Tiny Might skimmer rockin'
- Thread starter smjtkj
- Start date
BeanAnimal
Premium Member
Yeah... 6" pvc, so it will be a bit bigger than 6" (tuff luck finding the right salad bowl huh!).
What I want to do is put a flange where you glued your seam. The bottom half will be PVC and the top Acrylic. The top half will attache to a 4" neck just like yours (if spazz has time to do one up cheap) Otherwise I am concidering using rare earth magnets to hold the cup on.
Sorry to hijack.. I guess I should get off my butt and start my own thread.
What I want to do is put a flange where you glued your seam. The bottom half will be PVC and the top Acrylic. The top half will attache to a 4" neck just like yours (if spazz has time to do one up cheap) Otherwise I am concidering using rare earth magnets to hold the cup on.
Sorry to hijack.. I guess I should get off my butt and start my own thread.
spazz
New member
smjtkj those are some nice pics. it seams to be breaking in now so your getting better production. that and its taking more air into the pump. now that you dropped the wattage about 8 watts is the motor runing cooler? that could make the difference right there. you dont need much to lower the temp of the motor 20 deg. i was messing around with my pump and broke the needle wheel. so i have to make another one. i will get a couple more blanks for you to play with. i just need your address again. i did open up the votive on the pump housing. i cant believe how much extra plastic you can remove from the housing and still not hurt it. the wattage dropped 8 watts just opening up the housing. so now im down to 71 watts also. but i feel we can do better with it. i did run the motor with out any wheel on it and it runs at 45 watts. thats with zero restriction on the motor. so it is taking about 26 watts to spin the needle wheel around with water and air inside. thats not too bad. as far as heat sinks go i was wondering why we couldnt take an extruded heat sink and mill the bottom super thin so it can be wraped around the motor and held in place with hose clamps. when aluminum is super thin it is very flexable.
BeanAnimal
Premium Member
My 7' skimmer progress
There ya go.
I may have to build a mold for my neck then. What thickness of acrylic did you use?
There ya go.
I may have to build a mold for my neck then. What thickness of acrylic did you use?
Spazz, the motor is noticably cooler to the touch. It is still really warm but I can keep my hand on there and burn my skin. I think the milling of the heat sinks is a great idea and would do the trick. We can buy them cheap too! The blank wheels can be cut for .040 and .050. I found both of the sizes. I will probably try the smaller first. If it works, we will not need the .050. If you want to wait to send the .050 that's fine. I am thinking the .040 is gonna work.
BeanAnimal
Premium Member
I am starting to wonder of porting the OR3700 will have any benefit. I have not looked at it to hard, but I fear there really isn't much plastic to work with.
I suppose I could jump on board and switch it out for a TM pump. How quiet is the thing?
I suppose I could jump on board and switch it out for a TM pump. How quiet is the thing?
It is really quiet, but it may be way too much for the smaller body.
Probably like the other more quiet external aquarium pumps. I have it blowing into a 10 inch bubble chamber and it is comletely full of bubbles. I don't know how much plastic is there either. I did see on the eheim used on the ATI bubblemaster, they did exactly that. Just proceed slowly if you try. Heck you can always reduce the intake with a ball valve! Go for it.
Probably like the other more quiet external aquarium pumps. I have it blowing into a 10 inch bubble chamber and it is comletely full of bubbles. I don't know how much plastic is there either. I did see on the eheim used on the ATI bubblemaster, they did exactly that. Just proceed slowly if you try. Heck you can always reduce the intake with a ball valve! Go for it.
OK!
Dale I could not turn the input water off because the height in the skimmer would drop a couple of inches. The only way I could keep the height was top shut off the gate valve completely on the output. That was too many things at once to do. So these numbers are with the water flowing thru the skimmer.
1. Skimmer diameter is 12" od
2. diffuser plate height is 6 inches
3. water height with air injected is 36.5 in from diffuser plate or
42.5 in from botttom of diffusor chamber.
4. height of water with air off is 33 from diffuser plate and 39 inches from bottom of diffusor chamber.
5. height with air injected is 36.5 in from plate or 42.5 in from bottom of chamber.
6. Time for air cloud to reach top when turned on is 7-8 seconds
7. Time for cloud to reach top when air is turned off is 11-12 seconds
Thanks Dale
tinygiants
New member
The air/water ratio is 9.6%.
The air volume you are getting should be about .86 ft cubed to maintain the 9.6%.
To get the 13% ratio with similiar bubbles (assumes the same rise rate as current bubbles) would take 1.17 ft cubed.
Your bubble rise rate seems to be 3.32 in/sec - 3.04 in/sec.
Dale
The air volume you are getting should be about .86 ft cubed to maintain the 9.6%.
To get the 13% ratio with similiar bubbles (assumes the same rise rate as current bubbles) would take 1.17 ft cubed.
Your bubble rise rate seems to be 3.32 in/sec - 3.04 in/sec.
Dale
BeanAnimal
Premium Member
Dale... weve been through this a bunch of times in your thread. Did you ever finish up the spreadsheet? I did a TON of work to it months ago, but can not seem to find it now. I had worked on updating it for RECIRC skimmers with a feed pump.
In any case with the water flowing through the skimmer, he may actually have a bit more air than that (have not wrapped my head around this yet, so it may not be well thought out).
I assume you are just comparing the water height with and without the air running and assuming that the rise in water height is the displacement volume of the bubbles?
Here is what I am not getting... over 13% will just lower the water line in the skimmer as the bubbles rise out and no longer displace said water. That is easy enough to see. So the foam would be dryer on top, but a shorter neck would negate that problem.... very counter intuative.
