Kohler 20--2800 kW manual Flexible Connector, Gas Piping, Fuel Regulators

6.8 Flexible Connector

An approved flexible connector should always be used between stationary gas piping and the engine-mounted fuel system components. It should be at least six inches (15.3 cm) long or as recommended by the generator supplier based upon engine specifications.

6.9 Gas Piping

Gas piping should be Schedule 40 black iron pipe. Copper tubing may be used if the fuel does not contain hydrogen sulfide or other ingredients which will react chemically with copper. Fuel piping should never be used to ground electrical equipment. Piping should be sized according to the requirements of the equipment to be operated. Refer to the dimensional drawing for detailed information on your unit. In addition to the actual fuel consumption, the following factors must be considered:

DPressure loss due to length of pipe

DPressure loss due to other appliances on the same fuel supply

DPressure loss due to number of fittings

6.10 Fuel Regulators

Fuel regulators are compatible with both natural gas and LP gas. When used with natural gas the spring and retainer are installed. The spring and retainer are usually removed from the fuel regulator when used with LP gas. Refer to the appropriate generator set operation manual and/or decal on the unit for specific information regarding spring/retainer usage.

Gas fuels may require the fuel regulator to be mounted in a given position. The fuel regulator will function properly with the fuel regulator pointing downward for both natural gas and LP gas. The fuel regulator may be positioned so that it is pointing upward for use with natural gas only.

Two regulators are used in the typical gaseous fuel system:

DPrimary Regulator—This regulator provides initial control of the gas from the fuel supply. The primary regulator reduces line pressures to allowable inlet pressures for the secondary regulators on the system. This regulator would drop high pressure from a tank or transmission line to a low pressure, typically 4-6 ounces per square inch (1.7-2.6 kPa) or 7-11 inches (178-279 mm) of water column. This regulator is not usually supplied with the generator set, as conditions that dictate the type used vary depending on the method in which the fuel is supplied.

DSecondary Regulator—This low-pressure type regulator is mounted on the engine and is designed for a maximum inlet pressure of six ounces per square inch (2.6 kPa) or 11 inches (279 mm) of water column. The engine will operate satisfactorily at four ounces per square inch (1.7 kPa) or 7 inches (179 mm) of water column or less, but lower pressures may result in poor response to load changes or lack of power where the primary regulator is not near the engine.

Although regulators are designed to close and shut off fuel when the engine stops, a solenoid valve should be located ahead of the regulator and the flexible fuel connector to prevent the accumulation of an explosive mixture of gas and air, should either the flexible connection or regulator develop a leak. The generator set installer normally wires the solenoid valve to the engine starting controls so it will open (with battery power) when the engine cranks or runs.

Some fuel regulators have provisions to install a pressure gauge to test inlet and outlet pressures. If none are available, install pipe tees in the fuel line to serve this purpose and use pipe plugs on any unused openings.

32 Section 6 Fuel Systems TP-5700 7/93