INSTALLATION AND MAINTENANCE OF DIESEL AND NATURAL GAS ENGINES BASIC AND TUTORIALS


The engine installation should be designed with maintenance requirements in mind. Serviceable components such as filters, fittings, and connections should be readily accessible to the engine operator. Routine engine maintenance will not be neglected if the operator has easy access to the engine.

Sufficient service space must be present on all sides of the engine to allow for removal of even the largest engine components. An overhead crane should be incorporated into the engine-room design to assist the mechanic-operator in removing heavy assemblies. Air-line connections will be necessary for air power tools, as will scaffolding for servicing the engine.

Ventilation
In engine-generator installations sufficient airflow must be provided into the engine room for ventilation and combustion air. It is also good practice to calculate the amount of heat transferred to the room air (i.e., engine and generator radiator heat, plus any other heat sources) to determine the temperature rise of the engine-room air.

In many cases it is necessary to increase the engine-room airflow to maintain reasonable operating temperatures.

The following are general rule of thumb values that assume the only radiating heat source in the engine room is the engine-generator set. For greater accuracy, an independent engineering study should be made covering the following points:

Cubic feet per minute of air required to limit air room temperature rise to 18°F (10°C), over normal ambient = 45 × kilowatt rating
Cubic feet per minute of combustion air required = 3.5 × kilowatt rating for diesel engines
Cubic feet per minute of combustion air required = 2.4 × kilowatt rating for gas engines

The total air requirement equals the sum of the cubic feet per minute of combustion air plus the cubic feet per minute required to limit the room temperature rise.

Other ventilation considerations are filters for sandy or dusty areas and louvered openings at both inlet and outlet air openings. The louvers can be motor-operated and temperaturecontrolled.

Cooling System
Potential problems with the engine cooling system can be avoided if the following considerations are incorporated into the design and installation of the cooling system. Excessive fittings, elbows, and connectors in the system piping will impede coolant flow. Use of fittings should be kept to a minimum.

An expansion-tank balance line should be incorporated into the cooling system, running to the suction side of the water pump.This balance line will maintain a net positive suction at the inlet of the pump and reduce the possibility of air locks and cavitational erosion.

All filters, fill points, and bleed cocks should be installed in an easy-to-reach location. Place the radiator away from a wall or any other obstruction that causes air recirculation or restricts airflow.These obstructions would also include any dirt source, vehicle travel path, air-conditioning units, or exhaust stacks and chimneys.

Remember that the radiator must bein a location where it can be cleaned and serviced. In installations where gaseous or LP fuels are used, keep all floor drains and service trenches out of the engine enclosure. LP and some constituents of natural gas can be heavier than air and will quickly flow into such low spots, creating a fire hazard.

Exhaust System
Plan the exhaust system so that the gases are expelled to a safe outside area, consistent with all local building and environmental codes. Do not discharge gases near windows, ventilation shafts, or air inlets.The exhaust outlet must be designed to keep out water, dust, and dirt. To avoid metal stress and turbocharger damage, support the exhaust system independently, keeping the weight of the piping off the engine.

Roller-type supports and flexible exhaust connections should be used to absorb thermal expansion. (If overhead cranes and hoists are used in the engine room, the exhaust-system piping may have to be supported from below.)

A condensate trap and drain should be designed into the exhaust system.The drain should be in an easy-to-reach location.

If the exhaust systems of more than one engine are to be connected to a common exhaust, the engine manufacturer should be consulted beforehand. Exhaust-system backflow (common in such connections) could result in an engine that is not running. Exhaust-system backpressure should be checked periodically. The backpressure must fall within the limits established by the engine manufacturer.

Air Induction
As with other engine systems, accessibility is the key to air-induction system maintenance.The filter element should be positioned so that it can be easily removed and replaced. The filter should always be positioned at the entrance to the air induction system; when combustion air is ducted in from outside the engine room, the filter should be at the opening to the piping.

All systems should be equipped with a restriction indicator to show excess pressure drop due to filter-element plugging.

Always locate the air inlet away from concentrations of dirt, exhaust stacks, fuel tanks, tank vents, and stockpiles of chemicals and industrial wastes. Try to duct air to the engine from a cool, dry, dirt-free area.The ambient temperature at the air inlet location should ideally be 60 to 90°F (15 to 32°C).

Run all air ducts away from engine exhaust pipes, heating lines, or other hot areas.Remember to allow clearance for overhead lifts and cranes when air ducts run through the engine room.

Air ducts should be thoroughly sealed to avoid drawing dirty air in behind the filter. The ducting must be checked periodically for leaks.

Air-system ducting should be seamless, welded-seam, or PVC piping. Flanged fittings with gaskets, not threaded connections, should be used between pipe sections to avoid restrictions in the system.

The best ducting system is as short and straight as possible, using long-radius bends and low-restriction fittings. Never allow air-duct restriction to exceed 2 in (50.8 mm) of water column. Air-ducting systems must be leak-free under vacuum conditions.

Engine Alignment
The alignment of the engine mount and the alignment between the engine and the driven equipment is critical to long engine life. Alignment should be checked periodically according to the manufacturer’s recommendations.

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