Is there a pump that can deliver low pressure and good flow rates?

A good high power vacuum cleaner pump would provide almost that much vacuum and air flow... errrrm 30 cfm .... not sure how many litres a min that is

Maybe 1000 litres / min ? hmmmmmm that's a lot!

Okay you might have to use multiple vacuum cleaner motors to get that flow rate!!

Electroman,

Thank you for the feedback. We originally tried using an industrial vacuum pump. Not enough suction. Then we joined 2 pumps in parrellel brought the pressure down more, but not enough and not enough flow rate. Unfortunately, I don't think that I am going to get there via the inexpensive route.

If you have any other thoughts please pass them along.

Happy Holidays.

What size is your prototype? how do you desire to connect it to the pump? will liquid affect your prototype or particles entrained in the airflow?

What size is your prototype?

A tube roughly 11"diameter x 12"long. I need to draw the air through this tube inside the tube is a labyrinth of chambers. I understand that this will create a certain amount of resistance to air flow and make the pump work harder. But the air can move freely from entrance to exit port, and this is a fairly small distance that the air needs to travel from front to back. There will be roughly 10 inlet ports with valves that allow me to adjust the diameter of the port from 1/2" down to fully closed. There are also 10 exit ports with similar valves to adjust the diameters from 1/2" down to fully closed. This will allow me to manually adjust airflow based upon the number of ports open and the diameter or each port.

How do you desire to connect it to the pump?

I will connect the pump through short hoses directly to the 10 exit ports. If that did not work then I could fabricate a plate that connected the 10 exit ports to the intake of the pump.

Will liquid affect your prototype or particles entrained in the airflow?

I have already taken into account the removal of liquid and solid particles. So yes, both substances will effect my prototype but not negatively.

I look forward to your reply.

So far you have described a tube 11" dia. x 12" long closed off one each end and each end has 10 ea. 1/2" dia. valved ports. Inside is some sort of labyrinth or is it 10 labyrinths? Total inlet port areas are 10 x 0.397 = 3.97 sq,in. vs. 8.6394 sq.in. total area.

If there are 10 discrete labyrinths, then simply run the flow test on each labyrinth individually. If you must test the entire assembly then a turbine fan or a wind tunnel might possible fill the bill.

See a new General Topic "Why....................?

Sterling Stan,

Thanks for you comments. The 10 entry ports connect to 1 common chamber that twists and turns like a labyrinth, but all the entry and exit ports tie into this common internal chamber. The point in mentioning this was that air will not flow directly from entry to exit.

I am not a fluid expert nor an aeronautics person, but my understanding of air/fluid flows is that they would rather avoid high pressure areas. So I would assume that if I put this device in a wind tunnel that the air would flow around it rather than through it. Further I am not sure how the wind tunnel would deliver a pressure drop?

Thanks for the comments.

AE:

After thinking this over the flow rate(s) and pressure drop(s) may not be compatible with the specified tube.

I would suggest some flow rate calculations based on using an orifice plate instead of the tube. Lots cheaper than equipments and tests. It's been too long since doing this calculation. Perhaps someone more adept can help.

The wind tunnel could be choked off to just the tube. The turbine fans are high volume and high flow rate.

http://vacuum-pumps.globalspec.com/SpecSearch/Suppliers?QID=8437031&Comp=1330

These sorts of things are often used for pulling down vacuum fixtures for ICT (In Circuit Test). I worked with one electronics manufacturer that used a vacuum pump designed for milking cows.

Randall,

Thanks for the comments. I have already spent some time using the Global Spec search engine evaluating the vacuum pumps listed on their site. I could find a few pumps that drew the pressure down, but nothing could deliver the flow rate needed.

Just a thought AE.... We designed a medical negative pressure chamber 15 years ago for medical research...

The vacuum pump was very critical as it had to pull a vacuum (not as much a 7 psi) even with a doctors' hand inserted through a handling hatch, also the pressure had to be cycled at up to twice a second from predetermined set points...

i.e. upper pressure -30 millibars lower pressure -60 millibars (almost -1 psi) gauge pressure, the volume of the chamber was up to 2 m^3 and the pump we used managed to change the pressure within 0.1 second...

