System Sensor Pipe Installation - Manual (Page 11)

User Guide: Aspirating Smoke Detector Pipe Installation
11
Sampling Methods
There are two general types of sampling methods: standard
pipe network sampling and capillary tube sampling. From these
sampling methods, several design configurations can be used
to meet the needs of a particular site environment. Local codes
and standards along with site requirements will help determine
the best air sampling method.
Standard Pipe Network Sampling
The following guidelines are used for any pipe network design.
Also, some additional guidelines specific to different sampling
methods may apply.
1. Local codes and standards always take precedence over
any values specified in this document.
2. Recommended pipe network material is nominal ¾"
schedule 40 internal diameter (25 mm OD) CPVC, PVC,
ABS or UPVC pipe.
3. Sharp bends decrease airflow and performance.
4. All pipe designs must have an end cap.
5. Multiple shorter pipes provide better performance than
a single longer pipe.
6. Symmetrical (Balanced) designs in pipe length, port size,
and port distribution are preferred to optimize FAAST
system performance.
Figure 11: Capillary tube sampling.
Figure 10: Sampling methods.
1.
2.
3.
4.
7. To prevent sampling ports form being blocked by dust
and dirt, taper and place the ports on the bottom side of the
sampling pipes, not on the top of the pipes. This ensures
that any falling debris does not clog the sampling ports.
8. To minimize the effect of pressure differentials, the sampled
air must be returned to the protected space wherever
possible. This eliminates any pressure differentials that
might reduce the air flow in the pipe network.
Capillary Tube Sampling
Capillary tube sampling is a method of locating sampling
ports remote from the main sampling pipe. This is particularly
useful where the main sampling pipe cannot be routed through
the area requiring protection for either technical or aesthetic
reasons. Capillary tubes are also used to sample equipment
cabinets or enclosures within the protected area.
In the absence of other guidance, it is recommended that a
minimum of two capillary sampling ports are sited in a room.
PipeIQ will allow sampling ports and capillary tubes to be added
as part of the design parameters. Local codes and standards
differ on issues, such as the minimum distance that detection
ports can be positioned from walls and ceilings. It is important
that the specific local regulatory requirements are observed.
The following guidelines are recommended for capillary tube use.
1. Try to keep the length of capillaries the same.
2. Capillary tube length should not exceed 26 ft. (8 m)
3. When sampling equipment cabinets or other enclosures,
the sampling port is typically placed at or close to the top of
the interior of the enclosure.
Frequently Asked Question – Can I paint the capillary port?
It is not recommended to paint the capillary port, but in certain
circumstances where aesthetics is a key feature, painting may
be allowed pending the approval of the local authority having
jurisdiction. If approved, the capillary port should be painted
and dried before the port is drilled. A sample port identification
label will be required to comply with NFPA.
Capillary Tube
Sampling Pipe
Tee Adaptor
Reducing Connector
Sampling Port Ceiling Tiles