Compressed air leakage

You may refer to the tip sheet "Minimize Compressed Air Leaks" here: (I am just too lazy to dig up the equation for you )

http://www1.eere.energy.gov/industry/bestpractices/tip_sheets_compressed_air.html

and you may find this sourcebook beneficial too:

http://www1.eere.energy.gov/industry/bestpractices/techpubs_compressed_air.html

Don't bother, it's quicker to plug the hole.
Del

This is the best answer that only an engineer can give, How much leaking is for scientist (for writing a paper after modelling that too for a publication purpose).

I have seen these papers in my graduate and undergrad days- where everybody used to boast about no of papers published in IEEE journals.

If it is a tapping point i can understand the distribution pattern for sharing esp in hydraliuc lines branching.

(who has drilled the hole and why ?)

One of the best answers ever seen and deserves a GA.

If you really want the answer of the problem the following are required

a) dia of the pipeline and its surface roughness (inside)

b) distance from pump

c) distance from the sink (end point)

e) Back pressure offerred by sink.

f) CFM consumed by the sink

d) CFM capacity of the compressor

e) shape of the hole for accurate calculations deburr the hole edges inside and outside.

With all the above and a few other data it may be easy to calculate the orifice restriction to air (the data about the hydrodyn props of air are available) just draw a diagram (being electrical i like to draw it like electrical diagram) , put the individual resistances as electrical R, , Pressure = V and flow is I

the answer is ready. Like del, too lazy (and too old) to do the class homework.

Does this help?

Calculating Air Leakages: by Ducon

Leaks are significant source of waste energy 20 to 30% of a compressor's output.

Leaks create pressure drops, increasing processing & operation time, shortens life of almost all system equipments. They must be immediately detected and repaired.

Leakage rates for different pressures and equivalent orifice sizes can also be obtained from literature as:

Based on Compressed Air Audit of detected Leakages at 100 psi

1/32" x 15 = 1.6 x 15 = 24.0 Cfm/6 = 4.0 Kw x 24 hrs = 96 .0 KW 1/16" x 35 = 6.5 x 5 = 32.5 Cfm/6 = 5.41 Kw x 24 hrs = 130.0 KW

Total: = 226.0 KW x Rs.5.0 /KW x 30 Days/Month. = Rs.33,900/Month Lost

Work out the orifice size in imperial units of 4mm . Cross reference that with 90 psi (6 Bar approx.) = CFM lost/6 = Kw x hrs/day = Kw/day x 30 days x Rate/Kw = Loss/Month from 4mm hole. Easy Now.

Thank U, Ducon.

May I have the same table for the orifice dia from 0.5" to 2.5".

Regards,

Sanjib

I dunno where to get them. In compressed air a 1/4" leakage is TOO MUCH. All the hissing n pissing cannot be avoided. Suggest you add 1/4" + 1/4" = 1/2" and make your own factor from 1/2" to 2" for CFM lost at corresponding pressure.

Flow Q = AVK ,

K = const (for straight drill = 0.62) ;

A = Cross-section Area ,

V = Velocity of Air = √(2gH) , H = Head

H = (P / ρg) , ρ – density, P = pressure

V = √(2gP/ρg) = √(2P/ρ)

Q = πr² K√(2P/ρ)

= C r² √(P/ρ)

where C = πK√2 = 2.76 r, P in SI units

= πK√2/(1000²) √98066.5 = 0.000863 r in mm, P in kg./cm2

find the density of air in that temp and pressure and you know the volume of air leaked m3/ sec

(This is assuming the header as sufficiently unaffected by the leakage, otherwise approximate)

Also you can see the flow rate is directly proportional to r ² so if you us Ducon chart , you can find at any pressure and dsiameter you want, if you know.

Had to look through my hydraulic (hopefully my formulae are correct else somebody can modify )

caution: Never used them and checked, we always use adjustible orifices on our hyd line and adjust practically on the fluid and other parameters , so if you lose more air, CR4 is not responsible ()

Sanjib

I make it about 21 scfm, rather less than the figure from #4, which according to my calcs is worst case and assumes orifice discharge coefficient = 1.

But Del's advice is best by far - don't calculate it, fix it!

Cheers......Codey