Fire Protection Systems and Controls

Reading Time: 11 minutes
Created with software version: 2022-1

1. Overview

This is the fifth tutorial in our PyroSim Fundamentals tutorial series, intended for new PyroSim users. In this tutorial, we will demonstrate how to model some basic fire protection systems in PyroSim. This tutorial will teach you the basics of the modeling tools provided by PyroSim, and NOT about the engineering methodology behind fire protection engineering. For that type of information, use resources like the SFPE Handbook of Fire Protection Engineering and your local code standards. We will also demonstrate how to configure your PyroSim model to react to it’s own state using Controls.

2. Before Starting

Before beginning this tutorial:

3. Introduction

Fire protection systems are combinations of equipment, such as fire suppression, alarm, and smoke control systems, used in tandem to protect a given space and it’s occupants against fires. These systems are often modeled in design fire scenarios to ensure compliance with code requirements, and more importantly, to ensure that they will perform their role in protecting occupants. Thankfully, PyroSim and FDS provide tools to model a wide array of fire protection systems, including sprinkler, smoke detector, alarm, and ventilation systems.

Additionally, PyroSim and FDS provide tools, called Controls, that allow you to configure your model to react to it’s own state changes. An example of this might be internal doors opening when an alarm system goes off, to model occupants opening doors to exit a building during a fire alarm.

We will model both a simple fire protection system and a simple Control in the model we have created in previous PyroSim Fundamentals tutorials.

4. Sprinklers

The first step in creating our fire protection system is to create a Sprinkler. Sprinklers in PyroSim are specialized Devices that will spawn water Particles to suppress a fire once their triggering condition is met. By default, Sprinklers are triggered by a Temperature Link. Temperature Links allow you to specify sprinkler properties provided by your sprinkler manufacturer in order to model your sprinkler as realistically as possible. FDS then uses these parameters in it’s Response Time Index algorithm to model sprinkler activation. Like other objects we have talked about before, you can create libraries of Temperature Links in order to easily re-use links across your projects.

We will use a default generic temperature link provided by PyroSim. These generic links are not meant to accurately model any specific sprinklers, and are only intended as examples of valid generic configurations.

4.1. Creating a Sprinkler

To create a Sprinkler in your model:

  1. Use the Devices > New Sprinkler action.
  2. In the Sprinkler dialog, change the name to Sprinkler, and set the Location to X=11.0m, Y=20.5m, Z=11.8872m.
  3. Leave the Activator set to Temperature Link, with the Generic Commercial Link selected in the dropdown.
  4. Click Ok to create the sprinkler.
pyro tutorial fundamentals add sprinkler
Figure 1. Creating the sprinkler.

This sprinkler will activate at the 68.33°C Activation Temperature set in the Generic Commercial Link, and disperse water droplets to suppress the fire in the model.

5. Vents

As described in the Your First Fire tutorial at the beginning of this series, Vents are 2D planes that allow us to apply a set of boundary conditions to cells in our model. In this tutorial, we will create a Vent to act as a rudimentary smoke control system. The geometry in this model does not represent mechanical ventilation space so the placement of this Vent will not be realistic, however it will showcase how to set up such a Vent using the tooling provided in PyroSim.

5.1. Creating a Vent

Before creating the Vent, we need to define the boundary conditions that we wish to apply. We do this by defining a Surface. To define this Surface:

  1. Open the Edit Surfaces dialog using the Model > Edit Surfaces action.
  2. Click New to open the New Surface dialog.
  3. Enter the name Exhaust, and set the Surface Type to Exhaust.
  4. In the Air Flow tab for the Exhaust surface, set the Specify Volume Flow field to \(10.0m^3/s\).
  5. Click OK to save the Surface.
pyro tutorial fundamentals exhaust surface
Figure 2. Creating the Surface for the Exhaust Vent.

