Every time you say whirly bird, I think of this:
3 Likes
You know, my first thought was I didnât change data on copying from one cell range to another. But then it appears that I did it quite correct. Here is the data I was following on. So it either nozzle configuration (internal design) describes flow rates and they can go up or down depending on nozzle\air or this pdf is incorrect. By the way, it has data up to 2.8 bar air pressure per nozzle.
You know, I was going to take ones without that needle at all - its 1/8J body assembly, with just plug. I think it is better to control exact values via pressure regulator, that flow control needle doesnât give any info (to be able to reproduce).
Actually Iâm going to buy a 10-20L used beer keg and use the same air line from an air compressor\air tank but via a different pressure regulator.
Talking about an air tank⌠Do you have used propane tanks around? I can get 50 L used propane tank for around $6-8, and its relatively easy to make DIY air tank out of them: they are rated at 16 bar, so 8-10 bar from air compressor are just nothing for them even if they are old. It is even possible to chain them.
Probably this is the best idea. Itâll come more or less at the same time: from the US and from China. The only though that Iâm also on pretty tight budget yet, so finances might have their own opinion 
No-no, it is totally ok to have the second opinion, it fresh ideas. I totally understand that you have real experience and look very carefully on what have done so far and continue to do. But if there is something new and it is not so hard to try - why not?
2 Likes
Very nice - you found a much newer, current version of the capacity chart! Lets hope it is accurate. The discrepancies are interesting. I wonder if they are related to the âstallingâ that was mentioned in that droplet study you posted earlier? That could explain it.
It sure would have been nice if they also included SMD numbers, but I doubt they tested that. All Delavan is trying to do is burn oil, so they dont really care about that - just the flow rates.
I agree - controlling pressure of the air and liquid is fine for adjusting flow rate and droplet sizes. Plus simpler is better I think as far as potential clogging.
Over all, it looks to me like the lower flow rate options must be producing smaller droplets. That seems to be supported by the study you posted earlier as well. The problem is we dont really have numbers for the SMD. That leaves us with trying to judge SMD based on hang time. It looks to me like the lowest flow rate Delavans will be producing droplets that are on the small side. I think it might be good to start with one of the middle ones - then you can adjust air/liquid pressures until you get in the ball park. I think I would be tempted to start with a -6 or -7. I think the -8 I am using are making droplets just a bit on the large side. Ive decided that its working better to run at closer 6 PSI with the siphon setup Im using.
Those both sound like a great idea to me. You will of course have to be careful flushing the propane tank. Your growth might end up being a little too explosive if not 
The downside to that is you will need solenoids on the water side as well as the air side. I have not been real happy with the cheap ones Ive been using. I have not found any that look better - at a reasonable cost - that are also non-metalic. They all seem to be aluminum or mostly brass - which will not work well over time with acidic nutrients. There are a few stainless ones, but they are $$$.
hehehehehe Im just too lazy to type out Whorled Phylotaxy, plus I keep forgetting how to spell it! Just try saying it three times fast! 
Up-date on the changes. The nozzles are all now adjusted so they dont point directly at the opposite set of roots. This is as close as I can get to the âidealâ of not spraying the root directly. There is still significant side spray that hits the roots, and no way to stop that.
The leaves initially started to droop significantly after I made the change, so I have been leaving the timing at 0.9/50 or so. That didnt seem to work, so I upped the pressure from 5 PSI to 6 PSI, and over the last few hours they have really perked up. Its hard to judge fuzzy hairs over that short a time, but I think this is going to work better.
Up-date on root trimming - that did stop them from growing down to the floor for a few days. However, this time I didnt see any large increase in side growth. Of course, other things have been going on at the same time - topping, changing nozzle positions, etc, so that could be the reason.
Im not going to mess with trimming any more this grow. Im going to just let them go down to the floor. I made another change in the chamber for this grow that I dont think I have mentioned yet. Previously, I had lined the bottom of the chamber with a piece of plastic from a garbage bag.= with a drain hole in the center feeding down to a PPM sensor. The sensor didnt work for crap, and the plastic made for puddles. The roots liked the puddles, but they lost fuzzies - it was sort of like having an NFT area in the bottom.
This time - with no plastic - Im thinking the roots will go to the bottom, try to grow through the wet fabric, then air trim when they get to the outside. We will see in a few days. The roots on all three have started back down again.
1 Like
When I started using these Delavan nozzles originally, I carefully measured the actual flow rates when they were first installed in the bottom of the chamber shooting UP. Not surprisingly, the flow rates were higher than the numbers from the (old) chart I was using because I had more head height than the chart showed.
However, my measured numbers, about 6.3 L/H was almost in the ball park of the new chart number of about 5.5-5.9 L/H at the pressures I was running.
