Raku high and low pressure systems

[Kirakat]

Hi,

 

I currently do smoke firings in an oil drum, fired with wood, but I would like more control over the temperatures reached. I’m thinking of building raku kiln from another drum and trying saggar firings.

 

One question I have is about regulators. I had always intended to use a high pressure regulator but have found it difficult to source an inexpensive change over regulator (I want to be able to connect two gas bottles up) for high pressure systems.

 

There seem to be plenty of change over regulators for low pressure systems, so I was wondering if it would make any difference if I went for a low pressure system instead.

 

I believe some people use low pressure systems for raku.

 

What are the differences between using high and low pressure systems? Is there a difference in the results, the time it takes and the cost?

 

Also, how many firings would you expect to get from a 5gk or 10kg gas bottle?

 

Thanks

 

Kirakat

[liambesaw]

So I tethered two tanks together with hosing and a T, and just used the needle valve on the weed burner as a regulator.  Worked great.  I guess that would qualify as high pressure.

Here is the manifold I bought to connect them

Mr. Heater 2-Tank Hook-Up Kit with Tee and 30-Inch Hose Assembly with P.O.L. Male Ends https://www.amazon.com/dp/B000K287CG/ref=cm_sw_r_cp_apa_i_9SwaDbJTWG2GK

May not be available in your country but not too complicated.

As far as how much gas, I went through about 15lbs for a bisque and a full 20lbs for a glaze firing and this was a 8cuft fiber kiln.  It will vary based on your kiln.  Also putting the tanks in a water bath will help keep them from freezing.

[Bill Kielb]

6 hours ago, Kirakat said:

Hi,

 

I currently do smoke firings in an oil drum, fired with wood, but I would like more control over the temperatures reached. I’m thinking of building raku kiln from another drum and trying saggar firings.

 

One question I have is about regulators. I had always intended to use a high pressure regulator but have found it difficult to source an inexpensive change over regulator (I want to be able to connect two gas bottles up) for high pressure systems.

 

There seem to be plenty of change over regulators for low pressure systems, so I was wondering if it would make any difference if I went for a low pressure system instead.

 

I believe some people use low pressure systems for raku.

 

What are the differences between using high and low pressure systems? Is there a difference in the results, the time it takes and the cost?

 

Also, how many firings would you expect to get from a 5gk or 10kg gas bottle?

 

Thanks

 

Kirakat

What do you consider high and low pressure? Low pressure natural gas is in the 7-11 inch range w.c.  (way less than 1 psi) Most propane sold in bottles are compressed to a  medium pressure. Low pressure natural gas uses larger orifices than medium pressure. Your burner choice usually dictates which pressure . A cubic foot of gas will combust and give off an amount of thermal energy. For natural gas it’s about 1000 btu, ( 300 w) ( per cubic foot and propane is about double that). So it comes down  how many cubic feet needed.  Most propane stuff like Liam’s weed burner are designed and sized for PSI pressure operation because that’s how  propane is most available here in the states.

A small Raku setup is probably 150,000 to 300,000 BTU and on two small propane bottles fires for 10 or more firings easily designed to operate from about 4 to 10 psi. (30-70 kpa)