The boundary conditions are now set up for use with the Vent. To create the Vent:

  1. Create a new Vent by using the Model > New Vent action.
  2. In the Vent Properties dialog, give the Vent and ID of Exhaust.
  3. Set the Surface dropdown to the Exhaust Surface you just created.
  4. Switch to the Geometry tab.
  5. In the Geometry tab, set the Plane to X, and set it to a value of 14.06m.
  6. Set Min Y to 21.0m.
  7. Set Max Y to 22.0m.
  8. Set Min Z to 11.3m.
  9. Set Max Z to 11.8m.
  10. Click OK to create the Vent.
pyro tutorial fundamentals fire protection create vent
Figure 3. Creating the Exhaust Vent.

The Vent you just created should appear on the wall next to the Door Obstruction. When active, this Vent will exhaust gas from the cells that it touches. However, in a real smoke control system, this Vent would not be active all the time. It would only activate when smoke was detected in the building. To replicate this behavior in our model, we will use Controls.

6. Controls

Controls, as their name implies, are used to control the state of various objects in your model. Most objects have a state that can be managed with a Control. In this example, we will create two Controls. One Control will activate the Exhaust Vent you created in the previous section, and the second Control will deactivate the Door obstruction in the model, simulating an occupant opening the door and evacuating the fire.

6.1. Creating Controls

We will first create a Control for the Exhaust vent. To create this Control:

  1. Open the Activation Controls dialog by using the Devices > Edit Activation Controls action.
  2. Click New to open the New Control dialog.
  3. Name the new control Exhaust Control and leave the Control Type set to Activation.
  4. Click OK to create the Control.
  5. With Exhaust Control selected, set the Input Type to Detector.
  6. Set the Action to Perform to Activate.

At this point the Control is created and ready to configure, however it currently does not control anything.

  1. In the text box of the Activation Controls dialog, click the first hyperlink to open a search widget.
  2. Search for "Exhaust", then click the checkbox next to the Exhaust Vent that you created in the previous section, then click OK.
  3. In the text box, click the second hyperlink, then click the checkbox next to the Smoke Detector Device, then click OK.
  4. In the text box, select the last hyperlink and set the delay time to 30.0s, then press Enter.
  5. Click OK to save the Control.
pyro tutorial fundamentals fire protection create control
Figure 4. Creating the Exhaust Control.

This Control now controls the Exhaust Vent. It will enable the Vent 30 seconds after the Smoke Detector reaches it’s smoke detection threshhold. After activation, the Vent will then provide a flow, defined in the Exhaust Surface definition, to exhaust smoke from the room.

One other use of Controls is to manipulate the geometry in your model to simulate things like doors opening/closing, or windows breaking due to heat. Let’s create another quick Control to remove the Door Obstruction 5 seconds after the Smoke Detector activates. To do this:

  1. Create another Activation Control named Door Control.
  2. Set the Control type to Detector, and the Action to Perform to Deactivate.
  3. Using the methods you learned from the Vent Control, configure the control so that it deactivates the Door Obstruction when Smoke Detector activates, delayed by 5.0s.
pyro tutorial fundamentals fire protection create control 2
Figure 5. Creating the Door Control.

Now, your model has another Control that will remove the Door Obstruction 5 seconds after the Smoke Detector activates, simulating a person opening the door to evacuate the room.

7. Results

The modeling of our simple Fire Protection System is now complete. The next step is to run the simulation and view the results.

7.1. Device and Control results

To run the simulation and view the results:

  1. Run the simulation using the pyro ui icon run Run icon.
  2. Once the simulation is finished, click the arrow next to the pyro ui icon plots Time History plots icon, and select Plot Device Results.
  3. Select the Sprinkler Device and view the chart.

As you can see in Figure 6, Sprinkler Devices record Temperature by default. As shown in the chart data, the Temperature continually rises until roughly t=30s, where it passes the default 68.33°C Activation Temperature of the Generic Commercial Link Sprinkler Link Model. At that point, we can assume that the Sprinkler activates to suppress the fire (we will verify the exact time later).

pyro tutorial fundamentals sprinkler results chart
Figure 6. Time History Plot of the Sprinkler Device.
  1. Close the Time History Plots window, then click the arrow next to the pyro ui icon plots Time History plots icon, and select Plot Control Results.
  2. Select the Exhaust Control Control and view the Chart.

