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Escape Routes (New Features VentSim 5.0)


John Armstrong

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Refuge Bays and Escape Paths

Refuge bays can now be placed in the ventilation network and a new measure tool called “Escape Routes” can be used to calculate a route from any location in the ventilation network to the closest refuge bays or to the closest surface exits.

To place a refuge bay in an airway simply use the draw tool select “construct refuge bay” and click on the airway and a refuge bay will be displayed in that airway, to mark an airway as impassable go the airway and edit its properties, by clicking on the “no thoroughfare” option, the airway will then be excluded from escape routes calculation.

 5acab5c1c58cb_InsertRefugeBays.thumb.png.f8d6d49e84c820396da2330ffa4841b4.png

 

Using the measure tool “Escape Routes” (shown below) you can select any airway as the start of the route.

 

 5acab5c275308_SelectedEscapeRoutesTool.png.2ccaf022d7cda406a82759e253578496.png

 

VentSim DESIGN will calculate multiple routes to both the surface exits and to the closest refuge bays. Clicking on the bar chart will display each route in the model, and by using the model transparency setting you can easily make the path more visible. 
See picture below showing four paths to the closest and safest refuge bays.(note the refuge bays are the starting point are the selected airways)

 

5acab5bfabc2e_EscapeRouteDisplay.png.c3423f0557467d3a7569df3f35fc0321.png

 

The escape path includes some statistics about time required to walk and climb, it also includes time spent in travelling in smoke or contaminant areas, STEL
limits and other settings can be changed in the model settings. 


5acab5c054eba_EscapeRouteoptions.png.2c446fa167f2953e5ea482147af346a4.png

 

The No Thoroughfare and Refuge Bay options can be found in the edit properties on the fire simulation tab!

 image.thumb.png.6d1f8f8f9568e7504d04e38d95438984.png

 

 

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  • 1 month later...

John...

Again good work. This is going to be very helpful. I have tested it and found it works nicely Just a point here - I battled to find it but the help file pointed me in the right direction. The “no thoroughfare” option is located under the "VentFire" tab.

I really like the time estimate given. Very helful when one considers the duration of self-contained self-rescuers (SCSR's)

From settings perspective:

  • I think given that the average walking speed of a human being is in the order of 5km/h and that under an escape and rescue scenario (when people are escaping under duress likely while wearing a SACR under poor visibility), a more pessimistic escape speed of perhaps 3.0 to 3.5km/h should probably be aimed at in the "WalkRate" setting. Of course, the user can modify the speed preferences in the settings to their liking.
  • Not sure what the Australian STEL value for CO is but in South Africa that value is 100ppm. Will adjust on my end accordingly.
  • Could you provide more clarity on the climb rate? Is there some scientific basis for this number. It would be helpful to be able to define the number when asked by a client.
  • I also have no "feel" for what an appropriate "SmokeFactor" would be.
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Hi Shane,

Thanks for the feedback,

The climb rate is used when the gradient is greater than 50% the calculation is 350 metres of ascent per hour
The walk rate is used when the gradient is below 50% the calculation is the length of the distance / 6000 meters per hour + the height of the rise / 600 meters per hour

Also the smoke factor is used as a multiplier to represent a slower speed if walking through smoke

Both of these calculations come from discussion with Dr Rick Brake from Monash University (Australia)
There is also some other information that can be found in his Conference Paper · January 2013
"Fire modelling in underground mines using Ventsim Visual VentFIRE software"

 

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  • 2 weeks later...

John...

During this week's "Masterclass" in South Africa, Ralph McIntyre very kindly forwarded a paper (attached) with regard to this topic written by Wilfred Schreiber formerly of the CSIR. After discussing with Craig Stewart, I then committed to sharing this in this forum.

Wilfred did extensive work on the use of SCSR's and is considered an expert in the field. All testing of South African SCSR's in the industry was done by him and his team. The paper entitled "How to Calculate Safe Travelling Distances" describes maximum safe distances for escape routes whilst wearing a SCSR as well as the anticipated ventilatory demand when the SCSR is used in various mining conditions (very handy info).

So yeah – use it don’t use it – but I think this is at least a good technical guide to those who wish to design an Escape and Rescue strategy but would like some technical literature backup to support their strategy.

It is further worth noting, that with some exceptions, the 750m escape route is pretty much common practice here unless long duration SCSR’s are used.

SCSR-ESCAPE-CALCULATION.pdf

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