However, I screwed up and didnt re-check the flow rates when I moved the nozzles and changed over to siphon feed. Every time I have tried since then, something happens to throw off the measurements. Mainly its the float valve. Its just not consistent enough to get a usable reading.
So, I decided to just use the numbers from the new flow chart @heathen posted earlier. Looking at the data, the relationship between pressure and flow rate is obviously not linear. Doubling the pressure does not double the flow rate. So I plotted the data out for the pressure range Im interested in and smoothed out the graph and did some interpolation.
It turns out, the flow rate changes in the pressure ranges Im playing with now - 5 to 6 PSI - are actually pretty small. Going from 5 PSI (0.35 bar) to 6 PSI (0.41 bar) is a 20% increase in pressure but the flow rate only goes up 3% - from 3.3 Liters/day to about 3.4 liters/day.
Based on that study @heathen also posted earlier and some other similar data I have seen, I am âassumingâ that means Im getting better atomization as the pressure goes up. Looking at the videos of the mist in the chamber, it sure looks visibly thicker, so if that extra visible mist isnt due to extra flow rate, it seems it must be due to smaller droplet sizes = lower SMD numbers - which is good - I hope 
Bottom line is, increasing the pressure from 5 to 6 PSI gives me more hang time with only modest increase in flow rate.
Here is the graph.
Interesting to note that from 5PSI (0.35 bar) down, the change in flow rate for any given change in pressure is more pronounced because the graph is flatter.
EDIT: forget that graph. Its been tooooo long since I played with excell - I have the horizontal scale all wrongâŚ
4 Likes
It is very pity its impossible to find any details on droplets diameter per air\water pressure relation. And probably the only way to do it - measure by ourselves: we (are going to) work with water instead of fuel with higher viscosity. It would be extremely useful to have this info: too much pressure may lead to the too fine droplets, like less than 20 microns, which is also not good.
One of the options Iâve seen is to use a speedlight + camera with very low shutter and take mist pics (more on this here). This method doesnât give precise results and require a lot of diligent work but might give more or less correct view of mist quality. The only thing I donât understand is why the guy on the video tried to compare it to a human hair. It would be much more constant to use 0.05 mm fishing line. It is even possible to span finishing lines of different sizes and compare particles in focus to them.
1 Like
True. I am judging the size by hang time, but with lots of assumptions based on comments from atomizer and others. For example, he mentioned on time that mist that hangs around for more than 5 minutes has to be sub 5 micro sized. I know for sure that droplets that immediate fall are too big - but no clue on the actual sizes.
I tried to do some calculations based on this chart for droplets of water sprayed on crops.
The major problem is that these nozzles put out a very wide range of droplets, and its impossible to judge which ones are dropping out first, second etc. All you can say is that some droplets were still there after x amount of time, but you have no way to judge or measure what % of the total is still hanging around after the rest falls to the floor. It will tell you that some of your droplets are very roughly within a certain range, but thata it.
II dont see any way we can come up with a meaningful SMD number so we can judge the over all mist characteristics.
I am not at all impressed with his technique. As you said, using hair was a bad idea to begin with, but I also have major doubts about his technique actually being able to tell what the sizes are. Every thing - hair and drops - were really out of focus. That tells me he didnt have the target items withing the correct focal distance. Small objects will have very different apparent sizes when out of focus and it makes a huge difference if they are closer or further from the lens.
I would not be surprised if his technique had errors of as much as an order of magnitude just due to the focus issue.
I think the bottom line for most folks is still going to be trial and error. You look at the mist and make your best guess - then let the plants tell you f you are close or not. Unfortunately, thats a slow and potentially costly process if you buy the wrong nozzles to start.
The large droplets in my videos look like they travel about 2 ft in 0.5 seconds or maybe less. That works out to about 4 feet/sec. The smallest droplets are still hanging after 120 seconds. The bulk of the mist seems to last roughly 50-60 seconds.
per that chart:
20 micron droplets fall at 0.04 ft/second
100 micron droplets in that chart fall at 1 ft/second
240 micron droplets fall at 1.7 ft/sec
400 micron drop at 5 ft/sec
So the rate of fall is very non-linear within the range we are interested. That makes all these calculations mostly just wild guess work, but here it is anyway
I came up with the larger droplets at around 350-400 microns and the smallest at under 5 microns. A good part of the mist does hang for at least 40 seconds, which is maybe .05 ft/sec, so Im guessing its average size is in the 50 micron range, but I still have no clue what percentage of the total water sprayed falls within that range.
