PID forge upgrade (videos added)

you know ... if you are mostly going to be near the thing - wont you hear if the blower stops running (for whatever reason)? if so, why not use (if you do not already have ) a nice big red "emergency shutoff" switch???? The only other things I can think of (right now at least) involve directly sensing whether there is flow using that flow sensor to drive a relay that drives the gas flow, and .... you definitely do not want to go there :)
 
Just to be clear, when we refer to a solenoid in a forge build we are talking about a gas solenoid valve. ASCO 8040 and 82XX series are the right types for Propane/LP/natural gas.
 
Thanks Stacy. That's what I found, but it seems as if neither of these comes in a 3-way configuration. According to the ASCO website, I'd need a 362, 364 or 562 series?
 
3 way would work fine, but a two-way and the by-pass line does the same thing as easily and much cheaper. 3-way os more necessary in pneumatic controls and in distribution systems.
 
Stacy E. Apelt - Bladesmith said:
3 way would work fine, but a two-way and the by-pass line does the same thing as easily and much cheaper.
Click to expand...

Ahhh...I get it! (Amazing how the brain works. I've seen this mentioned a few times and it didn't really 'click' until just now, so much for my Master's degree, duh:rolleyes:...) Just to be sure, you're saying the bypass line would be the "low flow" line, and the 2-way solenoid would be the "high flow" line, simply opening and adding more gas when the temp drops, right? (and yes, this would be significantly cheaper).
 
Yes.
The LOW flow by-pass is manually adjusted by the LOW needle valve to run the forge about 100° below the desired temperature ( 1400°F is a good spot). This level of gas is always flowing. Consider it the idle flame setting.
The HIGH flow is turned on and off by the solenoid. With the solenoid in the open position (by turning the solenoid switch to SET *) you adjust the HIGH needle valve to run the forge above the desired target (say, 1700°F if doing HT). The high level is extra gas provided by the solenoid when a little more heat is needed. Instead of slamming the forge into max burner output every time the solenoid turns on, it gently adds more heat.
When the PID is set to the desired target (as long as it is within the pre-setting range) the flame will cycle from LOW to HIGH. This keeps the max-high and min-low fairly close and the controller does a better job of keeping the temp tight.


* I added a switch that turns the solenoid ON and holds it open. This allows setting the HIGH level without having to change the PID target like my old instructions said. After setting the HIGH level max, turn this switch RUN.
 
Cushing H. said:
you know ... if you are mostly going to be near the thing - wont you hear if the blower stops running ...?
Click to expand...

Yes, but the important word here is, mostly. And even if the correct word was always, that's still not good enough for me. About 4-5 years ago, I was at the anvil when we had a power failure, and in the time it took me to react and get to the shut-off, a backflash (is this the right term?) blew the baffle off my blower.

Stacy E. Apelt - Bladesmith said:
* I added a switch that turns the solenoid ON and holds it open. This allows setting the HIGH level without having to change the PID target like my old instructions said. After setting the HIGH level max, turn this switch RUN.
Click to expand...

Good idea, thanks! Last night I found/ordered 2 ASCO 8215G020 for $55 ea on ebay, and they should work nicely with this idea.
 
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Hello all. After numerous versions, I think I have the final wiring schematic done. Hopefully the valves will arrive in the next day or so...
Wiringschem1.jpg
Let me know if you see any corrections.
 
The SPST switch is in backwards (just kidding).

Looks good.

You might consider a TPDT center-off switch and have the extra terminals light a red light for PID control (SSR side) or a yellow light for by-pass (direct line side). That way you will know which way the switch is set with no doubt. In the center-off position, it disables the solenoid to allow the LOW needle valve adjustments while the PID is ON.

https://www.ebay.com/itm/TPDT-Triple-3-Pole-Double-Throw-3PDT-9-Pin-ON-OFF-ON-15a-Toggle-Switch/171765017470?
 
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Stacy, when you've got a long link from ebay or amazon you might shorten it a bit by removing all the extra stuff and make it look something like this: https://www.ebay.com/itm/171765017470
The link can actually be shortened to only ebay.com/itm/171765017470 (the last numbers is the ebay item number)

Amazon is the same format except use "dp" rather than the "itm" of ebay. For ebay they sometimes use different letters between the two /.../ and it can change. Just use what they have there. For Amazon you might have to change the letters between "/.../" to dp, but that seems to work.
 
Yeah, I didn't spot that it printed out the whole address. It first showed only a shortened version. I changed it back.
 
Good morning, all. I've finally gotten a buddy over to help me lift the forge onto the remodeled stand, and am getting ready to plumb in the propane, and have one last (hopefully) question. Is there a problem with having to plumb a U-bend in the propane line before it enters the air pipe from the blower to the burner? I don't think so, because the propane flow is driven by pressure, but just want to check.
Top View.jpg
 
Thanks Stacy. I'll have to think about that.

Another couple of questions for y'all as I'm starting to think about plumbing this up, hopefully using stuff I have lying around.
1) Is there any problem changing pipe diameters in the middle of the system? (For example, going from 3/8" to 1/2" then back to 3/8"?

2) Is it ok to use a T-fitting for the final connection of the HI flow to the idle line or should I get a Y-fitting?

Thanks
 
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Smaller pipe will give you more flow resistance = lower flame. I don’t see a problem with shifting sizes as long as you don’t go to anything smaller than the original plans suggest.

Same thing with T fitting - somewhat more flow resistance, but my guess is the difference will be in the noise...
 
I agree with Cushing. In a build like this there are no issues with your questions. The gas is a low flow rate anyway, so resistance is moot.
 
Just out of curiosity, what keeps these things, when running, from flashing back into the gas/air feeder tube - especially when you just have a straight open tube into the forge (and not a ribbon burner)?
 
Manifold pressure from the blower.

If you crank the blower down too much and cut the gas to a bare flow the burner will sputter, and may go out, but flash-back isn't an issue with a blown burner.
 
Stacy E. Apelt - Bladesmith said:
Manifold pressure from the blower.

If you crank the blower down too much and cut the gas to a bare flow the burner will sputter, and may go out, but flash-back isn't an issue with a blown burner.
Click to expand...
Huh. is there any understanding on the speed of the flame front? I take it that while in the feed-pipe the velocity is higher than the flame front speed - so that you only get the flame when the flow slows down as it enters the forge? What I am really heading towards is how far away from that situation is the current standard set up - and how large a feed pipe can you go to before you are close to that "edge"?
 
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