Dr. Bob's multi purpose curing chamber in planning

[DrBob]

This is a photo of my curing chamber as it looks today. It has gotten a well used look after 3 and a half years. This is a load of virginia that has been cured off and is ready to shred. As long as it is freezing in the garage there is no rush but I will probably shred it in the next day or so. Before I convert it to a flue cure machine it will have to be scrubbed out and disinfected again. I estimate that the chamber has run 7,500 hours at 125 degrees the door seals are still good, and the plastic trim strips around the door opening still look ok with little warpage. During the first month of testing I ran the chamber at 165 for a week just to see what would happen. That was the upper limit of my thermostat. This was done in july and the temps in the garage were about 80f. You can see the added insulation on the chamber that I glued on also.

 

[leverhead]

This link has a quick view of putting a rack of tobacco together at about 7:20 in the video. It doesn't show them piling the leaf in, but it does show the pins in the rack that hold the tobacco. It also shows them loading the racks into the "barn". There's some other interesting stuff in it.

http://www.youtube.com/watch?v=ME5jXOu5A40&NR=1&feature=endscreen

 

[LeftyRighty]

thanks - that explains a lot. And that is some pretty dense loading in those racks.
My plan is to string leaf on a wire, with the wire tied to a rod spanning across the chamber. I'm guessing 40 to 50 leaves max in a 2 ft string. This is the same as stringing leaf for air-curing, except I'll pack the leaf tightly, no space between leaf stems. I don't think this is anywhere near the density of those racks, and I'll have lots of air-space between strings, as the leaf wilts and dries.

Based on prior use of a 4" inline duct fan (another application), these fans are low power, and I figure I'll be lucky to get 15-20 cfm in this application, which would be about what I need. I could always add a 2nd inline fan at top if I need the extra push. I'm still thinking 2 ducts, one each side. Duct material will be ABS/PVC thin-wall, because ells, tees, wye's are available. Also open to alternative cheap fans, please feel free to suggest them.

I will be adding a damper/valve in the duct at the top, to reduce/cut off flow in the drying phase.
It also would be easy to wrap these ducts with blanket insulation, during the drying phase, to reduce heat loss, but still keep the fans running.

Controlling heat will be easy, and not too difficult to keep efficient, with proper insulation, since I'm recirculating hot air. Contolling RH is the problem, and removing it in the drying phase, and will probably happen by accident.

 

[LeftyRighty]

another dumb idea ???
It is possible to get 3, maybe 4, strings in each layer in my small chamber, doubling the leaf being flue-cured in each cycle.
If, when stringing leaf on the wire/rod, string 3 or 4 wires at the same time, side-by-side, with leaf lamina overlapping the adjacent string, the whole thing in a rack/frame. Could really bump the density with this!
(edit) this is how I'll get to that 10#/sf density !
Now, I just need a fan that can push 1/2 cfm per lbs.

 

[DrBob]

flue curing is 6 months away. that gives us 6 months to figgure this out... this is small scale curing. Just because it has been done 1 way it does not mean it is the only way.
The old school way of ferment curing was the pile method. not any more.. I believe that a different way is possible for flue curing on a small scale. not 4 tons at a time. 4# at a time give or take. If I wreck 4# of tobaccco oh well.. 4000# that is a different thing altogether.

 

[DrBob]

thanks - that explains a lot. And that is some pretty dense loading in those racks.
My plan is to string leaf on a wire, with the wire tied to a rod spanning across the chamber. I'm guessing 40 to 50 leaves max in a 2 ft string. This is the same as stringing leaf for air-curing, except I'll pack the leaf tightly, no space between leaf stems. I don't think this is anywhere near the density of those racks, and I'll have lots of air-space between strings, as the leaf wilts and dries.

Based on prior use of a 4" inline duct fan (another application), these fans are low power, and I figure I'll be lucky to get 15-20 cfm in this application, which would be about what I need. I could always add a 2nd inline fan at top if I need the extra push. I'm still thinking 2 ducts, one each side. Duct material will be ABS/PVC thin-wall, because ells, tees, wye's are available. Also open to alternative cheap fans, please feel free to suggest them.

I will be adding a damper/valve in the duct at the top, to reduce/cut off flow in the drying phase.
It also would be easy to wrap these ducts with blanket insulation, during the drying phase, to reduce heat loss, but still keep the fans running.

Controlling heat will be easy, and not too difficult to keep efficient, with proper insulation, since I'm recirculating hot air. Contolling RH is the problem, and removing it in the drying phase, and will probably happen by accident.

I think you are 200% of capacity well never mind, I just watched the video,

 

[leverhead]

It's a crappy picture, but this is how I racked the first run in the fridge. I pushed the leaf stem up through the rack that came with the fridge and put a pin though the stem, the pin was made from a piece of thin fence wire. The second run I did basically the same thing but went side to side instead of front to back.


