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CharcoalRoaster
11/04/2019 1:58 AM
+1 snwcmpr

snwcmpr
11/03/2019 2:16 AM
Can we make the shoutbox UNAVAILABLE until a member has a certain number of posts?

allenb
11/01/2019 2:20 AM
Funopt, please post in the gas and electric heat sources forum

Funopt
10/30/2019 5:17 AM
Can someone help me for using forced propane burner as my heating element. I rather want to use lpg than electric. Do you think it would work

snwcmpr
10/22/2019 5:31 AM
Thanks to you all....... I was not sleeping ... I stayed awake worried about it all. :)

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Need suggestions for a needle valve
Omega
I've been having good success with my recently built roaster, but would like to get a needle valve with better resolution, ie finer control. The pressure range would be 10 to 20 psi. I'm using a no-name 1/8" needle valve as seen in the pic below. A one psi change in pressure is very hard to accomplish, as the present valve overshoots quite a lot.

i44.photobucket.com/albums/f44/barryk52/Gas%20fired%20roaster%201/Gasfiredroaster004_zpsc9568380.jpg

I appreciate any suggestions you fellows (and ladies) might have.

Barry
 
allenb
Hey Barry, timely question as I'm currently researching this issue. I'm conversing with an engineer from Parker valves to try and come up with a set of formulas that will allow us to select a needle valve that will provide good linear control of our burners without taking 20 turns to achieve full output or going from low flame to full power in 1/2 rev. I'm hoping to get an answer in the next few days and will post the results as soon as I get them.

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
Omega
Terrific, Allen! I can't wait to see what you come up with. An engineered solution to this problem is much better than an expensive trial and error, wild goose chase!

ThumbsUp

Barry
 
JackH
I was wondering what the larger commercial gas roasters use. Maybe they don't need the precision?
---Jack

KKTO Roaster.
 
allenb
That's a good question. I've seen all sorts of variations on commercial roasters. Multiple, staged burners with no manually controllable valve for varying pressure, staged with hand valve for adjusting pressure, hand valve only on single burner. The hand valves are nothing fancy but I'm sure they are sized so one doesn't have to make numerous turns nor a half turn for going from low fire to high fire.

Unfortunately, for our small BTU burners, going from a needle valve with a .015" seat orifice to a .018" seat or even going from a 15 degree needle taper to a 20 degree taper causes huge changes in number of turns versus flow rate. Fortunately, the valve manufacturers provide tables and formulas that allows someone who can interpret them to zero in on just the right needle and seat to give you your preferred turns ratio.

I'd like to throw a question out there to everyone, what would be your preferred ideal number of turns from minimum fire to max firing rate?

I was assuming no more than 2 turns and that one turn would be a little too coarse?

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
Omega
I would be very happy with either 1 or 2 turns! The pressure range that I'm using now is between 12 and 16 psi. With the current valve, the adjustment from 12 to 16 is done in about 1/5th turn, which is way too course.

If I could span 4 psi in 1 turn, that would be a huge improvement! A 2 turn valve would't be a bad thing, either, IMO. However, the merits of each would only become apparent with use over time, and it would come down to personal preference, since either would work.

Barry
 
allenb
1/5th turn is indeed too coarse! It's unfortunate that many hardware outlets and many manufacturers of valves identify small brass shutoff valves as needle valves when they don't have anything resembling a "needle". I bought one for one of my roasters thinking it was what they described it as but upon disassembling it I found a crudely made barrel shaped disc instead. It performed close to what you found and went to full output in maybe a 1/4 turn.

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
Omega
Have you heard from the Parker people about suitable needle valves yet? cross fingers


Barry
 
allenb
I got an email from him today telling me he unfortunately had to go to Houston to work a project but as soon as he gets back to Denver he will put the formulas together for us. It sounded like it would be very soon so lets keep our fingers crossed.

In the mean time to allow you to have some better control while waiting on the info from him, have you attempted reducing your pressure down to 15 or 12 psi to the valve to see if it might allow a little finer control? I know there's a practical limit where if you go too low then you can't hit the highest output needed for the roast.

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
allenb
Update: Received an email from him today and he's very close to having the spreadsheet completed. I guess with all the variables I threw at him it made it quite a challenge. I'll post as soon as it arrives in my email and I've had a chance to digest it.

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
Omega
That's good news, Allen! Thanks for your perseverance and "Mr. Parker's" diligence!

