[Clayart] orifices

Vince Pitelka vpitelka at dtccom.net
Thu Oct 6 20:18:35 EDT 2016

Hi Bill - 
Natural gas and low-pressure propane are measured in WCI, and high-pressure propane is measured in PSI.  Our outdoor kilns (salt, soda, and a small gas downdraft test kiln) all have adjustable high-pressure propane regulators that read in PSI.  Our indoor downdraft and updraft gas kilns are all regulated down to 11 WCI and have WCI gauges between the valves and the orifices. 
- Vince 

Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpitelka at dtccom.net  

-----Original Message-----
From: Clayart [mailto:clayart-bounces at lists.clayartworld.com] On Behalf Of William Schran
Sent: Thursday, October 6, 2016 8:30 AM
To: Clayart international pottery discussion forum <clayart at lists.clayartworld.com>
Subject: Re: [Clayart] orifices

Propane gas pressure is measured in pounds per square inch, natural gas pressure is measured in water column inches.
The Geil kiln we had at school had a pressure gauge that had had marks for both so my students could see the relationship.
We fired with natural gas and I wanted 11 wci at the kiln, so had the gas contractor install a one pound meter, giving me about 27 wci, and used a regulator to bring it down to 11 wci.

Here¹s a link to Ward Burner¹s that addresses this:


Bill Schran
wschran at cox.net

On 10/6/16, 1:57 AM, "Clayart on behalf of sumi"
<clayart-bounces at lists.clayartworld.com on behalf of sumi at herwheel.com>

>I have 11 water column inches of propane. It is regulated to 11" at the 
>kiln. I generally turn it up no more than 5.5". But we are at high 
>altitude. Anyway, it seems to work with the natural gas orifices. And I 
>think what I have are tube burners, not venturis, from what Vince said.
>They sure are tube-shaped. (No flame retention tip I am pretty sure,
>though.) But it sounds like there isn't a lot of difference. I'm just 
>kind of wondering if that was part of my problem with oxidation on the 
>bottom, not enough turbulence.
>> if your pressure is low, and not a great flow of gas, you may need to 
>> increase the size of your orifice to match it.
>> we don't know what sumi has to her kiln. it may be low and the 
>> natural gas orifices may help make up the difference.
>> a quality heating expert can measure all the pressures. they have 
>> tools to do that.

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