Air Compressors

PWSlack is correct.

Another item to save air is to use Regulators on all circuits and set them as low as possible and still maintain cycle and force integrity.

One other suggeston for regulators is to use one on all cylinder return strokes when the return stroke is at low force.

Any Air Blow Off devices should be replaced with other means or AT LEAST USE A VALVE TO TURN THE BLOW OFF ON ONLY WHEN REQUIRED. Electrically driven Squirel Cage blowers are often used to replace Air Blow Offs.

Well I've done a few of compressed air project long time ago.

1.The first thing first. If you think there is a leakage; you should find and fix it.

2.Check your total outlets capacity(user points). It is most likely that your consumption is more than capacity of your compressors.

3.How you have calculated the capacity of your reservoir tank? Is it big enough to cater for at least a couple hours?

Good answer for items 1 and 2, but I disagree with #3. Given the rate of air consumption, I doubt it would be practical to have a receiver sized for 2 hours air usage at 6 bar. Assuming 100 cfm consumption, the tank would need to be 12,000 cubic feet?

When we did our last air project we found the following site http://www.kaeser.com.au/Online_Services/Toolbox/default.asp#0

Helpful it has calculators for maximum demand, how to size a receiver and how to measure air usage due to leaks, pressure drop and a few others. If you have had to add another compressor your receiver tank is probably now undersized. I would suggest doing an air audit usage of your site, air leakage audit and look at hose sizing eg a 1/2" air drill only needs 3/8 hose not 1/2" hose

Your machines are running "air jets" ?

Many people use these things when they have a problem to solve, but don't realise the following line..

Air is expensive

If they think its not, they use alot of air, and the compressors are running continously.

..he advise to install "headers" to increase the system pressure..

Headers will not increase pressure, but can reduce pressure losses.

..as of the moment the two compressor are continously running and can not reach the cut-off of 6 bar. .

This sounds more like a capacity issue, not a pressure drop issue.

Before doing anything take an inventory of air consumption and see if it balances to air produced. If you don't run 24/7, go in on an off shift, and run the compressors. Any hissing noise will be $$$$$ lost and gone forever! Find the leaks and fix them.

As a rule of thumb, I try to design Compressed Air systems for a 5% pressure drop from the compressor outlet to the farthest point in the plant. For 6 bar, the drop should only be 0.3 bar.

What is the source of this equation? It does appear to be a handy tool.

Does this equation exist in SI units for our friends in other parts of the world? I think they would prefer to use bar, liter/sec, m^3/sec, etc.

I do not know of a metric version nor have I ever needed to do this as 80% of the machinery here is not metric.

I don't see why you couldn't simply use a standard conversion table to get what you need. I'll bet however that someone, somewhere in the world today will post one equal to or better than mine in metric from there side of the world.

From your description and what your technician said it sounds like the T is your problem. I usupect if you measure pressure at the compressor exits ti would be over or close to your 6 bar. Your problem is one compressor is trying to shove its air up the outlet of the other compressor. The harmonics of the gas flow can also slow the opposite compresors airflow by causing a harmonic obstruction in the line.

You also need to ensure the pipes are large enough to handle the required gas flow at 6 bar

Presuming the pipes are correctly sized, your technician is right, using a manifold will fix your problem, that is you need to get rid of the T and join the pipes in a parrallel tapered joint. The joint area between the end of the two inlet pipes and the single (same size) exit (though perhaps you might want to enlarge the exit pipe for better flow?) should be of a length to ensure the joint walls converge at no more than 7 degrees from the centreline to prevent flow loss.

The above will also solve any harmonic interference.

"Presuming the pipes are correctly sized, your technician is right, using a manifold will fix your problem"

You obviously are under the assumption that there are no leaks and the compressors are operating at peak performance or do you know this to be a fact due to personal experience with this particular plant??

Tim,

Actually I'm presuming the Technician and Engineer are both competent and would have fixed all the leaks if there were any. I also relied on the fact that other posters had already dealt with the leaks and high flow devices issue and your excellent earlier post ( thanks for the calculation it will be most useful!) deals with compressor sizing and efficiency issues. That only really leaves harmonics, pipe sizing and backflow compression issues which I think I covered.

When you look at it from that angle, I see what you were getting at. Thanks.

Has the compressor tank been dumped of condensate?

As the tank fills, you'll have less reserve left the more condensate is in the tank.

We have had people here forget to drop the condensate and wonder why the compressor is running flat out with little use.

In this case you can reduce the system pressure below 6 kg/cm^2 and put a booster nearer to the place where high pressure is needed.this may solve your purpose since high pressure will not required in all places

Hey. I have a problem with my air compressor tank. It's not getting filled up properly. Can anyone help me ?

Your joking right?