Xtralis VESDA-E VEP-1P Quick start guide

DUCTS APPLICATION NOTE
February 2021
Doc. No. 35424_02

Ducts Application Note VESDA-E
35424_02 i
Preface
Xtralis has designed an air sampling smoke detection system specifically for use in ventilation ducts. The
information contained in this document will assist you when designing VESDA-E systems for this type of
application.
Note!
This system is not suitable for use in flexible ducts.
Related Products
VESDA-E VEP-1P and VEA detectors have been specially adapted for installation in ducts. Their model
numbers are VEP-A00-1P, VEA-040-A00 and VEA-040-A10.
Copyright©2021 Xtralis AG.

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Contents
1VESDA-E System Design......................................................................................................................1
Sampling Pipe Configuration in Small Ducts...........................................................................1
1.1.1 VESDA-E VEP-1P ...........................................................................................................1
1.1.2 VESDA-E VEA.................................................................................................................2
Sampling Pipe Configuration in Large Ducts...........................................................................3
1.2.1 VESDA-E VEP-1P ...........................................................................................................3
Key Design Considerations .......................................................................................................5
1.3.1 VESDA-E VEP-1P ...........................................................................................................5
1.3.2 VESDA-E VEA.................................................................................................................5
2VESDA-E System Installation...............................................................................................................6
Environmental Conditions .........................................................................................................6
2.1.1 VESDA-E VEP-1P ...........................................................................................................6
2.1.2 VESDA-E VEA.................................................................................................................7
Key Installation Considerations ................................................................................................7
3VESDA-E System Commissioning.......................................................................................................8
Hole Orientation Adjustment .....................................................................................................8
3.1.1 VESDA-E VEP-1P ...........................................................................................................8
System Performance Verification............................................................................................10
4System Maintenance...........................................................................................................................11
Local Codes & Standards.........................................................................................................11
First Year Requirements...........................................................................................................11
On-Board Filter Replacement ..................................................................................................11
Site Visit Requirements............................................................................................................11
Disclaimer On The Provision Of General System Design Recommendations........................................12

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1 VESDA-E System Design
Sampling Pipe Configuration in Small Ducts
1.1.1 VESDA-E VEP-1P
Small ducts are defined as those of width less than 1 m (3.28 ft). The figure below (Figure 1) shows a side
view of a duct section with the insertion positions for the VESDA-E VEP-1P detector inlet and exhaust pipes.
The detector inlet pipe should be installed in the middle of the duct at height H, where H is half of the duct
diameter. The detector exhaust pipe should be inserted approximately 0.5 m (1.64 ft) downstream of the inlet
pipe, at a quarter of the height of the duct.
Figure 1: Side view of the inlet and exhaust pipe
positions for a small ventilation duct.
A top view of the above installation is shown below (Figure 2). The number of inlet pipe sampling holes, their
required size and spacing are listed in Table 1. Both sampling pipe and exhaust pipe holes have the same
orientation with respect to the direction of the duct airflow.
Figure 2: Top view of the inlet and exhaust
pipe positions, including sampling hole location, for a small duct.
The sampling hole sizes, for the inlet pipe, are shown in Table 1. The exhaust pipe must have 4 × Ø10 mm
(13/32 inch) holes, regardless of the width of the duct. These holes should be located in the middle of the duct
width at least 50 mm (2 inches) from the side walls.