As you can see in Figure 7, Controls provide data in terms of their activation status. A value of -1 indicates not activated, and a value of 1 indicates activated (please see the NOTE section below for a little more information on this). With this information, it appears that the Exhaust Control activates at around 37 seconds in to the simulation. Given that we configured this Control to activate 30 seconds after the Smoke Detector, we can extrapolate that the Smoke Detector activated at approximately 7 seconds. Again, we will verify the exact activation times later, but this appears to show that our simulation behaved as expected.

pyro tutorial fundamentals exhaust control results
Figure 7. Time History Plot of the Exhaust Control Control
  1. Select the Door Control Control and view the Chart.

The Door Control also appears to have behaved as expected. From Figure 8, you can see that the Control appears to have activated at roughly 12 seconds. Given that it was set on a 5 second delay following the activation of the Smoke Detector Device, it appears again that the Smoke Detector activated at approximately 7 seconds.

pyro tutorial fundamentals door control results
Figure 8. Time History Plot of the Door Control Control
  1. Close the Time History Plots window, then use the Analysis > Open Results Folder action.
  2. In the Windows Explorer, double-click the fire_protection_systems.out file to open it in Windows Notepad.
  3. Scroll to the bottom of the file, to the sections labeled DEVICE Activation Times and CONTROL Activation Times.

Figure 9 shows the exact activation times of the Devices and Controls in the model. As you can see, the Sprinkler Device activated at t=30.4s, the Smoke Detector Device at t=7.3s, the Door Control Control at t=12.3s, and the Exhaust Control Control at t=37.3s. All those values are exactly as expected.

pyro tutorial fundamentals control activation times
Figure 9. Screenshot of the .out file showing the activation times of Devices and Controls in the model.

7.2. 3D Control results

The next thing to do is view these results in 3D. To do this:

  1. Open the PyroSim Results viewer by clicking Show Results in the Run Simulation dialog, or by clicking the pyro ui icon results View Results icon.
  2. Use the View > Floor Settings action to open the Floor Settings dialog.
  3. In the Floor Visibility dropdown, select 9.144, or Floor 9.1. This is elevation of Level 4 as defined in the PyroSim preprocessor, just represented in meters.
  4. Locate the room of interest by panning and rotating the camera.
  5. Press the results ui icon play Play icon to begin the results playback.

With no results visualization selected, as is the default when opening the Results Viewer, the playback will show any geometry changes that take place in your model. As you can see in Figure 10, the Door Obstruction is deactivated, and the Exhaust Vent is activated at the proper times. Playback stops after the last geometric event in the model, which in this case is the activation of the Exhaust Vent at t=37.4s.

pyro tutorial fundamentals fire protection control playback
Figure 10. Playback showing the activation of Controls in the model.

Now let’s see the full playback of the model.

  1. Double-click the 3D Smoke and the Particles visualizations to enable them in the 3D playback window.
  2. Press the results ui icon play Play icon to begin the results playback.

As you can see in Figure 11, the fire protection systems and controls in our model work as expected. Shortly after the fire begins, the smoke detector activates, which triggers the opening of the door, simulating the evacuation of the occupant. Once the fire heats the sprinkler to 68.33°C, the sprinkler is activated and begins dispersing water to help suppress the fire. And lastly, 30 seconds after the smoke detector activated, the Exhaust vent is activated, helping to remove a large amount of smoke from the room.

pyro tutorial fundamentals fire protection full playback
Figure 11. Full playback showing all of the results of the model.

8. Conclusion

You should now be familiar with how you can model Fire Protection Systems and Controls in PyroSim. These systems can obviously get much more complex than the simple one demonstarted here, so it is a good idea to test your systems in small, discrete, fast-to-run simulations before trying them in larger ones. It will save you a lot of time and frustration, and will help ensure that your full model behaves as expected.

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9. Bibliography