Code Classroom
85% 20%
Facial coverage than other
Continued from page 18
eye/facewashes Better protection
er installation. Any testing should include the extreme conditions when scaling occurs and flue gas temps rise, near the end of the equipment’s service life. The Canadian standard, ULC S636, covers the design, construction and performance of gas venting systems intended for negative or positive pressure venting of gas- fired appliances producing flue gases having temperatures under the following: 1. Class I venting systems are suitable for gas-fired appliances producing flue gas temperatures of more than 135 C (275 F) but not more than 245 C (473 F); 2. Class II venting systems are suitable for gas-fired appliances producing flue gas temperatures of 135 C (275 F) or less; 3. Class II venting systems are further classified into
four temperature ratings as follows: (A) Up to and including 65 C (149 F) This temperature limit was intended to allow the use of
PVC pipe for use as a flue gas material. The temperature limit for PVC pipe is 140 F, and the allowable temperature in the ULC S636 standard exceeds the temperature limits set by PVC pipe manufacturers. (B) Up to and including 90 C (190 F) This temperature limit was intended to allow the use of
CPVC pipe for use as a flue gas material. The temperature in the pipe manufacturer technical data is 180 F. The ULC S636 standard allows the material to exceed the limit for CPVC piping by 10 degrees Fahrenheit. (C) Up to and including 110 C (230 F) This temperature limit was intended to allow the use of
Polypropylene (PP) pipe for use as a flue gas material. There is currently one manufacturer listed to this stan- dard, but the potential for the flue gases to exceed the 230 F is still there. A high-limit switch to shut off the boiler or water heater would be advisable. (D) Up to and including 135 C (275 F) I am not aware of any plastic pipe manufacturers that
meet this sub-section of the standard. The potential for the flue gas temperatures to exceed the 230 F is still there. A high-limit switch to shut off the boiler or water heater would be advisable. It will be interesting to see which way the industry goes
on this issue. There are forces pulling each way, and I believe that a significant change will be coming within the next few years. I hope the industry can develop a standard to allow low cost, high temperature plastic materials. I believe that we will see a few code changes on this topic in the next round of code hearings. The 2012 Code is near- ing completion and should be available in 2011. The 2015 code cycle will begin in the not too distant future.
Ron George is president of Plumb-Tech Design and Consulting Services LLC. He has served as chairman of the International Residential Plumbing & Mechanical Code Committee. Visit
www.Plumb-TechLLC.com, email
Ron@Plumb-TechLLC.com or phone 734/755-1908.
Circle 13 on Reader Reply Form on page 65 Page 20/Plumbing Engineer
The views and opinions expressed in this column are those of the author and do not reflect those of Plumbing Engineer nor its publisher, TMB Publishing.
May 2011
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