The radiator discharge and the engine exhaust air must be routed outside of the generator room. It is encouraged to install the ductwork from the radiator outlet flange to the exhaust vent opening in a manner that prevents any recirculation of exhaust air back to the generator area. When required, the extended exhaust ductwork should be designed with as few bends as possible. When bends are necessary, they should be in the form of gradual sweeps to allow airflow with minimum restriction.

Flanged exhaust pipes, rated for at least 1500° F, are to be used and constructed of schedule 40 black iron, steel, or other suitable materials having adequate strength and durability. Using a flex joint between the engine connection point and the rigid piping is encouraged. In addition, it is recommended to use a flexible exhaust bellows to allow for linear and/or axial movement of rigid piping due to thermal expansion/contraction.

If used, Generac open units are shipped with the loose catalytic converter for onsite installation. For such units, use the generator specific installation drawing to properly locate the oxygen (O2) sensor for the emissions monitoring system. If the O2 sensor and catalyst are not correctly installed, the emissions system will not work properly and the unit may not comply with its EPA certification. Such conditions may also lead to engine damage. The catalytic converter and the silencer must be externally supported and should not be supported off the engine. The exhaust piping can be extended to route the exhaust to the desired location however, the exhaust backpressure must be calculated and the piping must be sized to keep the exhaust back pressure at the engine acceptable range.

Do not install blankets on the exhaust manifolds, turbocharger housings or other engine components. The use of manifold blankets can result in their premature failure. The shore power circuit, which is required to power up the generator auxiliaries, should be properly designed to accommodate the power requirement of all the available auxiliary equipment of the generator. The generator must be properly grounded and the wire carrying AC power should be separated from the DC wires. In addition, the communication wires should be routed in a separate conduit as well.

SPARK IGNITED GENERATOR FUEL PIPING REQUIREMENTS

The fuel line should be free of leaks and adequate ventilation is essential. The fuel supply must accommodate for fuel consumption rates at 100% load. The supply pressure and volume must meet the requirements described in the unit submittal packet, if specifications are not met, the generator will not operate properly and will probably display symptoms, such as hard starting, rough running, inability to carry a load, and erratic operation.

A primary regulator must be installed between the utility gas supply line and the generator gas inlet port. It is recommended to allow a minimum of 10 feet between the primary regulator and the generator. The regulator should be designed at 1.5 x greater than the 100 percent required fuel flow rating of the gen-set. Calculations should be made using a specific gravity of .65 for NG and 1.6 for LPG-V. The required fuel pressure to the unit should be measured at the factory-provided gen-set test port, prior to the startup. The pressure when the unit is cranking and the pressure while the unit is running at full rated load (kW) should be equal or less than 2 in. w.c below the static pressure. Black Iron piping is used for NG and LPG-V fuels. When installing LPG-L, the industry standard is copper pipe.

A stainless steel braid flexible hose (flex hose) between the generator connection point and the rigid black iron supply piping is also required. The flex hose shall be directly connected to the fuel connection inlet at the generator rail without any pipe fittings installed between the flex hose connector end and the generator connection point. The flex hose needs to be installed in a straight-line perpendicular to the generator set rail with no kinks or bends. The supplied flexible hose is not to be installed underground or in contact with the ground. It should be connected between the rigid supply piping and the connection fitting on the base of the generator set. Local fuel code may vary widely, please consult your local Generac dealer for more details.

CONCLUSION

These installation guidelines are intended to help customers become acquainted with the general requirements for optimal operation of their engine generator set. For more information about these concepts or the variety of Generac products available, contact your Wolter Power System’s consultant.

AUTHOR BACKGROUND

Muhammad Armaghan is a Product Manager at Generac Power Systems. He is responsible for the Industrial Generator product line. Armaghan has experience working in industrial power generation markets and has supervised several multimillion-dollar projects throughout the United States. These include power plants, healthcare facilities, data centers, and municipal projects. Armaghan has also worked closely with consulting and specifying engineers, as well as general and electrical contractors and end-users.