Best method for generating suction

[dmehling]

I am working on a design for a page turner, and I want to use suction as the means for turning the pages. I was thinking of using a fan or something attached to some tubing with a suction cup on the end which would pick up the page. What kind of fan should I use? I was thinking that this might work:

http://www.allelectronics.com/cgi-bin/item/CF-270/220300/12_VDC_97_MM_CENTRIFUGAL_BLOWER_.html

Could it provide enough suction power? I have also considered modifying a vacuum cleaner or a dustbuster, but I'm not sure if they would be to powerful.

 

[Danger]

Welcome to PF, Dmehling.
If the one fellow's comment about it blowing more than a hair dryer is accurate, it should be quite more than adequate. I'm a wee bit concerned about what your 'throttling down' the airflow through whatever sort of nozzle you plan to use will have upon the health of the motor. That might not apply, though, because it's not a positive-displacement blower.
Other details of your design can make a big difference to your choice, as well. The duty-cycle is important. Is this thing supposed to run all of the time, and just be applied to the pages as needed, or does it start and run just long enough to turn one page and then shut off? If the latter, how long will it take to 'spool up' to an operational vacuum level? How compact and/or portable must it be?
If you need instant on-demand availability, it might be worth your while to use a vacuum accumulator with an intermittently operating pump (like a 'negative' air compressor and tank).

 

[dmehling]

How would I determine whether I am wearing out the motor on a fan? I would probably have tubing between 1/4 inch and 1/8 inches in diameter, connected to a suction cup of perhaps 3/4 or 1 inch.

I think it would be important to have instant availability of suction power, but I'm thinking that I would run the fan continuously, which would probably be two hours at a time. Would I need a vacuum accumulator in that case?

I have done more extensive research on different fans I could use, and an important measurement for determining which one to get is based on the necessary static pressure I need to generate. The only problem is that I'm not sure how much static pressure is required to lift a page. I would appreciate it if someone could give me some examples of how much lift or suction power would correspond with a given measure of static pressure. For example, how much static pressure would be required to pick up a pencil, a piece of cardboard, a baseball, or any other common object?

 

[Danger]

How would I determine whether I am wearing out the motor on a fan?

I suppose that there's some way to measure the resistance while it's operating, which might give an indication. More to the point, though, is a simple temperature check; if it isn't overheating, it's okay. I'm thinking of the situation that arises when a vacuum cleaner is run when clogged, or a furnace filter doesn't get replaced. As I said, it probably isn't going to be a problem in this case. Since that one dude is using it for computer cooling, it must be rated for continuous use (as one would expect a fan to be).
I just thought of an easy way to avoid this even if it does initially seem to be a problem. You could have a port that's open to atmosphere when the suction isn't being used, so as to provide unrestricted airflow through the unit. Activating the nozzle would bypass the port for a couple of seconds. That is, of course, a complication that should be unnecessary; I'm just trying to cover all of the bases.

I would probably have tubing between 1/4 inch and 1/8 inches in diameter,

This isn't exactly one of my main areas, so I'm just going by experience; I wouldn't go below 3/32" inside diameter. That's just based upon flow restriction. Consider the difference that you feel when drinking a pop through a skinny straw as opposed to a fat one. The smaller it is, the more strain will be placed upon the motor. Of course, too large would make it difficult to establish a vacuum, and you have to consider how convenient the thing is to use. If it's mechanised, the lightness and flexibility aren't as important as they would be if it's hand-held. The suction cup area that you propose seems appropriate to me.

I think it would be important to have instant availability of suction power, but I'm thinking that I would run the fan continuously, which would probably be two hours at a time. Would I need a vacuum accumulator in that case?

No. That would only be if you need the vacuum on demand, but can't run the pump continuously.

an important measurement for determining which one to get is based on the necessary static pressure I need to generate. The only problem is that I'm not sure how much static pressure is required to lift a page... ...how much static pressure would be required to pick up a pencil, a piece of cardboard, a baseball, or any other common object?

I'm afraid that this is way out of my league. I've turned pages with one of the aforementioned drinking straws (when my hands were dirty), but I have no idea of how that correlates with static pressure. Do keep in mind that there are a couple of complications that don't directly depend upon this. One is the porousity of the paper; glossy is a lot easier to get a vacuum lock on than something like a cheap newspaper. There's also the size of the page involved, which equates to its reluctance to move. Even more common, in my experience, is the electrostatic charge on glossy paper that tends to make the pages stick together. Last, but not least, is the chance that someone spilled something or squashed a bug on a page, which pretty effectively glues them together. I believe that the static problem can be overcome by sliding one page over the next while lifting, but I have no idea of how to deal with bugs.

edit: Okay, I know that there are dozens of Mentors and Science Advisors reading this and giggling in their beards. How about one of you get in here and help me out?