Requirements for setting sampling tubes and sampling holes for suction smoke fire detectors


In addition to the detection part, the main component of the suction smoke fire detector installed in large space is the sampling part, and the sampling part needs to be mastered in two aspects: sampling tube and sampling hole setting.So for the installation and construction, what requirements should be followed when setting the sampling tube and sampling hole of the suction smoke fire detector?Today will be detailed with you to analyze the answer.In the specification of “Code for Design, Construction and Acceptance of Aspirated Smoke Fire Detection and Alarm System”
In DB11/1026-2013, No. 3.4 design Requirements includes the setting requirements for sampling tubes and sampling holes of air-breathing smoke fire detector, including the following points: 3.4.5 The cross-section direction of sampling holes should be perpendicular to the direction of airflow and smoke movement.3.4.6 There should be no less than 2 sampling holes in a separate room.3.4.7 The total length of the sample tube of one detector should not exceed 200m, and the single tube length should not exceed 100m.The total number of sampling holes should not exceed 100, and the number of sampling holes on a single pipe should not exceed 25.3.4.8
When the outer diameter of the sampling head for non-metallic materials is 25mm, its inner diameter should be 21mm;When the outer diameter of non-metallic material walking stick sampling tube is 16mm, its inner diameter should be 14mm;The inner diameter of capillary sampling tube should be 5mm, and the maximum length should not exceed 4m.3.4.9 Refractory materials should be selected for the sampling tube and its accessories of the system, such as capillary sampling head, elbow, sampling tube connector, tee, end cap and sampling branch pipe.3.4.10
The minimum aperture of the sampling hole should not be less than 2.5mm, the maximum should not be more than 5mm, each sampling hole should be clearly marked (except for places with special requirements), the size of the sampling hole should be provided by the detector manufacturer.3.4.11 in standard sampling mode, end caps should have end holes with a diameter of 3 mm to 6mm.In return air sampling mode, the end cap does not need to be perforated.3.4.12 Sampling pipes may be arranged horizontally or vertically.The sampling pipe that passes through the structural beam and is laid in the space of the grid should be fixed at the bottom of the beam or on the grid.3.4.13 when the sampling pipe is arranged vertically, a sampling hole shall be set up every 2℃ temperature difference or 3m interval.In summary, the above content is the requirement given in the specification. Before the installation and construction of the suction smoke fire detector, we need to be clear first, so as to effectively avoid rework.

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