The other thing that makes this kind of âtestingâ difficult is that visually, the smaller droplets show up better. I forget the exact numbers, but 1 ml of water will make millions of droplets at 20 microns, but only a few thousand at 200 microns. Thats because the volume of a sphere varies as the cube of the diameter. So a tiny bit of water made into 20 micron droplets will seem far denser to the eye than the same amount of water forming droplets that are 100 micron.
Still, I cant help running the numbers and thinking I have figured something useful out - even if it is mostly fantasy
2 Likes
Day 18
Cant sleep so time for an up-date!
Things are going well so far. I was thinking the roots are developing slower this time than the last grow, but I looked at pics from this same time and they are very similar. The plants on top however are doing much better than last time and are much larger. If this keeps up I will have no trouble filling the screen or the tent. In fact, I might run out of space, but we will see.
The big girl continues to stay in first place as far as growth of roots and leaves. She has the best fuzzies and the largest root mass and the fastest growth up top. The new branching after the top/FIM I did is coming along nicely. She will be ready for the scrog screen in a few more days if she keeps this up.
Her roots today.
The whirly bird is doing well but is growing more slowly. She is looking like she will be short and very bushy - much like the plants from last time. Ive had her tilted over to the side for a few days and some new side branching is finally getting started. She is staying very short though.
Her roots are doing fine, but are the smallest of the three by far. Its hard to tell if thats because of some lack of flow in the chamber or if its just her genetics. I suspect the genetics.
The middle child is in the middle on all counts. Second largest, second fastest, etc.
They were all looking a tad pale, so I increased EC from 0.8 to 1.0.
They all also are doing the same âdaily droopâ that most of my grows have done. Towards the end of lights ON period, the leaves on all thee just droop dramatically. Then some time during lights OUT, they all pop back up and the plants will have grown noticeably. Then they look great again until 2 to 4 hours before lights out when they start to droop again. My humidity stays on the low side when lights are ON - maybe 35%-40% and it goes up a few points lights OUT - maybe 40-45%. I suspect thats the issue, but not sure. It almost seem like they would prefer a 12/12 light schedule, but I doubt that is the issue.
6 Likes
These roots look amazing!
I review possible pressure regulator options. Found one regulator with promising specs (0.01 - 2 bar or 0.1 - 8 bar) but seems it has its own air consumption. Does your regulator consume air during work?
By the way, Iâve ordered two Chinese nozzles 1/4J - SU13 and 1/4J - SUE15. Hopefully Iâll get oil-free air compressor till they arrive.
2 Likes
I think what they are talking about is if the regulator is the relieving type or non-relieving. The relieving type vent a small amount of excess air when the pressure gets up to the set point.
Relieving & Non-Relieving Regulators
Regulators can be a relieving type or non-relieving. The application dictates which you would use.
For example, if you were regulating the pressure of a noxious or expensive gas, you would select a non-relieving regulator to prevent off-gassing of that poisonous gas into the plant atmosphere through the regulator, or the waste of an expensive gas through a relieving regulator.
Most industrial systems use a relieving regulator. With a relieving regulator, if the downstream pressure exceeded the pressure setting on the regulator for any reason, then the higher downstream pressure would be allowed to vent back through the regulator to the atmosphere.
The low pressure regulator Im using near the solenoids is non-relieving and does not vent any air. It allows the pressure against the solenoid to build up to around 10 PSI when the solenoid shuts down. That means the first pulse of air going to the nozzles starts out at around 10 PSI, but it drops quickly to the set pressure and holds for the duration of the ON cycle. A relieving type would not have that built up pressure between cycles, but I worry it might drop to a lower pressure when the solenoid is open unless its an expensive model.
The regulator that came with my compressor is the relieving type and it does vent a small amount of air each time the tank fills up to the max point and the motor shuts down.
I would worry a little about air consumption with a relieving type. You are going to be firing the nozzles anywhere from 30 to 90 times an hour depending on your final setup - every 30 seconds to every 2 minutes or so max I would guess.
I cant quite tell what the units are on the amount of air vented - is that liters/minute or? Im not sure what ANR is either - a standard atmospheric reference maybe? Google isnt helping me this morning.
Other than that, it sounds like a great regulator. Whats the price and where did you find it?
I am looking forward to seeing your results!!
2 Likes
Yep, these are litres per minute. Full specs are here.
Found what ANR is:
ANR (Atmosphere Normale de Reference) is quantity of air at conditions 1.01325 bar absolute, 20oC and 65% RH (Relative Humidity).
Iâve found these regulators on Aliexpress. Price is $13.80 plus delivery ($20.4 in overall for me).
It looks like a good enough product to put in after solenoid but donât know if itâs ok to use it at the air line entrance: I want to keep main air line pressure at ~1-2 bar more than the highest work pressure (to compensate possible loses in fittings etc). Still donât really understand how much air I will loose if put it right after compressor\tank.
