Leakage testing of exhaust gas systems
Other topics from this section:Heating systems using low-temperature or condensing technology are generating fewer and fewer exhaust gas losses. The reduction of exhaust gas losses is linked to the reduction of the exhaust gas temperature. However, low flue gas temperatures can mean that the flue gases no longer have sufficient energy to escape through the chimney or flue gas line to the outside. To ensure that the heating system nevertheless works properly, the exhaust gases must be transported outside with the aid of blowers or fans. This creates an overpressure within the exhaust system. Any leaks in the exhaust pipes would therefore lead to toxic flue gases escaping into the room air. It is therefore advisable to carry out a leak test of the exhaust system.
The general requirements for the tightness of exhaust systems are described in DIN EN 1443.
PERFORMANCE OF THE LEAKAGE TEST OF EXHAUST SYSTEMS
DIN EN 1443 "Exhaust systems - General requirements" specifies limit values for the leak tightness of various types of exhaust systems. The following table lists some exhaust system types with their permissible leakage volume flows.
| Type of exhaust system | Class | Pressure | Allowable leakage rate per m² internal surface |
| Exhaust systems in negative pressure operation (chimney) | N1 | 40 Pa | 120 l/min (7,20 m3/h) |
| N2 | 20 Pa | 180 l/min (10,80 m3/h) | |
| Exhaust system with low overpressure (exhaust pipe) | P1 | 200 Pa | 0,36 l/min (0,0216 m3/h) |
| P2 | 200 Pa | 7,20 l/min (0,432 m3/h) | |
| Exhaust system with medium overpressure (exhaust pipe) | M1 | 1500 Pa | 0,36 l/min (0,0216 m3/h) |
| M2 | 1500 Pa | 7,20 l/min (0,432 m3/h) | |
| Exhaust systems in high-pressure operation (combined heat and power plant) | H1 | 5000 Pa | 0,36 l/min (0,0216 m3/h) |
| H2 | 5000 Pa | 7,20 l/min (0,432 m3/h) |
The necessary test pressure according to EN 1443 will be indicated depending on the selected installation class. Furthermore, the indicated volume flow will change automatically to the correspondent unit.
The Wöhler DP 600 will automatically start a self test to control the internal probes. The self test takes 10 sec. The test also checks if the exhaust gas system is at normal pressure and if there are any pressure variations.
After that the Wöhler DP 600 will automatically start the measurement and creates the test pressure. During the measurement the currently measured volume flow is indicated. As soon as the readings have stabilized, the Wöhler DP 600 will perform the measurement and finish the test after that.
Shape, length and diameter can be entered for three sections. The Wöhler DP 600 will calculate the cross section area automatically.
The measured leakage rate, the maximum allowed leakage rate according to EN 1443 and an evaluation (test passed or test not passed) will be displayed.
Summary:
- Ensuring that the exhaust system has been built in accordance with the specification and technical rules.
- The general requirements for the tightness of exhaust systems are described in DIN EN 1443.
- The leak test can be carried out with the Wöhler DP 600 on negative pressure, positive pressure and high pressure exhaust systems.
