Larry Jaques fired this volley in
:

On Sun, 15 Feb 2015 15:49:04 -0600, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:

I've dug around for quite a while, and although I find all sorts of
"comforting" diagonal data about fall heights, column separation, etc,
I cannot find a stated vacuum rating for ASTM D2729 pipe (4").

Holey pipe? Por que?
It comes in solid, too.


I'm getting ready to re-do a poorly-designed vacuum hold-down system
for a ShopSabre 4896 that has only ONE 2" pipe to each half of the
table, even though the pump has a 4" inlet!(duh!)

The 4" has 4x the area of a single 2", so you're at the halfway point.
What pump is on there now?

20HP 3-phase regen blower; it'll pull 11" at many, many CFM


4" water pipe (sch 20-40-80) is slightly too large to fit in the space
provided, but 4" ASTM-D2729 sewer pipe will fit. We're only talking
11" of vacuum (or -5.4psi). But I want some margin of safety, and
can't find a figure anywhere.

Does the ShopSabre have specs on CFM of flow for those? Measure the
holes, add 'em up, and figure the area at 2 pi r2. Finding data for
figuring vacuum by leakage area ought to be tricky, though.

You mean, there's a formula for area?
Maybe that's where they screwed up!

1/2" MDF, -0.040" 'deglazed' on both sides, and edge-sealed, all-around.
It's sort of the standard for this kind of machine, doing full-sheet
work.

This stuff must not come over in anything close to the order posted. I
posted all that stuff yestiddy.

I'm pretty competent at vacuum work, too. I just want to know if anyone
has ever seen a vacuum spec for 2729.

Lloyd