If I had more leaf available at the time, I could have gone to 10 Lbs/sq ft per layer. You might consider looking squirrel cage fans, there's allot of information on them and they're fairly common.

 

[DrBob]

If you had 40# of leaf in the unit it would dictate 20cfm airflow. 1 air change per minute. Floor registers for home furnaces usually are 100 cfm as a reference

 

[LeftyRighty]

I don't think the el cheapo inline fan that I referenced earlier will do the job. Not enouch capacity/power and probably won't last long pushing hot/wet air. I been doing internet search for a better option, and am now thinking one fan on top, wyed to two standpipes, and let imbalances work themselves out in the curing-camber. I like the following, albeit pricey, lots of power, cfm, and speed control is available (variable speed is nice, can adjust fan for leaf density) - but motor only rated to 140 degrees.:
http://www.ebay.com/itm/4-Inch-200-...236?pt=LH_DefaultDomain_0&hash=item3f18257f3c
http://www.ebay.com/itm/Plug-In-Spe...130?pt=LH_DefaultDomain_0&hash=item41666fe012
Am still looking for better option, cheaper, and can take hot/wet.

(edit) also thinking of just one fan (on top), and one condensing standpipie - simpler construction and should work.
For what it's worth - 200 cfm fan, with pipe flow restrictions, etc to get to 20 cfm - that is still about 4 ft/second velocity in a 4"pipe ......50 cfm = 10 ft/sec.....maybe need a 6" standpipe.

 

[COLIN]

I intend to use this lab oven it is made out off stainless has a fan and a element

Colin

 

[DrBob]

that should work just fine

 

[Knucklehead]

I want to say my bathroom exhaust fan is 500 cfm but that's from memory and I could be wrong. Anyway you can get different cfm and they are designed for humidity. May have to work with the heat situation. Chicken would call it a poop fan. Broan makes good ones and quiet.

There is a 110 cfm poop fan at Lowes with built in 1500 watt heater. Also has two 60 watt light bulbs. If more is needed you could have one pushing and one pulling. Heating incoming and recycled outgoing air. Recommended room size 100 sq. Ft. For one.

There is a 100 cfm with no heater but with built in humidity sensor. I am trying to download operators manual but I am on a tablet at the moment. We'll see.

You are also going to need a downpipe in your duct work to collect water and a valve to drain it.

 

[LeftyRighty]

COLIN.......that's a nice find. Wish I was lucky enough to get one of those, would make a great curing-chamber. It's taken me 4 years to get an ole freezer, and now I got two.

 

[Knucklehead]

I think the cfm argument will have to be resolved by going higher than you think you need and controlling the fan speed with a rheostat while you experiment to find the sweet spot.

 

[Knucklehead]

Get the NZ guys interested. They have green leaf NOW.

 

[Knucklehead]

I hope you know what they were experimenting on with that. lol

 

[leverhead]

I hope you know what they were experimenting on with that. lol

If it doesn't kill you, it might only make your tool shorter or longer.

 

[DrBob]

I want to say my bathroom exhaust fan is 500 cfm but that's from memory and I could be wrong. Anyway you can get different cfm and they are designed for humidity. May have to work with the heat situation. Chicken would call it a poop fan. Broan makes good ones and quiet.

There is a 110 cfm poop fan at Lowes with built in 1500 watt heater. Also has two 60 watt light bulbs. If more is needed you could have one pushing and one pulling. Heating incoming and recycled outgoing air. Recommended room size 100 sq. Ft. For one.

There is a 100 cfm with no heater but with built in humidity sensor. I am trying to download operators manual but I am on a tablet at the moment. We'll see.

You are also going to need a downpipe in your duct work to collect water and a valve to drain it.

bathroom fans are usually 50 cfm

 

[Knucklehead]

bathroom fans are usually 50 cfm

Lowe's has one that is 110 cfm with built in 1500 watt heater. They vary in cfm because bathrooms vary in size. The 110 cfm is for 100 square feet . You can get fan only, fan with heat, or fan with humidity sensor. 140 cfm fan only was the most cfm on Lowe's website. I just got a tablet and don't know how to copy and paste.

70 cfm with 250 watt heater -- $59.00
Up to 110 cfm with 1500 watt heater -- $350.00
Prices and sizes in between

 

[Knucklehead]

I don't know how much cfm the fan is but a stove vent would handle heat and humidity. Or rob the fan from a convection oven.,.

The ventless stove hoods have a charcoal filter and are vented back in the house. They are sized to fit the width of various cooktops or stoves. The most popular sizes are 30" and 36". You could use vent and all inside the chamber to direct air or just rob the fan.

The vented kind run a vent out the roof.

I'm just looking for common fans that are resistant to heat and humidity. The poop fan has the option of a built in heater that must also be humidity resistant because they recommend over tub mounting.