What do I need to look for in a gas Solenoid Valve ?

D

Dixieblade57

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Jun 20, 2007
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I have plans in the future to convert my propane forge from a manual set up to one controlled by a PID using gas solenoids. Here is my present set-up.
forge002.jpg


My setup has a pressure gauge at the regulator to monitor the incoming pressure and each burner has it's own individual pressure gauge to monitor the pressure that is controlled by the shut off valves, going to each individual burner. That way I can increase and decrease the amount of gas to control the heat from each burner!
forge004.jpg


I am trying to learn what I need to be looking for in gas solenoids! So school is in session, someone school me on the correct designations I am going to need so I can be looking for the best deal on the right gas solenoid valves!

I know Asco Red Hat Solenoid Valves are supposed to be among the best. I also know that I need one with 3/8" pipe fittings to match up with my plumbing on my forge.

1. How do I tell the designation that works with propane gas, that I am using on my forge?

2. Is there anything else I need to be watching for when buying a solenoid valve?

3. Is there a way to program into the PID a sequence that will allow me to punch a button on the PID and it will drop the gas flow back to basically and idler circuit/operation,( in other words just enough gas flow to keep it lit)?

4. Is there anything I need to be aware of on the plumbing to get the system to work correctly?

I am sure I may have more questions later but this is all I can think of at this time!
 
You want to purchase a solenoid rated for Fuel Gas and/or LP gas. There is a difference in the type of seals. There are lots of cheaper ones on ebay and other places, but they are rated for gas/air/light oil.
The right ones will be LP Gas/Fuel Gas; NC; two-way
The BTU capacity is the price determiner.

You can get simple 12VDC solenoids from about $35-65. The good 120VAC ones are more robust, and will cost from $75-150. The price range depends on your source and the capacity of the valve.

ASCO 8040 and 82XX series are a good choice.
http://www.ascovalve.com/Applications/Products/FuelGasOilSolenoidValvesData.aspx

Now, I know there are many who have built a control with the cheaper regular 15PSI gas solenoid (non-LP), including me. That does not mean they are the right valve. For the difference of $50 or less, do you want to risk it?????
 
Last edited:
Stacy,
Is there something about the particular application that makes 120vac valves prefered over 12vdc - other than not requiring a 12vdc power supply?
Thx
Steve
 
No, DC valves are fine. You just have to have the DC power. There are low price DC shut-off valves on ebay, but my thoughts are that they won't last very long, as they aren't designed to cycle on and off repeatedly.

Another feature to check on when selecting the solenoid is the BTU capacity. A pilot valve is much lower cost than a control valve, but will only handle 1/3 the BTU gas flow. A forge like Dixie has will require at least 150,000 BTU solenoids.

BTW, it was 8040 series valves I used last time. To be exact, 8040G021( control valve) on a full forge, and 8040H007 ( pilot valve) on a smaller HT forge.
 
Bldsmth, thx for the clarification, and the part numbers as well. I need to crunch some numbers, but think the pilot valve may have a use.
 
Thanks for the info everyone. Stacy I like info like that. I always tried to buy the best when I was doing construction now days my budget tends to limit me but I look at it this way. If I know what it is I want I can start saving for it. I have learned over the years that just building something to get it into use is not always the cheapest way. It may save you money in the short run but cost you money in the long run!

I have another question that has arose out of another thread on another forum. Given the I use the right solenoid valve how closely can I expect the PID to hold temp?

Now I realize that there are more variables in this question such as the thermocouple I am using, etc., etc..............

This other thread speaks of the following. "I set the PID at 1475F, and the temp varies from 1300F to 1550F!" What can I do to make it "dead on?" Another maker who I have the up most respect for replied like this! Short of experimenting with ALL the variables, and "sizing" EACH component to "match", which is a lengthy and expensive process, there's nothing you can do. So many things come into play.....the question is impossible to answer!

So here is the 50 million dollar question:
How closely will a PID controller hold the temp on a forge using gas solenoids?????????
 
With a two-stage blown setup, and allowing the forge to fully soak, temperatures can hold as close as +/- 1 degree. To keep the solenoid from constantly cycling on/off , set the PID for 3 degree +/-range, and it holds within a few degrees of the target.

Also, a PID is an intelligent device. It has to learn by experience. After it has run for a while, it figures out how long to fire the burners, and how long to wait between firings. This will slowly allow it to fine tune so it doesn't have big swings.
The first time you drove, you stomped on the gas and slammed on the brakes, making the car drive jerky. After a little while, you learned how hard to press the gas pedal, and when to press the brake....the car drove smoother.

Rosemary Rae's words for the day are:
Fully Soaked Forge - allow 10-15 minutes warm up
Time To Learn - The PID should have it figured out by the time the forge is soaked.
Give it some room to work in - allow a few degrees swing.
 
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