ThumbsUp

Barry

(Important note: with this post (my 50th) I graduated from being a "Newbie"!!

greenman
 
allenb
Sorry for the additional delay Barry. He's had to make some refinements to the spreadsheet and is taking longer than expected. In the meantime, I've immersed myself in the engineering aspects of all of this to the point where I can make a selection for you while we're waiting for the finished product to arrive.

Let me do some math and call Parker valves tomorrow and see what we can come up with. I'm going to use 16 psi for a high fire pressure and .0145" (#79 drill) as the burner jet size to run through the BTU calculator to come up with cu ft/hr. This should allow me to find a good fit. I'm going to shoot for somewhere between 2 and 4 turns to full output.

Oh, let me know what you require for inlet and outlet plumbing. I'm assuming we can go with 1/8 female pipe?

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
Omega
Hi Allen, I can use either 1/8" or 1/4 female NPT on the valve. Or whatever is available, my setup is quite modular and adaptable.

Thanks for being diligent to pursue this!

Barry
 
allenb
The first response from my inquiry was from Generant and the least costly model they've got that will work with our low flow rates is this valve:

http://www.genera.../PMV.shtml

It meets the number of turns we're asking for at the correct Cv value which is around .0095 to .010. Cost is $72.00 plus shipping at a lead time of 5-6 weeks but can make it 2 wks for a little more $. Unfortunately, to find a new valve that can handle the low flow rates we use and provide decent turn-down is a little pricey.

I'm hoping to get a response from the engineer from Parker and also Graingers tomorrow on alternatives. Another option will be Ebay who seems to have quite a selection of high quality needle and metering valves but finding a used one with this Cv value at less than 10 turns might prove difficult.

Stay tuned!

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
allenb
I made some headway today on zeroing in on a valve for you. I located a shop near Houston Texas that carries the PMV series from Generant that should be a fit for your roaster. The real good news is they have lots of them in stock and price is less than the previous quote of $72.00. They can sell you one for $62.00 plus shipping. This valve should give you full burner output by 5 or 6 turns and hopefully less. I'm going to try and get the spreadsheet posted in the next few days. BTW, the best Parker could do for a valve in the correct Cv value was a valve costing $300.00!

Part # is PMV-1B-K and is available through

Summit Flow Controls
13460 Snow Ln, Willis, Texas 77318
PH:936-890-8711

Allen
allenb attached the following image:
pmv3_400x400.jpg

Edited by allenb on 10/10/2014 11:37 AM
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
Omega
That looks like a very nice needle valve, Allen. I'm sure that there are a lot of us that could benefit from better gas control and now we've got a great answer to the question of what to use.

Barry
 
allenb
If you decide to shop around for deals on ebay or elsewhere, here's the Cv/turns chart for the PMV valve from Generant and any valve with flow characteristics similar to this should work well for the gas flow in a 1 lb fluidbed according to the experts I spoke with. Something to avoid in any valve is abrupt zig zags or spikes in the Cv chart line in the preferred area of the curve. Some valves go along fine up through 3 or 4 turns and then the line shoots almost vertical for a bit before resuming a reasonable curve.
allenb attached the following image:
pmv_chart.jpg

1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
snwcmpr
I am not making a new thread because it seems I would like this updated, and ask a question.
The part number referenced above does not seem valid any longer.
Part # is PMV-1B-K and is available through

Summit Flow Controls
13460 Snow Ln, Willis, Texas 77318
PH:936-890-8711

I have searched the internet and do not know enough to say what a good alternative is.

At the expense of giving too many details, I am thinking this may be a good alternative to the current valve on the 1 lb air roaster I received from AllenB.
I just started searching, and have not done enough to say there is or is not another valve posted somewhere else on this forum, so if so, a link here may help.

Thanks,
Ken in NC
--------------
Backwoods Roaster
"I wish I could taste as well as I wish I could roast."

As Abraham Lincoln said "Do not trust everything you read on the internet".
 
allenb
Ken,

If I remember right, the PMV-1B-K was not listed on their site but a cut sheet was emailed to me back when that post was made. Have you called them to see if they still supply it. Some of the valves sold by the smaller companies are not normally in stock but are assembled after an order is placed.

If you haven't called them, do so and if they don't carry that one anymore, ask them if they can supply you one with similar specs.

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
BenKeith
I have not gotten into having to control the gas burner to a coffee roaster but through my years working in different types of plants, when I needed very precise metering through manual valves, I always did it with two valves in parallel. One main valve to get the flow pretty close while the other, much smaller valve is in the center of it's range. Once the main valve has it close, the much smaller valve makes it a whole lot simpler to tweak that last little precise amount you need.
 
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