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Table 1: Sampling hole requirements for a VESDA-E VEP-1P detector with 5 m (16.4 ft.)
inlet pipe and 2 m (6.56 ft.) exhaust pipe in small ducts.
Duct width (m) {ft}
Number of Holes
Hole Ø (mm) {in}
Nominal Pipe Flow
Rate (L/min) {cfm}
0.3 {1.0}
2
6
{15/64}
40.8 {1.43}
0.5 {1.7}
3
5
{13/64}
44.2 {1.56}
0.7 {2.3}
4
4
{5/32}
38.6 {1.36}
0.9 {3.0}
5
4
{5/32}
46.4 {1.64}
Note!
Nominal sampling hole spacing is 0.2 m (0.66 ft.).
1.1.2 VESDA-E VEA
Return air sampling is achieved with microbore tubes for VEA system inserted in the return air duct behind the
exhaust grill. it is recommended the tubes are installed facing perpendicular to the duct airflow (Figure 3). A
specific sampling point, VSP-980-ST (No. 35295), must be used for VEA’s duct sampling. It can be mounted
on the duct by VEA Sampling Point Duct Bracket, part number VSP-1008.
Figure 3: Side view of the inlet tube position for a small ventilation duct
The detector inlet tube should be installed in the middle of the duct at height H, where H is half of the duct
diameter.

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Figure 4: Top view of the inlet tubes positions, including duct mounting
bracket for a small ventilation duct.
These sampling points should be located in the middle of the duct width at least 50 mm (2 inches) from the
side walls.
Note!
Nominal sampling point spacing is 0.2 m (0.66 ft.).
Sampling Pipe Configuration in Large Ducts
1.2.1 VESDA-E VEP-1P
Large ducts are defined as those with widths of 1 to 2 m (3.28 to 6.56 ft). For these ventilation ducts, it is
recommended that the inlet pipe of the smoke detector be in two branches. The figure below (Figure 5) shows
a side view of a duct section with the relative insertion points for the inlet and exhaust pipes. The two inlet
branches are located at a quarter of the height (H) of the duct with the exhaust pipe inserted mid-height
approximately 0.5 m (1.64 ft) downstream of the inlet pipes.
Figure 5: Side view of the inlet and exhaust
pipe positions for a large duct.
The following figure (Figure 6) shows a cross-section view of the same duct with the positions of the inlet
branches and exhaust pipe indicated. The number of inlet pipe sampling holes, recommended hole size and
spacing are presented in Table 2.

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Figure 6: Cross-section view of the inlet pipe
sampling hole setup and exhaust pipe in large ducts.
Table 2: Sampling hole requirements for a VESDA-E VEP-1P detector with 5 m (16.4 ft) inlet pipes
and 2 m (6.56 ft) exhaust pipe in a large duct.
Duct width (m) {ft}
Number of Holes
Hole Ø (mm) {in}
Nominal Pipe Flow
Rate (L/min) {cfm}
1.0 {3.3}
6
3.5
{9/64}
45.8 {1.62}
1.5 {5.0}
8
3.0
{1/8}
47.8 {1.69}
2.0 {6.5}
10
3.0
{1/8}
57.0 {2.01}
Note!
Nominal sampling hole spacing is 0.4 m (1.3 ft).
The exhaust pipe must have 4 × Ø10 mm (13/32 inch) sampling holes, regardless of the width of the duct.
These holes should be located in the middle of the duct width at least 50 mm (2 inches) from the side walls.
Note!
Calculations, performed with the ASPIRE pipe design software tool and
shown in Tables 1 and 2, apply to a 5 m (16.4 ft) inlet pipe and a 2 m (6.56 ft)
exhaust pipe. These calculations are suitable for an inlet pipe length of 1 to 10
m (3.28 to 32.8 ft) and an exhaust pipe length of < 2 m (6.56 ft), provided that
corresponding pipe flow rate adjustments are made. Always refer to local
codes and standards for hole size and spacing requirements.

