TP-6727 10/11
22
Section 2 Open Units
Rain cap.
To prevent precipitation from entering the
exhaust pipe, install a rain cap on vertical outlets. See
Figure 2-11. In a climate where freezing is common, do
not use a rain cap. Instead, extend the exhaust piping at
least 610 mm (24 in.) beyond the roof line and create a
gradual U bend at the end to direct the exhaust outlet
downward. Keep the pipe outlet at least 457 mm (18 in.)
from the roof to prevent hot exhaust from igniting the roof
material.
Note:
Avoid using a rain cap in areas subject to freezing
temperatures.
5
8
1
2
3
4
9
7
6
10
11
15
12
13
14
TP-5700-5
6
1. Rain cap (or gradual U bend)
2. Rain shield
3. 254 mm (10 in.) minimum
4. 25 mm (1 in.) minimum
5. Exhaust pipe
6. Ventilation holes at both ends
7. 254 mm (10 in.) minimum
8. 25 mm (1 in.) minimum
9. Flashing
10. Inner sleeve
11. Outer sleeve
12. Thimble outer diameter
13. 254 mm (10 in.) minimum outside
14. 254 mm (10 in.) minimum inside
15. Exhaust pipe diameter
Figure 2-11
Double-Sleeved Thimbles and Rain Cap
2.3.6
Exhaust System Backpressure
Exhaust
backpressure
limits
engine
power
and
excessive
backpressure
causes
serious
engine
damage. Excessive backpressure usually results from
one or more of the following reasons:
D
The exhaust pipe diameter is too small.
D
The exhaust pipe is too long.
D
The exhaust system has too many sharp bends.
D
The exhaust silencer is too small.
D
The exhaust silencer is not the correct design for the
application.
The engine’s maximum exhaust backpressure limit is
10.2 kPa (3.0 in. Hg). Use the following procedure to
verify that the installed exhaust system does not exceed
the maximum exhaust backpressure limit.
Exhaust System Backpressure Calculation
Procedure
Determine the total backpressure by calculating the
effects of the individual exhaust system components
and adding the results. Make calculations using either
English or metric units. Exhaust pipe references are
nominal pipe NPT (in.) sizes. The procedure shows an
example with
italic
text.
1. Identify the type of silencer used in the application
and refer to Figure 2-12 for the silencer back
pressure.
Example: Determine the silencer backpressure for
the recommended critical silencer on a model
30kW generator set.
Silencer backpressure = 5.5 kPa (1.6 in. Hg)
2. Refer to Figure 2-12 for the backpressure from the
J-shaped engine-mounted exhaust pipe.
Example:
Determine
the
exhaust
pipe
backpressure for a model 30kW generator set.
Exhaust pipe backpressure = 1.7 kPa (0.5 in. Hg)
Silencer Type
Backpressure, kPa (in. Hg)
15kW
30kW
Residential, SIEO, 2 in. NPT
1.5 (0.47)
4.7 (1.4)
Critical, SIEO, 2 in. NPT
1.7 (0.51)
5.5 (1.6)
Exhaust J-tube
0.3 (0.1)
1.7 (0.5)
Figure 2-12
Silencer and Engine Exhaust Pipe Back
Pressures
Summary of Contents for 15REYG
Page 1: ...Commercial Generator Sets Models 15REYG 30REYG TP 6727 10 11c Installation...
Page 16: ...TP 6727 10 11 16 Section 1 General Notes...
Page 44: ...TP 6727 10 11 44 Section 5 Controller Notes...
Page 48: ...TP 6727 10 11 48 Section 6 Generator Reconnection Notes...
Page 64: ...TP 6727 10 11 64 Notes...
Page 65: ...TP 6727 10 11 65 Notes...
Page 66: ...TP 6727 10 11 66 Notes...
Page 67: ......