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In tunnel-ventilated poultry houses, evaporative cooling pad performance directly impacts bird welfare and productivity during summer. Two critical factors determine system effectiveness: proper pad sizing and water quality management.

Pad Sizing Principles

Pad area should be determined by total tunnel fan capacity, not house dimensions. Industry standard recommends one square foot of six-inch pad for every 350 cfm of fan capacity, equating to a design velocity of 350 ft/min through the pads. Insufficient pad area increases static pressure, reduces airspeed, and diminishes bird cooling. A 25% reduction in pad area can decrease airflow by 10% or more and reduce wind chill effect by 3°F or more. When sizing for high-speed houses (600–800 ft/min air velocity), pad area should be calculated based on total fan capacity at design static pressure of 0.15–0.20 inches.

Water Quality as a Performance Factor

Water quality is equally critical. Evaporative pads require pH between 6 and 8 for optimal performance. As water evaporates, minerals concentrate, forming scale that reduces cooling efficiency. Research shows mineral scale formation can reach 168 grams per 1,000 liters of water consumed. Heavily scaled pads can accumulate over one kilogram of mineral deposits, significantly restricting airflow and reducing evaporative efficiency.

Continuous bleed-off is essential—recommended rate is 1 gallon per hour per linear foot of pad length. Systems should maintain sump pH between 7 and 9 and hardness below 110 ppm. Regular flushing (weekly recommended) prevents scale buildup and preserves pad life.

Synergistic Benefits

Properly sized pads combined with proactive water management deliver measurable returns: cooling efficiencies of 70–80%, incoming air temperature reductions of 5–15°F, reduced bird mortality, and improved feed conversion. The synergy between adequate pad area and clean water circulation ensures consistent cooling performance throughout the hottest periods, protecting flock health and farm profitability.

Need help optimizing your cooling system? Contact us for a customized pad sizing and water management assessment.