Evaporative cooling pad systems work in tandem with negative-pressure tunnel exhaust fans to protect commercial poultry flocks from fatal heat prostration during hot weather. As warm outside air is drawn through the water-wetted cellulose flute matrix, water evaporates and absorbs sensible heat, cooling the incoming air by 5 to 7°C.
However, improper pad area sizing, unlevel distribution headers, or poor water hygiene can cause severe mineral scaling, algae clogging, and uneven airflow. This guide covers the installation and maintenance requirements for evaporative cooling pads.
Sizing Cooling Pad Area and Face Velocity Standards
The most common engineering error is undersizing cooling pad area, which forces air through the pads too quickly, pulling water droplets into the poultry house and choking exhaust fan capacity.
Design Face Velocity: For standard 100 mm (4-inch) cellulose pads, design face velocity is 1.5 m/s. For heavy-duty 150 mm (6-inch) pads, design face velocity is 1.8 m/s.
Sizing Formula: Cooling Pad Area (m²) = Total Summer Exhaust Airflow (m³/h) ÷ [Face Velocity (m/s) × 3,600]. Static pressure resistance across clean, wet 150 mm pads should remain between 20 and 25 Pascals.
Water Distribution Piping and Sump Tank Installation
Uniform wetting without dry streaks is essential for maximum temperature drop:
Distribution Header: Mount the top PVC distribution pipe perfectly level using precision spirit levels. Uneven headers cause water to starve at one end and flood at the other.
Flow Rate & Sump Sizing: Deliver 6 to 8 liters of water per minute per linear meter of 150 mm pad. Size the water sump tank to hold 30 to 40 liters of water per square meter of installed pad area to accommodate pipe drainage when the pump stops.
Continuous Bleed-Off: As pure water evaporates, dissolved calcium and magnesium minerals remain behind. Install a continuous bleed-off valve discharging 5% to 10% of circulating water to prevent scaling and mineral crusting.
Algae Control, Cleaning, and Winter Shutdown
Daily Drying Cycle: Turn off the water circulating pump for 30 to 60 minutes in the late afternoon while keeping exhaust fans running. Completely drying the pads once every 24 hours dehydrates and kills green algae spores.
Chemical Cleaning: Never use concentrated chlorine bleach or harsh acid flushes on cellulose pads; chlorine dissolves the specialized resin binders that hold cellulose flutes together. Use approved non-oxidizing algicides or quaternary ammonium compounds.
Winter Decommissioning: Before freezing temperatures arrive, drain all water from sump tanks, pump lines, and distribution headers. Brush loose dust and dried algae from pad faces with a soft bristle brush, and install protective canvas covers over the exterior pad frames.
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