Publicidad
Idiomas disponibles
Idiomas disponibles
APPENDIX A - PipeIQ and PIPE SYSTEM DESIGN
USING PipeIQ for SYSTEM DESIGN
PipeIQ is a design application to help a user create EN54 compliant
pipe layouts. Generating a suitable working design will require some
thought and understanding of the interacting variables in an aspirating
system.
The following methodology can assist when trying to design a pipe
network using PipeIQ. By following this sequence of steps, it should
be possible to arrive at an acceptable design (assuming one exists)
that has adequate air flow and hole sensitivity to operate within the
overall limits of the aspirating device. (See Pipe Design Methodology
Flow Chart.)
Suggested Design Methodology
1. Start a project in PipeIQ, choose the detector type, select the
required constraints option and the aspirating class and follow the
instructions to add a detector and create a representation of the
physical pipe layout.
To optimise the design:
2. In the Manage Pipe – Edit Properties window, set the number
of sample holes and hole spacing in the pipe network to comply
with local fire regulations and the EN54 approved figures. The hole
diameters can also be set in this window, or changed later. To end,
click Update Holes and then OK.
3. In the Design tab, click on the Calculations button; the Calculation
window will appear. Set the sample hole diameters and fan speed
to get the flow in the detector close to 45l/min.
4. Repeat step (3) above to eliminate any red boxes (out-of-range
sensitivity, transport time etc.)
5. Check the flow balance is ≥0.5. Using the auto-balance button will
probably create multiple sample hole diameters along the pipe;
avoid using this button if a single hole size is required. Be aware
that the auto-balance function may also reduce the pipe air flow,
ensure this is set back close to 45l/min.
6. Repeat from step (3), adjust hole diameters and fan speed to
achieve all the above figures.
7. Next, check that the sample hole sensitivity is practical for the
chosen class, i.e. it is not too sensitive. Ideally, to avoid false
alarms, hole sensitivity for a class C system should be 1%/m or
greater and certainly >0.5%/m.
8. If necessary, change the Alarm level to reduce the sample hole
sensitivity. The detector sensitivity is set from the Configuration
tab.
9. Repeat from step (3) to finalise the pipe design and save.
Tips to achieve an adequate design
Maintain the air flow in a FAAST LT-200 unit at, or around, its optimum
setting of 45 l/min. Increase/decrease hole diameters and fan speed
to achieve this.
Fewer holes in a pipe will tend to increase the sample hole sensitivity.
Adding extra holes close together may mathematically appear to
reduce the hole sensitivity, but in practical terms the system sensitivity
will remain high. Change the alarm level to raise or lower the sensitivity
of the sample holes.
Changing the hole diameter will affect the hole sensitivity and the
hole balance. Smaller holes may improve the balance but will reduce
the overall flow. Ensure this remains as close to 45l/min as possible.
It is recommended that the flow balance is not less than 0.5 for an
acceptable design.
Longer pipes will obviously have longer transport times; they also tend
to reduce the air flow, which further extends the transport time. Rather
than using one long single pipe, the use of a 'T' tap or two pipes per
channel can reduce long pipe runs and reduce the transport time. It
also helps with maintaining the air flow speed at the optimal level, since
N200-102-01
Pipe Design Methodology Flow Chart
PIPE DESIGN METHODOLOGY FLOW CHART
Review pipe
layout
N
Y
Is a design
possible?
??
it is equivalent to increasing the pipe diameter to the aspirating device;
but beware the flow does not get too high. In twin pipe systems it may
be necessary to reduce hole sizes, compared with a single pipe, to
achieve optimal flow. Alternatively, the fan speed can also be reduced,
but both these actions will increase the transport time.
Use of the Auto-balance button in PipeIQ will probably give the holes in
the pipe design a variety of different diameters. If one size of hole in the
sample pipe is desirable (for simpler installation and commissioning)
do not use this button. Pipes with equal size sample holes are also
easier to test – the farthest end sample hole will be the least sensitive.
11
Start Project
and create
pipe layout
Set number of
holes and hole
spacing
Set sample hole
diameters and fan
speed
Are the
N
parameters in
range?
Y
N
Is air flow
c.45l/min?
Y
N
Is the flow
balance ≥ 0.5?
Y
N
Is hole
Change alarm
sensitivity OK
level
for class?
Y
Save design
I56-6577-008
Publicidad
