While the number of gaseous extinguishing systems continues to grow, an often neglected aspect of the design is the enclosure integrity test.
With modern extinguishing agents the need to achieve and hold the specified concentration is critical and unless the integrity of the enclosure is tested it is possible, even likely, that the extinguishant will leak and the desired concentration wiil not be achieved.
In the construction stage of an enclosure it is a relatively simple and inexpensive matter to ensure that the required level of sealing is achieved while once the enclosure has been brought into use it may be impossible to correct any shortcomings.
An enclosure integrity test carried out during the construction stage will highlight any areas which need attention and when sealing has been completed a further test can be carried out to verify that the enclosure will retain the extinguishing agent.. On completion of the extinguishing system installation a further test can be carried out and the certification of the integrity tests will then form part of the commissioning documentation.
Integrity testing can be a valuable tool in the design and construction of generator enclosures. Typically these enclosures will be protected by a total flooding carbon dioxide system which will be test discharged on commissioning the enclosure.
If an integrity test is carried out prior to the test discharge the behavour of the enclosure can be predicted and any leaks can be rectified prior to carrying out a discharge test. The results of the discharge test can then be retained on file together with the results of the integrity test. If future integrity tests produce similar results it can be reasonably assumed that the CO2 system will continue to protect the enclosure.
Generator enclosures are subject to major penetrations in the course of routine maintenance and the removal of large sections of wall and roof are not uncommon to allow for the removal and replacement of sections of the generator set.
When the enclosure has been restored an integrity test should be carried out and the result compared to the original test this will establish that the enclosure has been correctly reinstated.
Another aspect of gaseous extinguishing systems which has come to prominance in recent years is the need for pressure relief. On discharge of the system the pressure in the enclosure will increase for a very brief period and unless this increase in pressure is allowed for in the construction of the enclosure serious structural damage may result.
We routinely test for this increase in pressure as part of our standard integrity test and will make recommendations regarding the need to fit pressure relief vents.