CAMERA GP 4889162 - Caterpillar

Flexible Connections
The exhaust piping must allow for movement and thermal expansion so that undue stresses are not imposed on the turbocharger structure or exhaust manifold. Never allow the engine exhaust elbow to support any external loads from any of the exhaust system components. At least one flexible joint or bellows must be installed between the engine exhaust elbow and the catalyst. Flexible connections are needed to isolate engine movement and vibration and to offset piping expansion and contraction.Piping Considerations
Avoid cantilevering loads off the end of the catalytic converter assembly. Be sure to consider the loads imposed to the catalytic converter from vertical exhaust stacks and exit piping. Never place more than 68 kg (150 lb) of unsupported piping or silencing equipment directly on the converter flanges. Anchor piping on one side of the converter only. Allow one side of the aftertreatment system room for thermal expansion. When lifting the catalytic converter, only use the ANSI flanges. The flanges are the only structural components of the converter body.Exhaust Backpressure
Backpressure effects the response of the engine to load changes, exhaust temperatures, and fuel consumption. Exhaust systems must be designed to provide the best compromise between noise and backpressure.The total exhaust backpressure of the CG137-12 packaged solution must not exceed the following:
Total back pressure 6.75 kPa (0.98 psi)
Maximum differential pressure across the catalyst 2.25 kPa (0.33 psi)
Illustration 10 g03403482
kPa equation
Illustration 11 g03403493
psi equationWhere:
P = Pressure drop (backpressure) measured in kPa and inches of water
psi = 0.0361 x in. of water column
kPa = 0.00981 x mm water column
L = Total equivalent length of pipe in feet or meters
Q = Exhaust gas flow in cubic feet per minute or cubic meter per minute at rated conditions
D = Inside diameter of pipe in inches or millimeter
S = Density of gas in pounds per cubic feet or kilogram per cubic meter
Ps = Pressure drop of silencer or rain cap measured in kPa or inches of waterUseful conversion factors:
psi = 0.0361 x inch of water column
psi = 0.00142 x millimeter of water column
psi = 0.491 x inch of mercury column
kPa = 0.0098 x millimeter of water column
kPa = 0.25 x inch of water
kPa = 3.386 x inch of mercury column
kPa = 0.145 psiUse the following equations to determine values of straight pipe equivalent length for smooth elbows
Illustration 12 g03403544
Standard elbow
Illustration 13 g03403546
Long sweep elbow
Illustration 14 g03403552
45 degree elbow
Illustration 15 g03403597
Square elbowWhere X = 1000 mm or 12 inchesAs shown by the equations, if 90 degree elbows are required, long radius elbows with a radius of 1.5 times the pipe diameter helps to lower resistance.Exhaust backpressure is measured as the engine is operating at rated speed and full load conditions. Use a water manometer or a pressure gauge to measure pressure at the NPT port in the inlet cone of the converter body.Catalyst Air Fuel Ratio Control Sensors and Wiring
The supplied catalyst and air fuel ratio control are tuned to maintain emissions compliance at or below 0.5g NOx and 1g NOx levels. The levels depend upon which catalyst is used. Ensure that the