What am I doing wrong? Or is this to be expected. (video)

[SpaceGrey]

Hi All,

I'm new to the forum.
Getting my separator build going.
Trying to do what I think is a "proper" job measuring CFM losses as I add components to the system.
I got my end filter part build and working with almost no flow loss to my excitement.
Now Top Hat separator attempts so far disappointing, I'm measuring flow with cheap anemometer on 5 inch inlets/outlets:
- Impeller only nothing added: ~7000 ft/min
- Top Hat with 3D printed Parabolic internal outlet: ~ 3500 ft/min
- Top hat with 3D printed straight inlet pipe: below 3000 ft/min

Is this to be expected? 50% flow loss is kind of high IMHO!

This is where link to a Video was supposed to be, but system told me I can't post external links :(

[retired2]

38% for mine.

[SpaceGrey]

38% for mine.

Master, point me to the error of my way!

video:   youtu.be/EaMDVEIaW1k

[SpaceGrey]

This afternoon rebuild it to 11'' tall vs. 6.5 in pictures above.
Gained just a little, now it gets to ~3600 ft/min with parabolic outlet.
(Shrink-wrap and tape are temporary methods of getting it airtight)

[retired2]

Sorry, I don?t have an answer.  It looks like your air straightener has a lot of vanes, but I?m not sure how that could be any worse than my plastic tubes.

What?s the ID of your separator chamber?

[SpaceGrey]

Sorry, I don?t have an answer.  It looks like your air straightener has a lot of vanes, but I?m not sure how that could be any worse than my plastic tubes.

What?s the ID of your separator chamber?

It's 19''
I got those vanes inside to do what plastic tubes does in your system,  figured it's better to get it built in to increase rigidity at the same time.
And in the first picture I measure flow of impeller through that tube and it measured at ~7000 ft/min

[retired2]

The first photo in your most recent group appears to show the inlet wall straight rather than curved.  That could cause turbulence in the circling air stream and contribute to flow losses.  The post below illustrates the point.

http://www.jpthien.com/smf/index.php?topic=563.msg3150#msg3150

[bbain]

I really don't think masking tape and plastic wrap are sufficient to get good enough sealing.  You will have lots of losses without proper sealing.

It also looks like the inlet is too far down in the tophat try rising it a bit and see what effect that has.

[retired2]

I really don't think masking tape and plastic wrap are sufficient to get good enough sealing.  You will have lots of losses without proper sealing.

It also looks like the inlet is too far down in the tophat try rising it a bit and see what effect that has.

The inlet looks to be as high as it can be placed without changing its shape.  Considering single height separators work fine with the inlet flush with the floor, I don?t think the inlet position is the OP?s problem.

[alan m]

The first photo in your most recent group appears to show the inlet wall straight rather than curved.  That could cause turbulence in the circling air stream and contribute to flow losses.  The post below illustrates the point.

http://www.jpthien.com/smf/index.php?topic=563.msg3150#msg3150

i think you could be right. the way that is done means that all the air spinning is effectivly hitting a wall infront of it instead of skipping off of it

[SpaceGrey]

The first photo in your most recent group appears to show the inlet wall straight rather than curved.  That could cause turbulence in the circling air stream and contribute to flow losses.  The post below illustrates the point.

http://www.jpthien.com/smf/index.php?topic=563.msg3150#msg3150

I took that picture before making everything round, it's not straight in reality.
I'm also going to attempt making your tweak from the post mentioned later tonight.

[nucww]

Your last picture is looking in the inlet.  Two possible improvements.
- The bellmouth pipe looks like it is almost to the bottom surface.  If it is, the bottom of this pipe should be about half height or higher.
- The internal ceiling appears to have an opening to allow the bellmouth to be inserted which leaves a big gap between the pipe and the top plate. Airflow may be better if it was plugged or filled.  In addition, this connection needs to be air tight as others had mentioned for all connections.

[retired2]

The first photo in your most recent group appears to show the inlet wall straight rather than curved.  That could cause turbulence in the circling air stream and contribute to flow losses.  The post below illustrates the point.

http://www.jpthien.com/smf/index.php?topic=563.msg3150#msg3150

I took that picture before making everything round, it's not straight in reality.
I'm also going to attempt making your tweak from the post mentioned later tonight.

Don?t expect my minor tweak to make much difference in your performance.  I believe it?s benefit is small at best, maybe not even measurable.

With regard to the comment on the depth of your bellmouth.  I tested mine at several different positions and there was very little difference, but ironically the air flow was best when it was positioned closest to the baffle.  Admittedly, my separator is a single height and it is uncertain what differences that might make.

I have no personal experience with double high builds, but the advice I usually give for the depth of the outlet is to place the flange of the bellmouth level with the bottom of the inlet, or even lower if the height is sufficient.  Since I don?t have a unit it to test, I don?t know if that is good advice or not, but I have not heard anyone report back that it doesn?t work well following that advice.

[SpaceGrey]

Retired2, what do you use for impeller?
I think impeller is a culprit here, mine is "so called 2HP" Harbor Freight.

[retired2]

Retired2, what do you use for impeller?
I think impeller is a culprit here, mine is "so called 2HP" Harbor Freight.

I use the Delta 50-760 dust collector without any modifications, except for a Wynn filter.

You could be right about the HF being the source of your problems.  So many people think the HP rating is a good way to compare blower performance.  It is not!  You need to have the fan curve which shows the relationship of CFM?s and static pressure for a particular blower.  Fan curves are almost never provided for dust collectors and shop vacs.  The reason is simple, manufacturers don?t want you to know how their blower performs under various loads compared to others.