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 Need suggestions for a needle valve
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| Omega |
Posted on 09/19/2014 6:21 PM
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 1/4 Pounder  Posts: 132 Joined: June 13, 2014 |
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. I appreciate any suggestions you fellows (and ladies) might have. Barry |
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| allenb |
Posted on 09/19/2014 10:01 PM
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 Administrator  Posts: 3725 Joined: February 23, 2010 |
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
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| Omega |
Posted on 09/19/2014 10:11 PM
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1/4 Pounder Posts: 132 Joined: June 13, 2014 |
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! Barry |
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| JackH |
Posted on 09/20/2014 6:46 AM
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 Administrator Posts: 1809 Joined: May 10, 2011 |
I was wondering what the larger commercial gas roasters use. Maybe they don't need the precision?
---Jack
KKTO Roaster. |
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| allenb |
Posted on 09/20/2014 11:48 AM
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Administrator Posts: 3725 Joined: February 23, 2010 |
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
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| Omega |
Posted on 09/20/2014 11:02 PM
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1/4 Pounder Posts: 132 Joined: June 13, 2014 |
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 |
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| allenb |
Posted on 09/21/2014 10:32 AM
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Administrator Posts: 3725 Joined: February 23, 2010 |
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
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| Omega |
Posted on 09/25/2014 10:25 PM
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1/4 Pounder Posts: 132 Joined: June 13, 2014 |
Have you heard from the Parker people about suitable needle valves yet?  Barry |
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| allenb |
Posted on 09/25/2014 10:39 PM
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Administrator Posts: 3725 Joined: February 23, 2010 |
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
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| allenb |
Posted on 10/02/2014 10:09 PM
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Administrator Posts: 3725 Joined: February 23, 2010 |
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
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| Omega |
Posted on 10/02/2014 10:23 PM
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1/4 Pounder Posts: 132 Joined: June 13, 2014 |
That's good news, Allen! Thanks for your perseverance and "Mr. Parker's" diligence! Barry (Important note: with this post (my 50th) I graduated from being a "Newbie"!!  |
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| allenb |
Posted on 10/07/2014 10:23 PM
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Administrator Posts: 3725 Joined: February 23, 2010 |
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
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| Omega |
Posted on 10/07/2014 11:03 PM
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1/4 Pounder Posts: 132 Joined: June 13, 2014 |
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 |
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| allenb |
Posted on 10/08/2014 8:56 PM
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Administrator Posts: 3725 Joined: February 23, 2010 |
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
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| allenb |
Posted on 10/10/2014 5:31 PM
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Administrator Posts: 3725 Joined: February 23, 2010 |
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:
Edited by allenb on 10/10/2014 5:37 PM 1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
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| Omega |
Posted on 10/10/2014 9:51 PM
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1/4 Pounder Posts: 132 Joined: June 13, 2014 |
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 |
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| allenb |
Posted on 10/11/2014 11:25 AM
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Administrator Posts: 3725 Joined: February 23, 2010 |
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:
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
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| snwcmpr |
Posted on 01/06/2016 9:10 AM
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 1 1/2 Pounder  Posts: 925 Joined: March 03, 2011 |
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. Quote 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". |
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| allenb |
Posted on 01/06/2016 7:18 PM
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Administrator Posts: 3725 Joined: February 23, 2010 |
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
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| BenKeith |
Posted on 01/06/2016 7:38 PM
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 Pounder  Posts: 485 Joined: April 21, 2014 |
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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| allenb |
Posted on 01/06/2016 7:59 PM
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Administrator Posts: 3725 Joined: February 23, 2010 |
BenKeith wrote: Quote 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. That sounds like an effective way of getting precision turn-down without resorting to a 50 turn, very expensive precision metering valve. Fortunately, for burner control on a roaster, one multi-turn valve with appropriate Cv value will give one plenty of precision by itself. Allen 1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
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| snwcmpr |
Posted on 01/08/2016 11:06 AM
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1 1/2 Pounder Posts: 925 Joined: March 03, 2011 |
Summit Flow Control has been purchased by, or absorbed by, Instaloy. I am awaiting some information back from them. Generant replied to my email inquiry, and says that the PMV-1B-K is available. I am awaiting more information from them also. 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". |
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| snwcmpr |
Posted on 01/08/2016 11:23 AM
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1 1/2 Pounder Posts: 925 Joined: March 03, 2011 |
Generant responded and said to contact Adrienne at Installoy. Adrienne Gurrola Inside Sales Representative | [email protected] Mobile: 936-760-6511 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". |
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| snwcmpr |
Posted on 01/08/2016 12:42 PM
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1 1/2 Pounder Posts: 925 Joined: March 03, 2011 |
I did get a reply from Adrienne. And I think you may best to contact her directly. It was a bit too 'Company Formal' for me. A lot of documents attached, and she will offer a quote. And, I think I am going to go the way of the Kelly Valve and Driver board. 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". |
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| snwcmpr |
Posted on 02/02/2016 1:53 PM
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1 1/2 Pounder Posts: 925 Joined: March 03, 2011 |
Update: I am now starting to think I want this Generant Valve, PMV-1-B-K. I have initiated contact with Installoy again. 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". |
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