I make that about 77.5L per chamber per day, thats a fair amount of waste for 32sq ft. To put it into context, thats the same amount of water 32 full grown tomato plants would use if they were in full sun for 17 hours. Commercial enterprises focus on efficiency and productivity, for horticulture that equates to maximum crop weight in the shortest time using the minimum amount of resources. With AA nozzles you could maintain a constant (excessive) level of mist in the chamber with 13L per day.
Tefen Nozzles @ 100 PSI for Aeroponics
- Thread starter indrhrvest
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indrhrvest
New Member
Less water I agree, but the use of compressed air is pretty ineficient. The question would be, is more water usage cheaper than more eletricty? City water is only around $0.005 per gallon. With an AA setup, you'll need more piping, a compresor and more components to maintain. That's a higher initial investment cost and posibly a higher on going cost.
I do plan on testing an AA setup, that's why I have the compressor, but on paper it seems like the cost to run the compressor outwieghs any other advantage.
I looked up Tefen's nozzle chart, the one on the retail site was not correct.. it's .066 Lit/Min @ BAR 6. That's 356.4 Liters per hour for the entire system (64sq feet).
Let's be optimsitic and say I can do 2 seconds on, 4 minutes off. That's going to be 3,207 Liters every 45 days. Figure 20% run off, that's 3,848 liters, or 1,016 gallons every 45 days.
In real dollar terms, that's just $5.08 worth of city water and still a far better consumption rate over conventional farming.
You`d have less components to maintain, 4 AA nozzles versus 90 hydraulic nozzles to cover the same volume. No rigid manifold in the chamber (less pipework) and easy access to the nozzles from outside the chamber.
Assuming you use pressure fed AA, the air and water lines would be cheap as they`d only be running at 40psi. If they were syphon fed you could run a single 3/8" air line.
Acheiving the theoretical flowrate of a 2 second pulse is unlikely due to the delay in bringing all the nozzles online and the subsequent run-on from the manifold after it switches off. In terms of liquid entering the chamber with each misting, i think 4 seconds is optimistic. It could turn out to be higher given very few hydraulic nozzles match the flowrates stated on the specsheet.
After you get done with testing AA in your chambers you could have quite few surplus pumps and a helluva lot of surplus hydraulic nozzles in your aero spares box
Assuming you use pressure fed AA, the air and water lines would be cheap as they`d only be running at 40psi. If they were syphon fed you could run a single 3/8" air line.
Acheiving the theoretical flowrate of a 2 second pulse is unlikely due to the delay in bringing all the nozzles online and the subsequent run-on from the manifold after it switches off. In terms of liquid entering the chamber with each misting, i think 4 seconds is optimistic. It could turn out to be higher given very few hydraulic nozzles match the flowrates stated on the specsheet.
After you get done with testing AA in your chambers you could have quite few surplus pumps and a helluva lot of surplus hydraulic nozzles in your aero spares box
indrhrvest
New Member
Well I do have a 2HP Medical Air Compressor and an assortment of nozzles Hart Enviormental provided me to test. I intend to R&D AA nozzles, but the hydraulic route seemed the easiest to pursue first. It's also the most complicated in terms of plumbing. Adding in a AA nozzle is as simple as drilling a hole, and using a grommet..
I can't try them all at once
My only concern with AA is that the amount of air needed in a commercial application would require a very expensive compressor that would not be cheap to operate..
As for the hydraulic manifold, I'm probably going to go with 1/2 stainless square tube fabricated into a frame with stainless 1/8 X 1/8 pushlock tees welded to it. That will solve some of the problems with the higher volume 1/2 PVC pipe.
Can you elaborate on why the coverage of the AA nozzles are better than the hydraulic? Thanks.
indrhrvest
New Member
I think he is basically saying the AA nozzles despense more volume which is true. However at 1 cubic foot of air per minute for most AA nozzles, a large commercial facility would need a 25+HP Rotary compressor running 24/7.. which would be a bit of a drag on the light bill.
The little Shurflo pumps can push those hydraulic nozzles with very little eletricity used.
I will be conducting some tests however to get the data I need to determine the best methods.
Here`s a 2 second pulse from a single pressure fed AA nozzle with 20psi water and 36psi air. For scale, the table seating is 9ft across at the widest point.
http://www.datafilehost.com/download-1f846c8b.html
Thank you both for the information. I'm still having a hard time understanding how there would be a 4 to 90 ratio of nozzles. In the previous posts, the indication was that the AA nozzles would conserve solution making me think that they would put out less volume than the hydraulic. I'm assuming both types of nozzles put out the same size droplets, so is it the velocity (and therefore the distance) the mist is being projected that makes the AA more efficient?
Mike Young
Well-Known Member
Nice hex table! I built me one just like it a couple of years ago. Perfect for backyard bbqs. Sorry, on with the show.
indrhrvest
New Member
Getting the nutrient system fabricated right now.. Still waiting on the roto-molding company to finish my 12" deep Aero chambers and lids. It's sorta been holding me up..
Cheers Mike, i built it 7 years ago, it seats 12 adults and 6 kids or a silly amount of plant pots
KKK, AA`s have an adjustable flowrate and throw mist a lot further than a hydraulic so you dont need as many to get the coverage. You have to shorten the mist pulse timing on hydraulics to lower the combined flowrate. Two pressure fed AA`s could fill an 8x4x1 chamber with mist in 1 second, versus 23 hydraulics running for 4 seconds.
If the nozzles are all 1gph, the AA`s would use 46x less water to acheive the same coverage.
indrhrvest
New Member
I'll be conducting some tests with a lexan sheet over the grow chamber. I also have a water proof Gopro I can use. I've got quite a few nozzles to try out.
I figured I'd do hydraulic first because it required more plumbing. I wanted the system to be modular so the same basic layout would work for a variety of methods. Ultimatley what people use will come down to prefrence. I just want to make sure I have what they want
indrhrvest
New Member
I have to have them because our system is a modular design. I'm going to be growing microgreens with the same system and those AA nozzles aren't going to keep a grow mat moist.
I guess thats based on the ultrasonic nozzles? I have pressure fed AA`s that adjust from 1.8LPH to over 25LPH depending on the liquid and air pressure. They could easily keep a grow mat dripping wet on the higher flowrates Microgreens have very short root systems, a dtw drip feed would be more economical considering most of the mist will fall to the floor.
Microgreens have very short root systems, a dtw drip feed would be more economical considering most of the mist will fall to the floor.indrhrvest
New Member
Some progress pictures. Also have the production molds finished.
