Suppression Systems¶

Model fire sprinklers, water mist, spray nozzles, and other suppression systems in FDS.

Overview¶

PyFDS provides comprehensive support for modeling suppression systems including: - Automatic sprinklers (quick-response, standard-response, ESFR) - Water mist systems - Spray nozzles - Gaseous suppression - Device activation and control logic

Components¶

A complete sprinkler system requires three components:

PART - Water droplet particle definition
PROP - Sprinkler/detector activation properties
SURF - Spray pattern and droplet generation
DEVC - Device placement and control logic (optional)

Quick-Response Sprinkler Example¶

Complete working example:

from pyfds.builders import PartBuilder, PropBuilder, SurfBuilder, DevcBuilder
from pyfds.core.geometry import Point3D

# 1. Define water droplet particle
water = (
    PartBuilder("WATER_DROP")
    .as_water_droplet(diameter=0.001)
    .with_color("BLUE")
    .build()
)

# 2. Define sprinkler property (68°C, RTI=50)
sprinkler_prop = PropBuilder.quick_response_sprinkler(id="QR_SPRINKLER")

# 3. Create sprinkler spray surface
sprinkler_surf = (
    SurfBuilder("SPRINKLER_SPRAY")
    .as_sprinkler(
        part_id="WATER_DROP",
        mass_flux=0.02,          # kg/s/m²
        median_diameter=0.001,   # 1mm median droplet
        velocity=6.0             # 6 m/s downward
    )
    .build()
)

# 4. Create device with activation control
sprinkler_device = (
    DevcBuilder("SPRINK1")
    .with_quantity("SPRINKLER_LINK_TEMPERATURE")
    .with_control(setpoint=68.0, trip_direction=1, latch=True, delay=2.0)
    .at_point(Point3D.of(3.0, 2.0, 2.8))
    .with_prop("QR_SPRINKLER")
    .build()
)

# Add to simulation
sim.add(water)
sim.add(sprinkler_prop)
sim.add(sprinkler_surf)
sim.add(sprinkler_device)

Sprinkler Properties¶

Predefined Sprinklers¶

# Quick-response residential (68°C, RTI=50, 60 L/min)
qr = PropBuilder.quick_response_sprinkler()

# Standard-response commercial (74°C, RTI=100, K=80)
sr = PropBuilder.standard_response_sprinkler()

Custom Sprinkler¶

# Early Suppression Fast Response (ESFR)
esfr = PropBuilder.sprinkler(
    id="ESFR",
    activation_temp=74,      # °C
    rti=50,                  # (m·s)^0.5
    k_factor=200,            # (L/min)/bar^0.5
    spray_angle=(45, 90),    # degrees
    pressure=200000,         # Pa (2 bar)
    orifice_diameter=0.020   # 20mm orifice
)

K-Factor vs Flow Rate¶

# Using K-factor (pressure-dependent)
sprinkler = PropBuilder.sprinkler(
    id="K80",
    activation_temp=68,
    rti=50,
    k_factor=80,
    pressure=100000  # 1 bar → 80 L/min
)

# Using direct flow rate
sprinkler = PropBuilder.sprinkler(
    id="FIXED_FLOW",
    activation_temp=68,
    rti=50,
    flow_rate=60  # Always 60 L/min
)

Spray Patterns¶

Basic Spray¶

# Simple downward spray
spray = (
    SurfBuilder("SIMPLE_SPRAY")
    .as_sprinkler(
        part_id="WATER_DROP",
        mass_flux=0.015,
        median_diameter=0.001,
        velocity=5.0
    )
    .build()
)

Advanced Distribution¶

# Spray with droplet size distribution
spray = (
    SurfBuilder("DISTRIBUTED_SPRAY")
    .with_particle_generation("WATER_DROP", mass_flux=0.02, nppc=5)
    .with_droplet_distribution(
        median_diameter=0.0008,  # 0.8mm median
        gamma_d=2.4,             # Log-normal shape parameter
        spray_pattern="GAUSSIAN" # Gaussian or UNIFORM
    )
    .with_particle_velocity(6.0)  # Magnitude
    .build()
)

# Vector velocity (angled spray)
angled_spray = (
    SurfBuilder("ANGLED")
    .with_particle_generation("WATER_DROP", mass_flux=0.01)
    .with_particle_velocity((1.0, 0.0, -5.0))  # Angled downward
    .build()
)

Water Mist Systems¶

Smaller droplets, higher pressure:

# Fine water mist droplet
mist_drop = (
    PartBuilder("MIST_DROP")
    .as_water_droplet(diameter=0.00005)  # 50 microns
    .with_breakup(enabled=True)
    .build()
)

# Mist nozzle with high pressure
mist_nozzle = PropBuilder.nozzle(
    id="MIST_NOZZLE",
    k_factor=20,
    pressure=5000000,  # 50 bar
    orifice_diameter=0.0005
)

