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3. FLOW CHARACTERISTICS OF <br /> GAS PIPING SYSTEMS: <br />3.1. Elbows and Tees: Minimize the number of <br />elbows and tee fittings that increase pressure drop <br />and flow turbulence in the system. Where more than <br />three elbows and/or tees are required, use of swept <br />radius elbows (typical for welded pipe sections) will <br />help reduce pressure loss. <br />3.2. Reducing bushings (swages): Pipe reducing <br />bushings are the transition from a larger to smaller <br />pipe diameter or vice versa. Gas flow velocity is <br />slower in a larger diameter pipe compared to a <br />smaller diameter pipe moving the same volume of <br />gas. If a remote sensing regulator is used, it is <br />important to understand the dynamic pressure effects <br />caused by the gas flow velocities in different sized <br />pipe sections and design accordingly.6 <br />In some installations where it is impractical to run <br />approximately 10 feet of pipe, swaging up to a larger <br />diameter pipe is a practical method to increase the <br />gas volume between the service regulator and the <br />generator fuel system. For installations where this <br />method is used, an internally registered regulator is <br />strongly recommended. <br />3.3. Flexible fuel lines: Flexible fuel lines are <br />intended to isolate the rigid gas piping system from <br />vibrations on the generator set and must be installed <br />as straight as possible. They are not intended to <br />correct misaligned pipe sections or to serve as <br />an elbow. <br />3.4. Regulator vent lines: Regulator vents must <br />open downward and be screened to prevent insects <br />and water from entering the regulator case. Regulator <br />vent lines should be kept as short as possible to <br />reduce the possibility of affecting the regulator <br />response time. <br />4. DESIGN REQUIREMENTS: <br />4.1. Use Generac’s Power Design Pro7 gas pipe sizing <br />module to determine the minimum recommended <br />pipe size for the selected generator’s gas flow given <br />the anticipated length of the pipe run between the <br />service regulator and the generator fuel inlet, including <br />all elbows. Select the option to design for <0.5” water <br />column pressure drop. Refer to the Table 1 for more <br />detail. <br />4.2. The flexible fuel line shall be installed at the <br />generator fuel inlet located on the frame rail and must <br />exit the generator perpendicular to the frame rail. No <br />pipe fittings (elbows or swages) are permitted <br />between the flexible fuel line and the generator fuel <br />inlet port. <br />4.3. The flexible fuel line must be as straight as <br />possible. It is designed to isolate the rigid gas piping <br />system from vibrations on the generator set. It is not <br />intended to correct misaligned pipe sections or to <br />serve as an elbow. <br />4.4. Given the combined effects of pipe friction loss <br />and regulator droop, gas pressure should typically not <br />drop more than 2" w.c. from no-load running to <br />full-load running. Under no circumstances shall the <br />gas pressure measured at the test port on the inside <br />frame rail of the generator set drop below the <br />minimum rated gas pressure listed on the generator <br />nameplate. <br />4.5. Full-port ball valves, the same diameter as the <br />pipe which they are connected to, are to be used for <br />all shut-offs. <br />4.6. For multiple generator set installations (Generac <br />MPS), each generator set must have its own regulator <br />installed. Do not share a single large regulator across <br />multiple generator sets. <br />CONTINUED | 6 <br />Natural Gas Supply System Design Guide for Generac Industrial Spark Ignited Generators <br />Docusign Envelope ID: 2F58BEE5-DDBE-42EB-8DFA-5E2508488B04