1. The document discusses power inlet management at weaning facilities to control humidity levels for newly weaned pigs. It focuses on using inlets to bring in cool, dense air and heat it to increase moisture carrying capacity before exhausting it outside. 2. It emphasizes measuring static pressure, air speed, and CFM at inlets to identify any unintended openings and ensure proper airflow. Inlets need to be adjusted to provide high-speed, uniform mixing of incoming air. 3. The document recommends maximizing inlet openings prior to moving side curtains to reduce temperature fluctuations and provide 45 CFM/head as industry standard. Installers need guidance to properly set inlet openings.

1. 1-22-20
Inlets: the good, the bad, the unintentional.

2. • Assumptions for this discussion
• Wean to finish facilities:
• Negative ventilation
• Curtain sided
• Soffit adequate effective opening (1 sq. ft/400 CFM)
• Pit fans clean with adequate opening. (1 sq. ft/400cfm)
• Weaned pigs average 24 days of age: 14-16 lbs
Power inlet management at weaning
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3. • What do we want to control?
§ Humidity, humidity, humidity
• How do we control it?
§ Bring cold relatively dense air into the pig air space.
§ Heat it to expand it and increase it’s moisture carrying capacity
• Latent heat of animals
• Lp
• Exhaust it to the outside
Power inlet management at weaning
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4. • At placement we want a small amount of air to come into the pigs space. This helps
us stabilize temperature.
§ But it must come in at a relatively high speed to mix and remove dead spots in
the air space. A uniform planned mixing of air
• We need control of our inlets.
§ Fans are just air pumps. Inlets control distribution
• Manual/weighted inlets
§ Freeze in position. Can be blown open by strong winds
Role of inlets
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5. What to measure?
• Manometers
• Measure static pressure of room
• Any unintended inlets?
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6. Measuring output • We measure airspeed at the inlet
• Calculate the CFM requirement
• Provide 1 square foot/800 CFM
through inlet openings
• Incoming air speed should be 800-
1000 ft/min.
• Adjust min fan speed to meet air
speed target
• Unintended openings and
poor pit fan efficiency are
the usual culprits
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7. Tool for measurement
• Inexpensive anemometer
§ $150.00
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8. • Prior to the move of side curtains or tunnel curtains we need maximum opening of
inlets.
• Industry now at 45 CFM/hd required prior to curtain moves
• Reduces YO-YO effect on room temps as a result of curtains opening too
soon.
• Many facilities not utilizing maximum opening available.
• Installers get little or no guidance on how to set inlet opening
Maximizing inlets
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9. Getting the max from your inlets
The opening of the inlet door should match the rough
opening in the ceiling to gain maximum air intake.
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10. Adjust winch stops to maximize opening
Adjust stops to match rough opening
2:1 for double back cable set-up
1:1 for non-double back
Reset controller min/max or travel time
Excessive opening causes excessive travel time and
movement
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