# Mist spray pattern
mist_spray = (
    SurfBuilder("MIST_SPRAY")
    .with_particle_generation("MIST_DROP", mass_flux=0.005, nppc=10)
    .with_droplet_distribution(
        median_diameter=0.00005,
        gamma_d=2.0,
        spray_pattern="GAUSSIAN"
    )
    .with_particle_velocity(20.0)  # High velocity
    .build()
)

Activation Control¶

Temperature-Based Activation¶

# Sprinkler activates at 68°C
device = (
    DevcBuilder("SPRINK1")
    .with_quantity("SPRINKLER_LINK_TEMPERATURE")
    .with_control(setpoint=68.0, trip_direction=1, latch=True)
    .at_point(Point3D.of(3.0, 2.0, 2.8))
    .with_prop("QR_SPRINKLER")
    .build()
)

Delayed Activation¶

# 2-second delay before activation
device = (
    DevcBuilder("SPRINK_DELAYED")
    .with_quantity("SPRINKLER_LINK_TEMPERATURE")
    .with_control(setpoint=68.0, trip_direction=1, latch=True, delay=2.0)
    .at_point(Point3D.of(3.0, 2.0, 2.8))
    .build()
)

Manual Control¶

# Activated by time
device = (
    DevcBuilder("TIMED_SPRAY")
    .with_quantity("TIME")
    .with_control(setpoint=10.0, trip_direction=1, latch=True)
    .build()
)

Nozzle Systems¶

For fixed spray systems without thermal activation:

# Define nozzle property
nozzle = PropBuilder.nozzle(
    id="SPRAY_NOZZLE",
    flow_rate=50,      # L/min
    pressure=300000,   # 3 bar
    orifice_diameter=0.01
)

# Nozzle surface (always on)
nozzle_surf = (
    SurfBuilder("NOZZLE_SPRAY")
    .with_particle_generation("WATER_DROP", mass_flux=0.01)
    .with_droplet_distribution(
        median_diameter=0.001,
        spray_pattern="UNIFORM"
    )
    .build()
)

Array of Sprinklers¶

# Create multiple sprinklers in a grid
sprinkler_locations = [
    (1.5, 1.5, 2.8),
    (1.5, 4.5, 2.8),
    (4.5, 1.5, 2.8),
    (4.5, 4.5, 2.8),
]

for i, (x, y, z) in enumerate(sprinkler_locations):
    device = (
        DevcBuilder(f"SPRINK_{i+1}")
        .with_quantity("SPRINKLER_LINK_TEMPERATURE")
        .with_control(setpoint=68.0, trip_direction=1, latch=True)
        .at_point(Point3D.of(x, y, z))
        .with_prop("QR_SPRINKLER")
        .build()
    )
    sim.add_device(device)

Suppression Effectiveness¶

Coverage Area¶

Typical sprinkler coverage: - Residential: 9-12 m² per sprinkler - Commercial (light hazard): 12-21 m² - Commercial (ordinary hazard): 9-12 m² - High-challenge: 6-9 m²

Design Density¶

Occupancy	Design Density	Flow Rate
Light Hazard	2.5 mm/min	30-50 L/min
Ordinary Hazard I	6 mm/min	60-80 L/min
Ordinary Hazard II	10 mm/min	80-100 L/min
Extra Hazard	12+ mm/min	100-200 L/min

Performance Tips¶

Computational Efficiency¶

# Start with coarse particles
water_coarse = (
    PartBuilder("WATER_COARSE")
    .as_water_droplet(diameter=0.002)  # Larger = fewer particles
    .build()
)

# Reduce particles per cell for testing
test_spray = (
    SurfBuilder("TEST_SPRAY")
    .with_particle_generation("WATER_COARSE", mass_flux=0.02, nppc=1)
    .build()
)

# Increase for production runs
production_spray = (
    SurfBuilder("PRODUCTION_SPRAY")
    .with_particle_generation("WATER_DROP", mass_flux=0.02, nppc=5)
    .build()
)

Sampling¶

For very large particle populations:

# Sample 1 in 10 particles
efficient_water = (
    PartBuilder("SAMPLED_WATER")
    .as_water_droplet(diameter=0.001)
    .with_sampling_factor(10)
    .build()
)

Validation¶

Always validate suppression systems against: - Required design density (mm/min) - Activation time expectations - Coverage area - Pressure requirements - Droplet size distribution

Common Issues¶

Sprinkler Not Activating¶

Check: 1. SPRINKLER_LINK_TEMPERATURE quantity is correct 2. Setpoint matches sprinkler activation temperature 3. trip_direction=1 (activate when exceeding setpoint) 4. Sufficient heat reaching sprinkler location

Insufficient Water¶

Increase: - mass_flux value - nppc (particles per cell) - Number of active sprinklers - Coverage area

Computational Cost¶

Reduce: - Particle diameter (fewer particles needed) - nppc value - Simulation duration - Use sampling_factor