It was a swine to keep quiet though... John.

Electroman,

Thanks for your example. Sounds like an interesting project. If you remember the type of vacuum pump or the manufacturer then I could see if they have a device that would meet my needs. I too have heard that these pumps make an aweful racket or high pitched whine. Thank you for your comments.

I assume that you want to move air. A good rotary screw compressor will pull those vacuums and move sufficient volume. The best screws for the job are those used in the natural gas production industry. There are several brands which will do very well, LeROI, Quincy and SullAir among them. They typically do not sell to end users, so you will need to see a distributor or gas packager to get one. You want a small one, about 80mm rotor diameter. It will use about 5 - 10 hp and produce between 20 and 50 scfm at 15 inches mercury vacuum and 30 to 50 psig discharge pressure at sea level. A properly designed screw compressor package will easily handle those conditions trouble free for very extended periods. Again, gas packagers in the natural gas production business are the most experienced at these conditions.

JohnB,

This was a very helpful reply. I was hoping that someone familar with a similar problem in another industry would reply. I will use the web to find some manufacturers reps that deal with natural gas production cos. Do you think that Air Products and Chemicals would have similar pumps since their products are also bottled gases?

I look forward to investigating your leads. Thank you again for replying to this question.

I apologize for not responding sooner. For some reason, I am not receiving additional posts to this thread. If you search on "gas compressor packager" on the web, you will find a number of companies which may be able to help you. Many of those companies are customers of ours with whom I have direct contact.

Meric Balaban also has some information which looks useful. The rotary screw units he has provided links to may be the best technology because of the clean, dry air requirement. Blowers may not get to the vacuum levels you need at the flow rates you need. However, the manufacturers will be able to get you the best information.

Try a similar to a circulation pump in a Power Station (i.e. low head and high flow)

Are you referring to a circulation pump that circulates water? I am only moving air with my device no need for moving liquid fluids. I am unfamilar with circulation pumps at power stations that circulate air. Maybe you could provide a little more information for me.

Thanks for your comments.

I am working in a chocolate company and using great deal of vacuum for product transfers and handling. We are using several ways of vacuum generation depending on the task required.

I may say that you do not need anything of the sort used in power stations for your flow rates and level of vac. is far below the range of those pumps used in power stations.

Assuming you have access to a compressed air supply, I suggest you to use vacum generators which create vacuum using compressed air by venturi principle. These devices are very small, low cost, compact (not larger then a pack of cigarette), easy to install and easy to regulate (just by regulating the compressed air supply pressure you can regulate the vacuum flow rate). There is no motor or moving part involved, it will consume compressed air to create vacuum. My guess is that in your specific case normal compressed air consumption will be at a rate of twice the amount of normal vacuum flow rate needed. The only problem with these devices are that they are not very energy eficient and not good for high volume flow rates. Lucky, you will use it for testing only, energy efficiency is not your concern at all, besides your flow rate falls within their working range. If what you need is something to do the job at the lowest investment. I suggest you to go to the link www.piab.com Piab(Sweeden) is one of the leading suppliers of such vacuum generators with many varieties and I am using them since quite some time. For more suppliers I may suggest companies like FESTO(Germany) , SMC(Japan) or run a search in google for the entry "vacuum generators". I do not know where are you from but all 3 companies given above are established in many countries.

I would like to give some hints for the test rig.

Although I am not fully aware of the design and conditions, I understand that you basicly have a closed tube with 10x1/2" intake valves on one end while there are 10x1/2" exhaust valves on the other. In between there are some restrictions which looks like labyrinths. In order to be able to create vacuum inside the tube you need to create a pressure drop across the tube. Assuming that your labyrints will not provide the necessary pressure drop needed then it can only be achived by having larger area on the exhaust valves than the intakes valves. Therefore while doing the test connect the vacuum generator to the fully open unrestricted exhaust valves and keep the distance from exhaust ports to the vac. gen. as low as possible. It will be best to use a manifold plate with large passages for air. I do not suggest you to use hoses. If you insist in using hoses then use oversized hoses and keep them as short as possible and make sure connections do not leak.