What I am getting at is that I am not quite sure we are looking at Esobals number the right way
In any case with the water flowing through the skimmer, he may actually have a bit more air than that (have not wrapped my head around this yet, so it may not be well thought out).
I assume you are just comparing the water height with and without the air running and assuming that the rise in water height is the displacement volume of the bubbles?
Here is what I am not getting... over 13% will just lower the water line in the skimmer as the bubbles rise out and no longer displace said water. That is easy enough to see. So the foam would be dryer on top, but a shorter neck would negate that problem.... very counter intuative.
What I am getting at is that I am not quite sure we are looking at Esobals number the right way
tinygiants
New member
Height of the skimmer has no effect on the ratio. The reason is rise rate.
For example: A feed rate 1cfm results in 10% ratio for 2 ft skimmer.
It would still be a 10% ratio in a 1 ft skimmer or a 4 ft skimmer.
I verified this with testing in my skimmer by raising and lowering my water level.
A given volume of air will stay suspended in water based on the speed of the bubble. In order to get a denser ratio, you have to increase the quantity of bubbles or increase the dwell time.
dale
For example: A feed rate 1cfm results in 10% ratio for 2 ft skimmer.
It would still be a 10% ratio in a 1 ft skimmer or a 4 ft skimmer.
I verified this with testing in my skimmer by raising and lowering my water level.
A given volume of air will stay suspended in water based on the speed of the bubble. In order to get a denser ratio, you have to increase the quantity of bubbles or increase the dwell time.
dale
BeanAnimal
Premium Member
Maybe we should open another thread on this... as I hate to polute this thread with a tangent conversation.
I tend to agree with you... but would like to delve into this a bit further.
I tend to agree with you... but would like to delve into this a bit further.
tinygiants
New member
One thing to remember is this ratio should be taken from the water line and the wet just created bubbles after the skimmer stabilizes. Measuring all the way to the collection cup gains nothing.
In a hartford loop set up, the water level does not drop as the air is injected. The air saturated water will be higher than the loop side. This is due to density. The hartford loop is filled with water. It takes a taller head of air water mix to equalize with the denser water through the hartford loop.
Dale
In a hartford loop set up, the water level does not drop as the air is injected. The air saturated water will be higher than the loop side. This is due to density. The hartford loop is filled with water. It takes a taller head of air water mix to equalize with the denser water through the hartford loop.
Dale
BeanAnimal
Premium Member
Yes, as that would appear to by just supported foam and not part of the saturation.
BeanAnimal
Premium Member
In any case we will soon have another tall skimmer to do some calculations with. I just need to get the damn air pump and that may take me a week or so.
hahnmeister
In Memoriam
Bean, and anyone else looking for acrylic domes/domes with flanges. You can get them here...
http://www.calplastics.com/custom/stockhemi.html
Or here...
http://www.acrylicdomes.net/acrylicdomes.htm
The cool thing is that you can get them with the flange ring as part of the dome so you can easily tap it for screws, or route it for a twist lock flange.
I still question the use of a dome as a reducer neck though. Remember that old physics/geometry problem where there is a marble on a ledge, and the marble can take one of three tracks to get to the bottom, but one is faster than the others... the choices include a diagonal line from point a to point b, and two cycloids (1/4 circles), in the two possible orientations? The marble will fall the fastest on the cycloid that starts with the steep incline and then less before point b. Using a dome as a riser neck is a bit like that. Granted, these are bubbles and dont accelerate the same if anything at this point, but the idea behind most reducers is to both slow the ascent of the bubble, and maintain its velocity as much as possible in the upwards direction. A dome collection neck doesnt slow the rise of the bubbles, and then adds a horizontal motion at the top, angling the bubbles so that they exit sideways at the top, which is really adding alot of turbulence to this area of the skimmer that should be as calm as possible. This is why you really want to have a curved funnel/trumpet shape, not a dome. I would go so far as to say that a regular flat flange as a reducer would work just as well as a dome top. The added horizontal vector from the dome isnt what we want here... is it? Think about a kid on a waterslide...the kind where it starts with a great drop, then angles upward at the end so that the kid flies across the water surface a few feet (rather than plunge into the water straight down). Thats whats going on with the bubbles here, only the 'kids' are rising, and the slide is upside-down...
http://www.calplastics.com/custom/stockhemi.html
Or here...
http://www.acrylicdomes.net/acrylicdomes.htm
The cool thing is that you can get them with the flange ring as part of the dome so you can easily tap it for screws, or route it for a twist lock flange.
I still question the use of a dome as a reducer neck though. Remember that old physics/geometry problem where there is a marble on a ledge, and the marble can take one of three tracks to get to the bottom, but one is faster than the others... the choices include a diagonal line from point a to point b, and two cycloids (1/4 circles), in the two possible orientations? The marble will fall the fastest on the cycloid that starts with the steep incline and then less before point b. Using a dome as a riser neck is a bit like that. Granted, these are bubbles and dont accelerate the same if anything at this point, but the idea behind most reducers is to both slow the ascent of the bubble, and maintain its velocity as much as possible in the upwards direction. A dome collection neck doesnt slow the rise of the bubbles, and then adds a horizontal motion at the top, angling the bubbles so that they exit sideways at the top, which is really adding alot of turbulence to this area of the skimmer that should be as calm as possible. This is why you really want to have a curved funnel/trumpet shape, not a dome. I would go so far as to say that a regular flat flange as a reducer would work just as well as a dome top. The added horizontal vector from the dome isnt what we want here... is it? Think about a kid on a waterslide...the kind where it starts with a great drop, then angles upward at the end so that the kid flies across the water surface a few feet (rather than plunge into the water straight down). Thats whats going on with the bubbles here, only the 'kids' are rising, and the slide is upside-down...
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