What happens when a kiln is used to fire ceramics?
Ceramics are made from clays and other materials which produce undesirable fumes during firing. The primary fume is carbon monoxide. This is produced during the oxidation of organic material. Fumes can also contain sulfur oxides, hydrogen flouride and volatilized metals. These fumes are unhealthy and should not be breathed. Because gases expand when heated, the fumes will not stay inside the kiln unless the kiln is kept under negative pressure. From a health and safety standpoint, it is important to remove fumes from the work area.
What are health issues associated with fumes and vapors?
OSHA has set standards for carbon monoxide exposure of 35 ppm for long term exposure and 200 ppm for short term exposure. Independent testing has shown that these fumes can reach over 400 ppm near the kiln during firing. Many hobbyist work in in rooms with unvented kilns complain of headaches, fatigue, sore throats and nausea. These are classic symptoms of carbon monoxide poisoning. When properly installed and operated, a downdraft vent removes all harmful fumes and helps provide a safer working (and living) environment for you and your family. The carbon monoxide level in your home and workroom can be measured using a device called a dosimeter tube, which records the level of exposure. It is an inexpensive device (about $25.00) that provides good information.
Are there any regulations for venting?
Some states and localities have set venting requirements for classrooms and workrooms. Your local and state health board should have this information. Even if your area doesn't have regulations, venting is still important. The Uniform Mechanical Code lists accepted venting methods. The downdraft system is listed in the 1992 approved Code.
What good does venting do?
Fume removal is the number one benefit of venting. The Orton system collects and contains the fumes so they can be removed from your work area to the outside - fumes never enter your home. An automatic vent also adds safety to firing. When manually venting, you need to prop and then close the lid of the kiln. The Orton vent eliminates this because the kiln stays closed. The kiln also cools faster with an automatic system like the Orton vent. In some cases, up to four hours faster. This means you can empty and refill the kiln in less time and complete the firing for your students in a timely matter.
For ceramic pieces, venting with the Orton system means color turns out bright and students can fire red glazes without disappointment. Fewer firings may be needed because you can mix different colored pieces in one load. Finally, venting extends the life of the metallic parts of the kiln by removing corrosive fumes. This means longer kiln life, better performance and reduced repair costs.
How about moving the kiln to a garage or shed?
Fume removal is still important. Without proper ventilation, harmful fumes can settle on windows, walls, and even your car or other equipment, causing etching and corrosion. Also, your firings will not be improved without the benefit of downdraft venting.
What kinds of vents are there?
Two methods of venting are typically used. Either vent the room or vent the kiln.
Venting the Room
When venting the room, fumes are allowed to escape from the kiln into the classroom or workroom. Using an exhaust system, room air is exchanged with fresh make-up air. Considerable make-up air is needed to adequately remove fumes.
Venting the Kiln
Two methods can be used to vent the kiln. A hood can be placed over the kiln, or a downdraft vent system can be used to keep the kiln under negative pressure. Gases are exhausted outside the building.
The downdraft venting method is superior to hoods because it removes all of the fumes and requires less make-up air. Fumes are not released into the classroom or workroom. The downdraft vent also improves firing conditions inside the kiln.
With a hood system, fumes are released into the classroom or workroom before they are collected. The effectiveness of the hood depends on how close it is to the kiln and the volume of air being removed from the room. Rarely does a hood remove more than 85% of the fumes. Make-up air of more than 250 CFM is required.
The downdraft system made by Orton and other manufacturers allows the kiln to remain closed throughout the firing. It also keeps the kiln under a slight negative pressure. This means all the fumes are exhausted and the air needed to fire the ceramics is brought into the kiln. The improved air flow also results in more uniform temperatures within the kiln, reducing hot and cold spots. The downdraft vent fits beneath or on the side of the kiln, saving space and mobility. In the US today, the downdraft vent is the standard for kiln venting.
What about installation?
Installation is as easy as venting a dryer. In many instances, you can install the vent yourself, with help from your spouse or a neighbor. Depending on the configuration of your house and the workroom, the vent can be exhausted to either an outside wall or a window, using standard dryer ducting.
Our technical staff can assist you with specific installation concerns and many ceramic supplies and kiln repair companies can do installations as well.
How much would it cost to buy the Orton vent and to run it?
We know budgets can be tight. That's one of the great things about the Orton vent. The cost for the vent is less than $400. That includes 8' of ducting and other parts needed for installation. The cost to run the vent is about 1 cent an hour. For an 8 hour firing, that's only 8 cents to fore safely and remove fumes. Compared to hood systems, the Orton vent can save $1.00 a day for the needed make-up air. Made of stainless steel and equipped with a heavy duty blower, the Orton system will provide many years of service under normal operating conditions.
How many downdraft vents are used in homes?
Thousands of Orton vents are used in homes, studios and schools nationwide today.