Temp Controller for Pressure Pot

[vtgaryw]

Has anyone tried to use a temp controller/thermocouple to keep their pressure pot at the right temp? I'd use something like this:

https://www.ebay.com/itm/10A-110V-Digital-Temperature-Controller-Temp-Sensor-Thermostat-Control-Relay-US/141731449329?epid=595245028&hash=item20ffda49f1:g:~loAAOSw3ydVuZEX:rk:2f:0

I use one to turn a diaphragm pump on and off for my backyard sugaring operation. My only question is how to get a thermocouple wire into the pressure pot without creating a leak.

-gary

 

[cjester]

Has anyone tried to use a temp controller/thermocouple to keep their pressure pot at the right temp? I'd use something like this:

https://www.ebay.com/itm/10A-110V-Digital-Temperature-Controller-Temp-Sensor-Thermostat-Control-Relay-US/141731449329?epid=595245028&hash=item20ffda49f1:g:~loAAOSw3ydVuZEX:rk:2f:0

I use one to turn a diaphragm pump on and off for my backyard sugaring operation. My only question is how to get a thermocouple wire into the pressure pot without creating a leak.

-gary

Here's my first thought. Maybe not super accurate, but hopefully close enough to do. Drop a thermometer inside the pot. Tape the thermocouple to the outside, and wrap some insulation around it. Get the inside to the temp you want (no pressure, just warm it to target temp), read the temp on the thermocouple. That's now your thermocouple target.

Alternately, there are thermocouple plugs available. https://www.omega.com/pptst/TC-NPT.html

 

[TattooedTurner]

As a warning, it will increase the pressure inside the pot as the air expands when heated. I leave mine outside in our desert temps during the summer and the pressure has increased as much as 12psi. Granted, the extreme temp difference between the cold air from the compressor and our grueling heat is to blame, and your increase probably won't be nearly that much, but you may want to drop it a few psi when pressurizing until you know how much it will go up.

 

[robutacion]

Has anyone tried to use a temp controller/thermocouple to keep their pressure pot at the right temp? I'd use something like this:

https://www.ebay.com/itm/10A-110V-Digital-Temperature-Controller-Temp-Sensor-Thermostat-Control-Relay-US/141731449329?epid=595245028&hash=item20ffda49f1:g:~loAAOSw3ydVuZEX:rk:2f:0

I use one to turn a diaphragm pump on and off for my backyard sugaring operation. My only question is how to get a thermocouple wire into the pressure pot without creating a leak.

-gary

Here's my first thought. Maybe not super accurate, but hopefully close enough to do. Drop a thermometer inside the pot. Tape the thermocouple to the outside, and wrap some insulation around it. Get the inside to the temp you want (no pressure, just warm it to target temp), read the temp on the thermocouple. That's now your thermocouple target.

Alternately, there are thermocouple plugs available. https://www.omega.com/pptst/TC-NPT.html

You can always go for wireless temp controller but you will be paying good money.

The plug suggested here is in my view the best and safest option, the pressure pot lid has one intake port that is not used and therefore plugged, this would be the ideal place for it.

My question to the OP is, how/what do you use to add or remove heat from the pot internally...?

Cheers
George

 

[eharri446]

One way to remove the heat would be to have the pot set in a pan to whic you could add ice and water to control the temperature,

 

[Dehn0045]

A thermowell is an option: http://a.co/d/3kom1Pt

You could make your own using tubing and fittings. I think most pressure pots have a threaded fitting on the inside of the cover that could be used.

 

[vtgaryw]

As a warning, it will increase the pressure inside the pot as the air expands when heated. I leave mine outside in our desert temps during the summer and the pressure has increased as much as 12psi. Granted, the extreme temp difference between the cold air from the compressor and our grueling heat is to blame, and your increase probably won't be nearly that much, but you may want to drop it a few psi when pressurizing until you know how much it will go up.

Are you talking about putting a heater in the pot, because I was only thinking about a TC to monitor the internal temp and toggle an external heating source on and off?

-gary

 

[vtgaryw]

A thermowell is an option: http://a.co/d/3kom1Pt

You could make your own using tubing and fittings. I think most pressure pots have a threaded fitting on the inside of the cover that could be used.

But I'd still have to find the right fitting to seal the TC wire off, correct?