Once u set up everything run the vacuum generator by supplying air and start with fully open intake valves then gradualy trottle the intake valves to adjust the level of vacuum inside the tube. Warning:You must be sure that tube will not collapse when vacuum is applied. Those compressed air powered vacuum generators can reach quite deep vacuum if you totaly close the intake valves. I presume you will connect a vacume gauge somewhere on the tube shell. (Actualy if you connect 2 gauges , one before the labyrints and one after them then you can measure the pressure drop thru them too). I do not know why you are doing all these anyway.

If also the volume flow rate thru the tube must be a definite value together with the vacuum level inside the tube then you have to trottle the intake valves and compressed air supply to the vacuum generator simultaneously to reach the desired values. This shall not be very easy but doable. All you need is to develop a skill by trial and error.

Since you do not have any flow data with regard to the tube in hand; I suggest you to choose a over sized vacuum generator for it is very easy to regulate it by just regulating the compressed air supply to that.

Mericbalaban,

Very interesting reply. I was totaly unaware of this technology. I have briefly looked at the PIAb site and am encouraged by what I saw. I will investigate this in more detail in the next few days. I fully understand your comments and words of advice (no tubes or short tubes, outlet diameters larger than inlet dia., etc..) I was planning on a prototype that relied on electricity as its input power source, but I guess I could rework some parts and use compressed air as the power source. I think that using this trade off will allow me to really reduce the weight and size of the components needed to fully operate the device. Before any Guru's jump in and point out the obvious, I understand that the compressor is drawing its power from electricity.

This posting has proven to be very helpful. I have not used this site to assist me in my prototype development before, but I see a lot of value in getting input from this broad range of perspectives. I have always believed in diversity of thought and this confirms my instincts.

Thank you again for your thoughtful and spot on reply. I am cautiosly optimistic.

AE,

Thank you for your very kind comments on my post.

After writing the post I have checked thru the companies that I had suggested you. To my surprise I`ve noticed that only PIAB has one Vac. Generator which will provide the necessary pressures and flow rates you need with a single unit.

Right here, I would like to mention one point to you that these compressed air powered vac. generators can be connected in parallel very easy. If you are using multiple units of the same design then just connect them to the same compressed air source and start and regulate all together then the flow rates will simply add and vacuum reached will be same as what you reach with a single unit.

I also want to warn you again in something that these devices may prove to be terrible in some cases when it comes to overall energy eficiency. I try to awoid them by chosing electrodriven mech. pumps in some situations. But in some special cases they become the best chose and I use them. What I can say that I use them when I need a relatively low vacuum at a relatively small flowrate. Higher the flow rate and smaller the amount of vacuum needed then a radial vac. pump may be much more efficient.

I wish you good luck and success with what ever you are doing.

Tom,

A I looked closer into the vacuum generators that you recommended I saw that only one was going to meet my needs and yes it was from PIAB. I did not thoroughly read the technical description of how the device works, but from what I saw there may be a problem. It looks like the vacuum air stream is combined with the compressed air stream upon exit from the device. That won't work for me. Once I have processed the air through my device I don't want to mix it with a new unprocessed air stream. Please let me know if the two air streams will be combined upon exiting the PIAB device.

As far as business opportunities, I am an early stage start up. When we are ready to expand into Africa I would be happy to recontact you.

I hope that you have a happy New Years.

Regards,

Chris

Chris

Sorry for the mistake on my second reply where I posted it as Guest and caused some misunderstanding. Anyway I'm not from Africa.

If you need isolated flow then sorry to say that you have to forget the compressed air powered vac-generation. The swept air from the tube will mix with the compressed air inside the Piab and will be exhausted from Piab as a mixture. There is no way of keeping them seperate.

