Home made horizontal milling machine.

[tonyfoale]

Hi Tony,
I've seen cheap anemometers on sale around $40.00, obviously not best quality but if repeatable results would be OK for a yes or no on flow improvements.

Why settle for a "yes/no" when it is no more expensive or more work to get some actual repeatable numbers. A bench that I built a long time ago for almost nothing, which used my smallish shop vac missing the filter, and for which I still have tested items gave results better than 1% when compared with my current machine. The only thing wrong with using simple manometers is that testing takes longer and results have to be either entered manually into software or you have to do it all manually.

click to enlarge.

This was much later than my first bench but it is about as simple as it can be, but that does not detract from its accuracy. Note that even though this was all manual I still had a weather station there to calculate correction factors. Sometimes for budget reasons you have to make or use "yes/no" equipment but there really is no need for that with a basic flow bench. Having said that, there is a difference between getting accurate data from any testing programme and how closely that data represents reality. This is never more true than with flow testing. You take static flow measurements whereas reality is rapidly irregularly pulsing flow with liquid being injected into the stream.

[crazypj]

Hope this 'conversation' isn't messing up thread?
I've read a lot about flow benches over the last 50+ yrs (Mostly by D. Vizard ,LOL) I always wondered about valve haed shape, at very fast lift couldn't it create something of a vacuum behind it or would pulse pressure in port tend to pressurise entire port at a resonant frequency? (when it comes 'on the pipe' )not expecting reply right now, I think your about 6 hrs ahead so it's about 1:40am in Spain? My brother in Britain used to call around 7~8:00 am British time, 2~3am in Florida. I never could get him to understand the time difference

[tonyfoale]

Hope this 'conversation' isn't messing up thread?
I've read a lot about flow benches over the last 50+ yrs (Mostly by D. Vizard ,LOL) I always wondered about valve haed shape, at very fast lift couldn't it create something of a vacuum behind it

The velocity of valve heads is actually quite low as is the displacement. There will be some reduced pressure but it will be minor.
Valve head shape is very important for flow though.

You might find this of interest Some flow tests