No idea. Has to do with atmospheric pressure I presume. Some magic number
inherent to venturies.
From: Adam Moffett
Sent: Tuesday, May 23, 2023 6:23 PM
To: AnimalFarm Microwave Users Group
Subject: Re: [AFMUG] Air vac
Splitting the pipe into two equal pipes will double the area for the air to go
through. Based on the formula I found yesterday that should be the same
pressure but half the velocity. I still think you'd want to maximize the
product of cfm times velocity, I'm just not sure what would achieve that.
It also looked like the pressure differential created by the venturi effect was
related to the delta of the squares of velocity in and before the constriction.
(Va^2 - Vb^2). I don't see how 72psi would maximize that, but I guess that's
why I don't have a PhD.
On Tue, May 23, 2023 at 1:47 PM Steve Jones <thatoneguyst...@gmail.com> wrote:
I dont know the math behind air pressure, but if I split the 150psi into two,
then does each orifice get 75psi?
On Tue, May 23, 2023 at 9:54 AM Chuck McCown via AF <af@af.afmug.com> wrote:
Spoke to a venturi engineer just now. He says 72 psi is the magic number.
It has something to do with atmospheric air pressure and the density of the
air. I presume that number would change with altitude.
From: Steve Jones
Sent: Monday, May 22, 2023 9:34 AM
To: AnimalFarm Microwave Users Group
Subject: Re: [AFMUG] Air vac
I use an auger to dig them, vac to clear them. Same thing with the
airspade/airvac combo. I dont do posts less than 48 inches. Whats really
pushing this is the last project was installing 2 inch duct for the power
company, the old primaries were failed concentric, as it turns out the stuff is
dangerous, it faults on its own, jabbing shovels and post hole diggers at it is
a recipe for disaster and water is its mortal enemy. Im chasing more contracts
with that power company to replace more of that concentric. Im not gonna get
the cutting power of water, but ill have dry spoils to put back in the hole.
I wish I hadnt done all the drugs, id be able to understand the maths on
this, im wondering if I cant split the input and double the lift with two
venturis
On Mon, May 22, 2023 at 9:23 AM <dmmoff...@gmail.com> wrote:
So you dug post holes with a shop vac? Is it sandy where you are? I
feel like I hit about 10,000 rocks per post hole. Many too big for a vac hose,
and many just big enough to clog it.
I might have to try it anyway.
From: AF <af-boun...@af.afmug.com> On Behalf Of Steve Jones
Sent: Sunday, May 21, 2023 6:12 PM
To: AnimalFarm Microwave Users Group <af@af.afmug.com>
Subject: Re: [AFMUG] Air vac
I'm having better luck with the prototype than a shop vac already, just
trying to improve the lift. Toting a generator isnt really an option.
I also just have a shop vac hose, if theres moisture the dirt collects on
the sides with a shop vac and loses lift. That's how I've always dug post holes.
On Sun, May 21, 2023, 3:53 PM Chuck McCown via AF <af@af.afmug.com> wrote:
I think you would have better luck with a strong shop vac and a 30
gallon drum. I have seen guys do that and it worked OK. Air powered vacuum
producers work but I don’t know how well. Sometimes they are called eductors
or ejectors.
Take a look at this one:
https://www.globalindustrial.com/p/2-in-line-vac-only-aluminum?infoParam.campaignId=T9F&gclid=CjwKCAjwgqejBhBAEiwAuWHioM68tuz0PVLcvHFy4CRspRtvhy5gEQQryMrUkOoNv4MVeUTRSWTkvxoCrv8QAvD_BwE
Best Regards,
Chuck McCown
McCown Technology Corporation
8401 N Commerce Dr
Lake Point, Utah 84074
801-250-9503 Office
435-830-4306 Cell
www.mccowntech.com
www.microtrench.pro
www.terabitnetworks.com
From: Steve Jones
Sent: Sunday, May 21, 2023 11:56 AM
To: AnimalFarm Microwave Users Group
Subject: [AFMUG] Air vac
I need advice from you nerds.
I'm a broke joke, so hydrovac isnt in my budget. Besides, I want dry
spoils to put back in the hole.
This revision works for venturi. I have multiple size reducer but right
now I'm just doing 3/4 to to inch. The 3/4 to 1 then 1 to half back to 1.5 for
the venturi side seemed to have the best lift, but the hardware store didnt
have everything, so it's all in 2 inch right now
I'll dump to a 2000lb peanut sack if I can find one, but for now I'll
just use a 30 gallon drum and dump on the mega movers.
This is for use in conjunction with the airspade I did have some coin
to get.
Venturi math gets complicated and I'm full retard so I need to find he
best ways to increase negative pressure and where to drill the ports.
I also wonder if theres an option to recapture the exhaust into the
airspade.
I need you nerds to go full geek.
If I can get valves correct I'll have the local machinist make me a
couple that are pressure rated.
This is to mimic the airvac I also cant afford.
This proof of concept has the lift to clear potholes and handholes,
but I need to clean it up and get more efficiency.
A side discovery is that this setup is perfect for blowing straw and
seed with glue
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