Also if I use one of these valves for pressurize water tank then seems Iâll need to use two solenoids - one before regulator and one on the water line right before the nozzle to prevent leakage\pressure drops. I assume it is the same problem as with the main one: donât understand if it will bleed all the time.
Have bought 3 cheap solenoids as well. Heard in one video that they are pretty fast. Know nothing about quality though. But in that video they were used for pneumatic rifle so they at least shouldnât leak.
1 Like
Ah, thats what I suspected - standard temp and pressure reference.
How much air is lost will depend on how you set it up I think. If we assume it is bleeding air during the entire time the the solenoid is open, and your average ON time is 1 second, you will loose 4.4/60 = ,073 liters per cycle. If you do a cycle every 60 seconds, thats .073 x 60 = 4.4 liters per minute in little one second bursts.
However, I dont think it will be that bad. The way these work is IF the pressure on the down stream side is ever above the set pressure, then it vents enough air to drop it down to the set point.
The way you are going to use it, I dont think that will ever happen as there will be no real back pressure build up - the nozzle is always open so no pressure can build up.
If you put the regulator before the solenoid - like I have it - then it might vent air because the pressure is held by the closed solenoid. Each time the solenoid closed, it might create a pressure spike that would make the regulator vent. I doubt it would vent as much as I calculated above, but that would need to be tested to be sure.
The only potential issue I see with putting the regulator down stream from the solenoid is if it is fast enough to give you a âcleanâ on cycle where the pressure is reasonably unifirm during the entire ON time.
In my situation - with the regulator before the solenoid - it allows over pressure to build up on the solenoid so that when it opens, the nozzles get an initial hi pressure burst at around 10 PSI. But the pressure drops down to the regulated set value within maybe 1/10 of second or so. So the first 1/10th of a second of each cycle in my setup is at a much higher pressure.
I dont mind that too much for a couple of reasons. For one, the added flow rate is minor, and for another it will speed up the water getting sucked up from the siphon level (this wont matter to you). Finally, any water that gets sprayed at the higher pressure will be a finer mist, and thats ok with me too. Normally this kind of slop would bother me a lot, but in this case there isnt really enough downside to worry about.
Your application might actually work better than the way I have it. I might experiment with that between grows. It will depend on if the regulator is fast enough to keep the ON cycles âcleanâ. Im a little worried it will cause a slower rise and fall rate of the pressure to the nozzles. No way to tell with out testing it though.
Those solenoids look good for the air side, but might be a problem on the water side. They are brass, so any nutrients in your water will cause them to corrode pretty fast. They will also leach small amounts of copper into the water over time. How much will depend on the quality of the brass and how strong your nutrients are mixed, but roots dont like strong copper levels.
No, it will only bleed if the pressure on the down stream side is higher than the set point. If it is, then it will bleed unit the pressure matches that set point and stop.
1 Like
do you see any problems on the horizon from the perlite attached to some the roots?
regards,
mike28086
1 Like
No. I used to carefully tease out as much perlite as I could before putting the babies in the pucks, but then it occurred to me that the perlite could help with the transition period. The perlite will hold extra moisture that the roots can use while they adjust to the new environment. The last few times Ive done the transfer, Ive been careful to leave as much perlite as possible for that reason. I think it really does help, and so far, I have seen no downside to doing it this way.
4 Likes
Ive tried lowering the temp in the tent by a few degrees - from a hi of 82-84F down to 77-78F. That has raised the RH up from the mid 30âs to the mid 40âs. That seems to have helped to a small degree, but the droop is still there and still pretty dramatic.
Im toying with options to pump some of that 100% RH air from my root chamber up into the grow zone, but Im worried about drying out the root zone. Have to think about that some more.
Other than that, all is going well with no other issues. Its LITFA time and rather boring
3 Likes
Howâs the emergency anti-tamper alarm system working out? Flawless grow, I say. Flawless.
2 Likes
LOL! Its funny that since I installed the alarm, I havenât forgotten to turn things back on - not once! Just having the alarm in place seems to be enough to keep me from forgetting. It helps that as soon as I flip the switch to the OFF position, the alarm gives a short beep, which always makes me think - âoh yeah, dont forgetâ. So it kind of works even without having to go off full blast. Either way, its keeping me from messing up - at least in that specific way. Im sure I can find something else to screw up of I work at it
3 Likes
Well crap. Houston, I think we have a problem.
Those are from the two normal babies. I cant tell yet on the whirly bird - its way to crowded to see well.
The question is what to do now. Toss them or pinch off the boy parts and hope? I dont smoke, so I dont care about seeds in the bud, but I am worried about over all yield.
This is the first time Ive seen it like this. Suggestions?
4 Likes