BOCA Research and Evaluation Committee
1051 West Flossmoor Road
Country Club Hills, Illinois 60478-5795
Phone: 708/799-2305
KROY HEAT/AIR DUCTS
KROY INDUSTRIES, INC.
KROY INDUSTRIES/ALCAN PIPE DIV. OF ALCAN ALUMINUM CORPORATION
P.O. BOX 309
YORK, NEBRASKA 68467
PERFORMANCE OF PRODUCT FOR WHICH EVALUATION IS REQUESTED
PVC duct and fittings
MANUFACTURER'S INTENDED USE OF PRODUCT
The Kroy Industries Heat/Air Duct System utilizes polyvinyl chloride (PVC) tubing, Type SDR 81, for underground duct in heating and cooling ducting systems. Joints are joined with either PVC or approved metal duct couplings. The duct is available in sizes ranging from 4 inches through 24 inches.
PERFORMANCE OF PRODUCT FOR WHICH EVALUATION IS REQUESTED
PVC duct and fittings
MANUFACTURER'S INTENDED USE OF PRODUCT
The Kroy Industries Heat/Air Duct System utilizes polyvinyl chloride (PVC) tubing, Type SDR 81, for underground duct in heating and cooling ducting systems. Joints are joined with either PVC or approved metal duct couplings. The duct is available in sizes ranging from 4 inches through 24 inches.
Installation
Refer to typical PVC Heat/Air duct system installation sketch.
PVC ducts and fittings can be laid directly on earth surfaces. Unfilled gaps under the pipe shall be filled with backfill material. Pea gravel or aggregate (or the material taken from the trench, if equivalent) shall be used to backfill. The backfill material shall be spread evenly around the duct eliminating all gaps, and tamped in place.
Lengths of duct pipe are joined with either PVC couplings, or metal duct couplings. Metal duct couplings, and fittings shall have an approved protective coating. Joints should be secured with stainless steel screws and wrapped with PVC tape. PVC duct pipe and fittings shall be joined, utilizing an approved cleaner and solvent cement.
CODE ANALYSIS OF EVIDENCE SUBMITTED
The following data was submitted by the proponent for demonstration of compliance with the respective code sections listed above each item of evidence. The basis is the 1987 BOCA National Mechanical Code with the 1989 Supplement.
CODE SECTION: M-302.2
The BOCA Mechanical Code, Section M-302.2 requires nonmetallic duct to be constructed with Class 0 or Class 1 duct material in accordance with UL 181. Section M-108.4 provides for alternative materials and equipment since the provisions of this code are not intended to prevent the use of any material or method of construction not specifically prescribed by this code, provided any such alternative has been approved.
UL 181 similarly states in their Forward (Item D) "A product employing materials or having forms of construction differing from those detailed in the requirements of this standard may be examined and tested according to the intent of the requirements and, if found to be substantially equivalent, may be judged to comply with the standard."
Kroy Heat/Air Duct is limited in use to installation below finished floor which protects it from combustion. Therefore, the requirement of Class 0 or Class 1 duct material is not applicable. The UL 181 standard is specifically addressing the type of duct designed for use above ground.
Table 5.1 from UL 181 indicates the applicable tests for rigid fiberglass duct, and flexible duct. Tests considered to be applicable for underground rigid PVC air duct have been added.
UL 181 tests the strength of the non-metallic duct and duct material but does not address the testing of plastic duct or plastic material. ASTM 1784 and ASTM D2412 are the appropriate standards for the testing of plastic ducts for tensile strength, modulus of elasticity, flexural yield strength, impact strength, deflection temperatures, flammability, and chemical resistance.
EVIDENCE SUBMITTED
Report No. 89-0832 by Hauser Laboratories of Boulder, Colorado for Kroy Industries/Alcan Pipe. The test results determined that the representative samples of the products complied with the applicable tests of UL 181.
Report No. L/N 26938 on PVC Heat/Air Duct Pipe, Type SDR81 for Kroy Industries, Inc. was prepared by Applied Research Laboratories of Florida, Inc. The laboratory examination and tests determined that the representative samples of the products complied with ANSI/ASTM D1784, ASTM D2412, and ASAE S.376
CODE SECTION: M-302.3
The BOCA Mechanical Code, Section M-302.3 requires non-metallic duct to have an air flow friction coefficient similar to sheet metal.
Wind tunnel tests, in conformance with the criteria of the National Environmental Balancing Bureau, were performed to determine the air flow friction loss in the PVC pipe. The test results for PVC as compared to the friction loss for galvanized steel taken from a standard friction chart are as follows:
| Material |
Dia. Size |
Length |
Air Velocity |
Friction Loss |
| |
Inches |
Feet |
Feet/Min. |
Inches of Water/100 Ft. |
| PVC |
6 |
100 |
1800 |
0.6 |
| PVC |
8 |
100 |
1800 |
0.4 |
| Galv. Steel |
6 |
100 |
1800 |
0.9 |
| Galv. Steel |
8 |
100 |
1800 |
0.75 |
CODE SECTION: M-302.3
Installation in accordance with manufacturer's installation instructions.