Developing this discussion I realise that you will somehow process this air thru the tube and do not want to mix it with anything else probably not even with oil. In this case may I suggest you to check: http://www.aerzenusa.com/vacuums.html where you may find various electric motor driven pump solutions. This is a german manufactureer who manufacture both dry running rotary lobe type and dry rotary screw type vacuum pumps. Original webpage of the company is http://www.aerzener.de/publicity/xenario/internet_d.nsf/index/en.htm . Only problem I can think of is that even their smallest models may be too large for you in terms of flow rates. Besides most of these pumps are god damn noisy, they need to be housed in a acousticly isolated cubicle of some sort.

rgds

Meric Balaban

Meric,

Sorry for confusing you with the other guest commentor to my posting. I appreciate your comments and will be investigating them now that the holidays are over and my in-laws have left the building!

I am pretty bummed out about that PIAB device that really looked great until the combined streams issues surfaced. I guess that I should have figured that out before I read all of the other info on their website. It is pretty obvious that would be the only way that it could work. Thanks for the comments I am now getting back into the swing of things. Happy New Years.

yeah actually am a busines man am a contractor my company work on oil and gas industries.My company name are Feu technical international limited.

176 Grace bill road eket akwa ibom state nigeria.

We are looking for company to represent in nigeria,if these could be of any business to you please let us to know.

Cheers

Tom.

Propably you should check"Ogden" or "Pressure Powered Pump" manufactured by all renowned leading Manufacturers like: Spirax Sarco, Armstrong, Johnson Corporation, Yarway, Gestra, ITT Domestic, Watson McDaniel, Bestobell, TLV, Clark Reliance, Spence & Nicholson, Dunham Bush etc.

These pumps are positive displacement type and operate with either steam/compressed air with capacities ranging over 7000 kg/hr. They are ideal for drainling liquids/condensate under "Vacuum".

These are simple pumps with inlet/outlet check valves 1" thru 3" .There is a 1/2" connection for motive steam/air upto 8.5 bar and a 1" connection for exhaust.

In Vacuum application the exhaust is connected to the vacuum unit being drained to break the vacuum allowing the fluid to be pumped to enter the pump body. There is retrofit float assembly which allows motive steam/air to enter as the fluid level in the pump body rises. The moment the float goes down & fluid is pumped out, the motive inlet valve closes and opens the exhaust 1" .

This is widely used to drain multiple-effect evaporators and all vacuum application units.

The capacity is then determined based on the lift head & backpressure. You can use even 2 or 3 pumps with a Receiver/ Packaged Units.

Check these out at all manufacturer's sites.

Other than Ogden/ Pressure Powered Pump you can use Jet Vacuum Pumps.

These are like Thermocompressors/ Ejectors. There is a venturi tube with motive high pressure steam to extract. This then depends how you apply the system:

If you want to extract 0 psi steam fumes(say from Bleaching/Steam exhaust) this becomes a Thermocompressor. Invert these and it becomes an Ejector (used in Vegetable Oil & Soap Mills) to create vacuum. Use this in your application it becomes Ejector Pumps/ Jet Vacuum Pumps.

Check up GEA Germany/Croyll Reyons site (Reyons ok but not sure of the first name spelling) or simply go to Google & TYPE " Jet Vacuum Pumps / Ejector Pumps"

Ducon,

Thank you for the reply. I am not familar with Jet Vacuum pumps. I will investigate the suggestion on both of your emails.

Happy New Year.

Txs and happy new year to you too.

Yesterday i downloaded from Forbes Marshall's (Spirax Marshall India) on this subject. They call it Thermocompressor . Suggest you look this up.

Rgds

Try a liquid ring vacuum pump. Google for this. There are 15 or so manufacturers. Unfortunately they will be VERY expensive in this size.

Thank you for your comment. I will look into liquid ring vacuum pumps, but I don't like the sound of VERY expensive. Happy New Years.

use positive displacement vacuum pump

Hi AE,

I have gone through your post and other's feedback, i would like to suggest you about DSRP vacuum Pump, its best suitable for you requirement, Check rotary pistonj vacuum pump in google.

Bali