crane Technical Paper 410.

rmw

 

[alehman]

David,
That is a good point. If the OP, who is listed as electrical, is asking such basic questions, he should retain the services of a qualified ME.


Alan
----
"It’s always fun to do the impossible." - Walt Disney

 

[TheBlacksmith]

When I was with a large genset OEM, we had a program to do just that. Ask the OEM if this is a new installation, they have a vested interest in getting it right. We had many service calls for poor performance that were directly caused by poor exhaust design, poor intake design, or poor cooling air flow to the radiators/intercoolers.

 

[alehman]

Yes, poor cooling air flow and inadequately sized radiators are common problems. Problems are especially severe where sound attenuators with high restriction are required. Typical set-mounted radiator fans are rated for only 0.5"w.c.

I rarely see exhaust pressure problems except with long runs or unusual configurations. I did see a wadded-up flaming tarp blow out of an exhaust stack on a load bank test one time. I suppose that's an unusual restriction.

Alan
----
"It’s always fun to do the impossible." - Walt Disney

 

[catserveng]

I have used the GT Systems calculator, works pretty good. CAT has a good set of calculations in their current EPG Application and Installation Guide. Your local CAT Dealer should be able to provide you a copy. Also CAT has a handy guidebook, Engine Installation and Service Handbook, form number LEBV0915, and the exhaust back pressure section in it is also very good.

Before I left my last job, exhaust backpressure was becoming a "hot topic" (no pun intended) again with the requirements to add particulate traps.

Hope that helps