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Key Design Considerations
1.3.1 VESDA-E VEP-1P
The following should be considered when designing a VESDA-E VEP-1P for duct protection:
•All inlet and exhaust pipes must be sealed at their far end with an end-cap.
•The holes on the inlet and exhaust pipes should be facing the airflow as shown in the above figures.
Holes with the same orientation eliminate unwanted flow faults associated with cyclical operation,
maintenance or power failure of the duct system. However, in some industrial applications, where the
quality of air inside the duct is poor, it is recommended that all holes on the inlet and exhaust pipes face
downstream, that is, 180° to the incoming airflow).
•The pipes should always be held in position at the duct walls with fittings such as rubber grommets.
Silicon is recommended, to ensure an airtight seal.
•Regardless of duct width, the exhaust pipe must have 4 × Ø10 mm (13/32 inches) holes.
•Never simultaneously sample from multiple ducts or ambient environments with the same the detector.
1.3.2 VESDA-E VEA
The following should be considered when designing a VESDA-E VEA for duct protection:
•Sampling points install in duct pressures within -30Pa to +30Pa.
•Maximum differential pressure (DP) of 30Pa between sampling points on same VEA unit.
•The exhaust of the VEA unit must be within a pressure range -30Pa to +30Pa.

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2 VESDA-E System Installation
Environmental Conditions
2.1.1 VESDA-E VEP-1P
You will need equipment to measure the following environmental conditions when installing a VESDA-E system
in a duct:
•Temperature.
•Humidity.
•Static Pressure – the pressure generated by the fan to deliver a specific flow-rate in the duct. This
pressure is a function of the flow-rate and impedance of the duct system.
•Air Pressure.
•In air-return ducts, the smoke detector must be installed where the static pressure is above −500 Pa
and the air velocity in the duct is below 20 m/s or, converted to volumetric flow rate (m3/hr) = velocity
× duct area.
•Always vent the exhaust pipe back into the ventilation duct, even when the duct pressure is sometimes
< 20 Pa, because the duct system operation may change in the future.
Condensation may occur when the dew point temperature of the air in the ventilation duct is at or above the
ambient temperature of the area where the smoke detector is installed. This usually occurs when the
temperature of the humid air in the duct is higher than the ambient temperature of the air outside the duct,
where the detector is to be installed, and the temperature of the air inside the sampling pipes of the detector.
You should measure the temperature and humidity both inside the duct and in the area where the detector will
be installed. If the results indicate that condensation may be a problem, refer to the ‘Duct Sampling and
Condensation’ section of the Pipe Network Installation Manual for advice on how to modify the design. The
Pipe Network Installation Manual (Document Number 10255) forms part of the VESDA-E System Design
Manual.
One solution for combating condensation is to mount the detector on its side (Figure 7). This places the laser
chamber higher than the aspirator so that any water in the inlet pipe does not reach the detector chamber.
Figure 7: VESDA-E VEP-1P detector sideways mounting
solution, to combat condensation.
The sampling pipe should be removed from the detector regularly for inspection, especially during winter, to
determine whether any condensation is forming inside the pipes.
Smoke tests should be conducted regularly during the first two months following installation. If the smoke tests
fail, condensation may have affected the air filter in the detector. Replace the air filter and re-test. The
condensation problem will need to be addressed by following the methods described above.

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If you have any doubts about the installation, seek support from your local Xtralis office or VESDA distributor.
2.1.2 VESDA-E VEA
Ensure duct environmental conditions do not lead to water condensation inside the tube.
Key Installation Considerations
You must consider the following when installing a VESDA-E system for duct protection:
•For air-return (negative pressure) ducts, smoke sampling must occur:
- Upstream and away from any fans.
- Upstream of humidifiers, heating coils and filters.
- Upstream of fresh air intakes.
•For a smoke detector mounted on the duct, ensure there are no tangible vibrations when the duct
system is in full operation. If there are vibrations, insert visco-elastic foam between the smoke detector’s
mounting bracket and the external surface of the duct.
•The inlet pipe/tube of the VESDA-E detector must be inserted at a distance of six to ten duct widths or
diameters from any flow disturbance caused by sharp bends, plenums, nozzles, branch connections
etc. Hence this system is not suitable for flexible ducts.
•Make sure that sampling holes/points are at least 50 mm (2 inches) away from the duct walls.