Touching Bases and Responding to Comments after a Busy Couple of Weeks

Well, I’ve had a busy couple of weeks and not done a very good
job of posting;  my apologies there.  Hopefully, I can
catch up a bit over the next few days.  Work’s been busy, but
I’ve also become a grandfather for the third time, which is pretty
much fun.  Here is a picture of our new arrival, Piper, with
her big (and very excited and helpful) sister Arabella.  Kinda
helps keep what matters and what doesn’t matter so much in

Meanwhile, I noticed that several of you had commented on
several different posts, and I thought I had responded.  But
Thursday, we discovered that for some reason, my responses were not
uploading.  A couple of other folks discovered a similar
problem and the IT guys are looking into it. Until then, I
figured I would just repost my comments as a blog post since that
seems to be working O.K.

On March 11, Andrew commented to say that he had found the post

Parallel Pumps; An Indicator of a Retrocommissioning
to be helpful.   First, I’m glad it
was helpful and I appreciate the kind words.  But, I wanted to
mention that there is a new design brief in the works on Pump
System Troubleshooting
that should be available on the
Energy Design
web site very soon.  I know it is complete and
ready to go, I just don’t know when it will be actually posted, but
I’m trying to find out and will post that information when I hear
back.  I mention the brief because it was written as a
companion document for the
Centrifugal Pump Application and Optimization
brief that I
mentioned in the post Andrew responded to.  The new brief
picks up where the application brief left off and looks at a number
of actual field problems and their resolution, most of which are
related to parallel pump applications. So, keep an eye on the
EDR site and eventually you will find it there. EDR is a good
site to monitor anyway as they are always publishing
new information in the form of design briefs, software tools,
and  interactive  learning modules related to our

Justin Clark of San Diego also commented on March 11, but his
comment was with regard to my little foray into video production
titled Flow
Visualization; Lessons in Duct Flow Patterns from my Wood
.  He postulated that the swirling pattern
may be the result of negative pressure in the dead end of the
system beyond the Y joint and postulated that a relief vent or some
other type of opening in that portion of the system would eliminate
it.  In a sense, Justin’s theory is supported by the little
experiment that I mention where I open one of the other blast gates
in the system that is upstream of the fitting and the phenomenon
seems to disappear.  I suspect my little system is not
perfectly air tight and the difference between no up stream blast
gates open and having one open is really a difference between a
little bit of flow and a lot of flow.  And the reality is that
for me, the weird flow and related turbulence do not represent a
problem.  In contrast, if I open a second blast gate, it has a
major impact on the flow through the branch serving what ever tool
I am using, making the dust collection must less effective, so
I simply don’t worry about the weird flow and only run with one
blast gate open.

But, if my duct collection system was an industrial process
handling a material  that tended to clump up, then the
swirling pattern could lead to a build up of material in the
inactive branch.  This could lead to other problems like:

Obstructing flow in the inactive
branch when it came on line or even in the active branch.

Accumulating potentially hazardous or
even explosive material in the collection system.

Making the performance of the fitting
which could exacerbate some of the
other problems.

So, while for me, the turbulence is a bit of a
non-issue in terms of having a working system, it certainly gave
me, and maybe you, something to think about in terms of the things
I think about when I design a duct system.

On March 21st, Tom commented on the educational aspects of the
flow visualization post, noting that I would have never noticed
this had I not had the clear pipe and wondering where I got it so
he could make some educational toys for his kids to play
with.  The pipe seems to match the dimensions for standard PVC
pipe in terms of working with those type of fittings.  But
I’ve never seen clear pipe in any retail stores.  I just
happened to stumble into it when I bought a little dust collection
kit from Sears.  The
current version of the kit
is a bit different from what I
bought, but still seems to have the clear pipe and fittings, so
that might get you going on the projects for your kids. 

I also know that some of the piping sold for acid waste systems
is clear; the last time I did that I was working with glass
pipe.  So, maybe investigating those product lines would be
another resource, but I suspect a very expensive approach compared
to just buying the Sears kit.  A little Googling around
revealed a website
dedicated to clear plastic pipe
, which might be another option,
but also appears to be a bit more expensive than the Sears kit
because you would be buying longer pieces whether you wanted them
or not.  But, they offer a variety of fittings, so you would
have more options in terms of what you put together.

Tom’s question also took me on a little trip down memory
lane.   When I was a kid, one of my favorite toys was my
Building Set
.  My brother and I spent hours putting
together sky scrapers, bridges, and other structures with
working elevators, spinning radar antennas and all sorts of other
features.  But I have to admit that I was a bit jealous
of the
Kenner Hydrodynamics
set that my friend Louie Haffer had. 
With it, we could build piping systems that let us pump water all
over the place (including onto the living room carpet, which may
explain why I never quite talked Mom into letting me get one) using
clear tubing and tanks, little motorized pumps, and barbed fittings
just like the ones that pet stores sell for aquariums.

What’s really exciting is that in Googling around for the links
above, I discovered that there is a toy called Girder and Panel that you
can purchase today that is the current version of the Kenner
product line!  I think I know what Jakie, Arabella, and Pipe
are getting for Christmas or a birthday at some point.  Maybe
Tom’s kids too if he finds his way back to this post or made the
same discovery I did.  And while I suspect you could make a
video game of some sort that let you put things together and pump
virtual liquids about (thus saving the carpet),  I think there
is some real value to be achieved for your kids by having them put
things together with their little hands in three dimensions,
something that they can’t really pick up from an interactive
video.  I actually think the two together could be a real
winner;  the building sets to develop hand-eye coordination
and the videos to convey the science behind them.

Last but not least, SonyaSunny wrote to simply say thanks for
the article on
damper testing
, that she enjoys reading the blog and to have a
nice day.  Thanks back to you SonyaSunny, for taking the time
to read and write;  I have to warn you that you are
encouraging me to post more often, but maybe that’s a good
thing.  Incidentally, since I wrote that post, I found
that the Honeywell
Gray Manual
is available for free on line.  I mention it
because it has a good chapter on damper sizing that you may find
useful if you are interested in damper performance and

As for having a nice day, I’m doing just that as I have been 
spending the weekend with my bride, our granddaughters and their
Mom and Dad and things don’t get much nicer than that.

Senior Engineer –
Facility Dynamics Engineering
here for an index to previous posts

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