Starting OR Firing the Small KK-8 Propane Furnace Kiln

Starting OR Firing the Small KK-8 Propane Furnace Kiln

Propane Melting FurnaceStep 1.  Place the kiln on a sturdy, level, fireproof surface. A minimum of 2’ x 3’ is necessary for the kiln, burner and pyrometer. The kiln is a modular design and comprised of three pieces; the base, the body and the lid. The body and lid are removable together or separately and allow for easy loading and removal of either small or large crucibles. When stacking, always align the clamps with the bolts in the same direction, as the stainless steel jacket is approximately 1/8” shorter than the width of the insulation. This allows for insulation to insulation contact of the components, when the kiln is stacked correctly. Remove the lid and place the 1” ceramic pedestal centered in the base portion of the kiln. The pedestal is where the crucible sits during the firing. The pedestal also helps to deflect the flame from the burner away from the crucible, thus preventing rapid thermal expansion from cracking the crucible due to direct contact of the flame. Insert the pyrometer probe into the side port until the probe protrudes into the interior of the kiln approximately ½”, then, set the temperature gage on your bench. Take care to prevent the wire connecting the temperature gauge to the probe from coming into contact with the exterior of the kiln.

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Step 2. Attach the 30 psi regulator and hose to a 5 gallon propane bottle and tighten snugly. Attach the end of the hose to the burner and leave it loose at this time. Align the burner with the port in the base of the kiln, with the needle valve of the burner facing up. Now, tighten the connection with the hose and the burner securely. Once the hose connection is tight, carefully insert the burner into the kiln, until the edge of the brass nozzle is flush with the short side of the angled burner port, then pull the burner tip back out of the port approximately ¼” to ½”.  Place the provided burner support under the brass nut on the hose where the burner attaches to the hose. The burner should be level and the burner tip should be approximately ¼” to ½” inside the port where the burner port enters the combustion chamber of the kiln, with the needle valve facing up.

Always use care when inserting or removing the burner from the kiln, as the insulation is soft and will become somewhat brittle after firing the kiln. Any degradation of the insulation in the burner port from repeated firings can be repaired with Liner Restore, provided with the kiln.

Step 3Once the burner is in place and the hose connections are tight, remove the lid from the kiln and prepare to light the burner. At the back of the burner are 4 holes that draw atmospheric oxygen into the burner during combustion. Place a flame from a ‘Bic’ style lighter, or a barbecue lighter, underneath one of the holes and crack the needle valve slightly. A chortling sound will be heard when the burner begins to light. Slowly open the needle valve, increasing the velocity of the propane gas flowing through the burner tube, until the combustion takes place inside of the kiln, the chortling sound stops and the burner is functioning properly. Occasionally, the burner can be difficult to light and you may have to open the valve up, close it rapidly, then open it up again rapidly, until the propane gas and atmospheric oxygen is properly flowing through the burner tube and the combustion is taking place inside of the kiln.

Another method of lighting the kiln is to take a long handled barbecue style lighter, reach inside of the kiln with the lighter and hold the flame in front of the burner port in the kiln. Slowly open the needle valve on the burner until the burner lights, then remove the lighter. If you attempt this method, make sure that you have a good pair of welding type gloves on. Things get seriously hot immediately, when the burner lights.

Once the burner is functioning properly and the kiln is lit, replace the lid on the kiln and turn the burner down until it is functioning properly without spitting or chortling, which is considered ‘idling’ and then observe the pyrometer temperature gauge. Remember that the kiln only requires approximately 30% to 35% of the burner’s capability to achieve 2100° to 2200° F. When the burner is in the idle mode, your pyrometer gauge will read approximately 1700° to 1800° F. Allow the temperature of the kiln to stabilize while in the ‘idle mode’, by observing the interior of your kiln through the lid port. Let the kiln to warm up until the complete interior of the kiln is a bright orange color and the pyrometer gauge reads in the 1700° to 1800° F. range. Once the kiln has stabilized, slowly raise the temperature to whatever suits your needs but remember; the burner is over-sized and small changes in the needle valve setting can raise the temperature markedly.