The completed system shall be reviewed and tested by qualified personnel to meet the approval of the authority. Only equipment and devices designed to national standards shall be used in the system. To determine that the system has been properly installed and will function as specified, the following tests shall be performed.
Enclosure check
Determine that the protected enclosure is in general conformance with the plans.
Review of mechanical components
The piping distribution system shall be inspected to determine that it is in compliance with the design and installation documents. Nozzles and pipe size and, if appropriate, pressure-reducing devices, shall be in accordance with system drawings. The means of pipe size reduction and attitudes of tees shall be checked for conformance to the design. Piping joints, discharge nozzles and piping supports shall be securely fastened to prevent unacceptable vertical or lateral movement during discharge. Discharge nozzles shall be installed in such a manner that piping cannot become detached during discharge.
During assembly, the piping distribution systems shall be inspected internally to detect the possibility of any oil or particulate matter which could soil the hazard area or affect the extinguishant distribution due to a reduction in the effective nozzle orifice area.
The discharge nozzles shall be oriented in such a manner that optimum extinguishant dispersal can be effected. If nozzle deflectors are installed, they shall be positioned to obtain the maximum benefit.
The discharge nozzles, piping, and mounting brackets shall be installed in such a manner that they will not potentially cause injury to personnel. Extinguishant shall not directly impinge on areas where personnel may be found in the normal work area or on any loose objects or shelves, cabinet tops or similar surfaces where loose objects could be present and become missiles.
All extinguishant storage containers shall be properly located in accordance with 'approved for construction' set of system drawings. All containers and mounting brackets shall be securely fastened in accordance with the manufacturer's requirements.
A discharge test for extinguishants is generally not recommended. However, if a discharge test is to be conducted, the mass of extinguishant shall be determined by weighing or other approved methods. Concentration measurements should be made at a minimum of three points, one at the highest hazard level.
Other assessment methods may normally be used to reduce necessary discharge into the environment, for example, the door fan pressurisation test. However, a discharge test may be conducted if acceptable to the authority.
An adequate quantity of extinguishant to produce the desired specified concentration shall be provided. The actual enclosure volumes shall be checked against those indicated on the system drawings to ensure the proper quantity of extinguishant. Fan rundown and damper closure time shall be taken into consideration.
Unless the total piping contains not more than one change in direction fitting between the storage container and the discharge nozzle, and unless all piping has been physically checked for tightness, the following tests shall be carried out.
1. All open-ended piping shall be pneumatically tested in a closed circuit for a period of 10 min at 3 bar. At the end of 10 min, the pressure drop shall not exceed 20% of the test pressure.
2. All closed-section pipework shall be hydrostatically tested to a minimum of 1,5 times the maximum working pressure for 2 min during which there shall be no leakage. On completion of the test, the pipework shall be purged to remove moisture.
It is recommended that hydrostatic testing be carried out at the manufacturer's works where practicable.
It is important to note that pneumatic pressure testing creates a potential risk injury to personnel in the area, as a result of airborne projectiles if rupture of the piping system occurs. Prior to conducting the pneumatic pressure test, the protected area shall be evacuated and appropriate safeguards shall be provided for test personnel.
A test using nitrogen, or a suitable alternative, shall be performed on the piping network to verify that flow is continuous and that the piping and nozzles are unobstructed.
To be continued in the next issue.
For further details contact the FDIA on tel: (011) 397 1618.
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