-gary

 

[MRDucks2]

A thermowell is an option: http://a.co/d/3kom1Pt



You could make your own using tubing and fittings. I think most pressure pots have a threaded fitting on the inside of the cover that could be used.

But I'd still have to find the right fitting to seal the TC wire off, correct?



-gary

No. A thermal well is an enclosed tube you place the thermocouple in. You seal the well when threaded into the pot. Then you insert themocouple into the well, often with spacers to ensure it does not rest against the sides of the well.


Sent from my iPhone using Penturners.org mobile app

 

[Shock me]

If the temperature is being adjusted by an external water bath, I'd probably just monitor and regulate the temperature of the water bath and trust the laws of thermodynamics to handle the rest. If I really had to know the internal temperature of the pressure pot, I would cobble together a Raspberry Pi Zero with a temperature sensor and have it send data wirelessly to whatever them controls the water bath.

 

[TattooedTurner]

As a warning, it will increase the pressure inside the pot as the air expands when heated. I leave mine outside in our desert temps during the summer and the pressure has increased as much as 12psi. Granted, the extreme temp difference between the cold air from the compressor and our grueling heat is to blame, and your increase probably won't be nearly that much, but you may want to drop it a few psi when pressurizing until you know how much it will go up.

Are you talking about putting a heater in the pot, because I was only thinking about a TC to monitor the internal temp and toggle an external heating source on and off?

-gary

External heat will heat the air inside, which is cold from being compressed and will expand when heating up, thus increasing the pressure slightly. It *shouldn't* matter much, but if you're using external heat it's something to be aware of.

 

[bmachin]

Just out of curiosity. Why do you need a temperature controller?

Inquiring minds need to know!

Bill

 

[its_virgil]

My first thought also. I know it is cold in Vermont. I cast some snake blanks the other night here in N Texas. It was 34 degrees outside. After pouring and getting the molds into the pot I set the cup with the excess outside the shop door. Next morning it was cured. This has happened several times with different resins. So, I guess I don't understand.

Do a good turn daily!
Don

Just out of curiosity. Why do you need a temperature controller?

Inquiring minds need to know!

Bill

 

[frank123]

Any cheap PID controller and K type thermocouple should work fine as long as you only need to keep the temperature within a degree or so of the target temperature. More than that in accuracy starts getting expensive. The Chinese ones on eBay work fine, one intended for your temperature range would probably be better at low temp than one intended for several thousand degrees but any of them should work fine.

Be sure that you match the amperage draw of the heating elements to the relay in your controller or plan on using as separate SCR (also cheap on eBay) to make sure you don't overload anything (Ohms law and a simple volt meter makes this simple).

You could use nichrome wire for the heating element or more simply just use a salvaged ceramic heater heating element out of a ceramic space heater (new ones are cheap at Walmart and ones with a dead fan and good element are abundant as throw outs you can find for free if you look). One thing, if you use nichrome wire be fully aware that they are non insulated exposed live wire when heating and they have power on them, don't let them come in contact with anything conductive or they will electrify it and short your system out (or electrocute you if you happen to be the conductor they touch).

I think I'd just feed the thermocouple wires through the top gasket and use a bit of silicone sealer to make sure it worked the way I wanted before I'd be making anything special in the way of couplings to put the thermocouple through.

Watch some PID stuff on YouTube to get some ideas, everything from brewing equipment to kilns and heat treating ovens use them and DIY is a sort of popular thing.

 

[le_skieur]

I built a simple heat box for my presure pot it's warm with a 100w light bulb and control by a old mecanic thermostat. In order to watch the temperature indide, I use a wireless thermometer. It work very well at a cheap cost.

 

[chartle]

Already been thinking about this.

I think I researched this and the fitting is a 1/8" NPT fitting but I'm not sure how much pressure it can handle.

https://www.banggood.com/2M-EGT-K-T...ecToken=CgEwEAIaAklWIgJQRCgB&cur_warehouse=CN

For heat use one of these stuck on the outside on the bottom.

https://www.banggood.com/12V-200W-2...-p-1123501.html?rmmds=search&cur_warehouse=CN

And its all controlled with a PID

https://www.banggood.com/REX-C100-1...n=CgEwEAIaAkJUIgZGQlRfUEQoAQ&cur_warehouse=CN

I use the same PID and similar thermocoupler to control a 12 volt fan on my BBQ smoker.

Keeps the inside of my BBQ with one degree C.