AXLE GP-CENTER 1394700 - Caterpillar

TYPE="TABLE" @@@-->The radiator cooling system is designed to operate with a maximum duct restriction pressure of 127 Pa (0.5 inch of H2O). The inlet pressure is measured at a location in front of the fan (along the length of the engine) (5). The outlet pressure is measured at a location directly in front of the radiator outlet (4). In this way, the total pressure over the cooling pack (6) is measured. This measurement includes the restrictions encountered in drawing the air into the engine (7) and the restriction encountered in air exiting the engine room. When designing the engine room ventilation a pressure restriction target of 63.5 Pa (0.25 inch of H2O) should be aimed for, although lower is better.In order to measure the duct restriction of an installation, static pressure tubes (4) and (5) will be required. Use of any other means is likely to give inaccurate results. A water manometer (8) is normally sufficient for measuring the pressure. The static tubes should be aligned parallel with the air flow. A fine thread on a rod is a useful tool in identifying the direction of air flow over the engine. Care should be taken to keep rod away from rotating parts, including the fan. Illustrations 2 and 3 show typical locations of the static tubes used for taking pressure readings.Air Flow Measurements
An alternative to taking pressure measurements is to measure the air flow through the radiator. This can be done using an anemometer to measure the air velocity through an opening of known area, from which the volumetric flow can be calculated. As air density decreases with temperature, to get an accurate reading air flow measurements should be taken with the generator operating at no load. As the generator is operating at no load, there is minimum heating of the air flow.Anemometers are specifically available for ventilation and duct work, an instrument of this type should be used where possible. Measurements should be made where air flow is uniform, ideally just after the radiator outlet, but not after any louvers, bends or obstructions which could lead to non-uniform air velocities. An accurate measurement of volumetric flow is best made by taking at least 12 air velocity readings across the opening. It is best to draw up a grid with each cell being of equal area. Air velocity readings are then averaged, to give a total average air velocity through the opening. This is then multiplied by the opening area to give the volumetric air flow.
Illustration 4 g03730753
Typical exampleIllustration 4 shows the layout of the grid for calculating the volumetric flow.
Width (1)
Height (2)
Air flow (3) Technical Marketing Information (TMI) contains air flow data for the fans installed to generator sets along with the restriction curves for radiator cores. Overlaying the two curves will give the operating volumetric air flow at the curve intersection point. If the air flow is measured then the total pressure across the fan can be measured of the fan curve. Given the air flow reading,