"For external use only"
On 7/7/2020 4:48 PM, ch...@wbmfg.com wrote:
In Utah, we are fortunate that we can trade duct and fiber with UDOT.
So if I am building, I put in 4 ducts instead of 1 and let UDOT take
temporary ownership of 3. That 4 pack of 1.25 " HDPE SDR11 is called
a 1D by UDOT.
If I put in a mile of 1D, I get 3 miles of credit to use their ducts
elsewhere. They even have a conversion factor to use their strands of
fibers in exchange for duct too.
So, if you are doing one of these jobs it has to built to their
specs. That drives the cost up a bit. They have to have their own 24
x 36 x 36" handholes. Concrete bottoms. Drain holes. Foot of gravel
under. 3/4" 8' ground rod. Grouted conduits. Locate balls.
Carsonite markers. Customized plates on the lids. They have to have
tonable mule tape installed in each duct. They have to witness
proofing the duct.
So, I created a proofing mandrel that is made out of PTFE so it is
really low friction and has a beveled end to push through tight
spots. It also has a buna rubber cup seal at the back to get as much
push from the air as possible. It has an eye bolt so it can drag the
mule tape with it.
A one pass deal where before you had to blow jet line, then use that
to pull mule tape, then use the mule tape to pull an aluminum proofing
mandrel then go back and put the mule tape back in when you were done,
possibly having to blow jet line in again because mule tape is
difficult to blow. It tends to bunch up.
That dart comes rocketing out at what looks like 150 mph. So I made a
dart catcher. Larger tube. Air holes. 5 inches of extruded
polyethlyene foam in the bottom. Slid the whole thing over the end of
the duct you are proofing and nobody gets killed by the dart.
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