Does your production facility have COPD?

COPD (Chronic Obstructive Pulmonary Disease) is a progressive disease in humans that makes it hard to breath. In general, the airways to the lungs become congested, restricting air exchange.

As I visit swine production facilities across the Midwest, I routinely see this same type of disease in production facilities. A very large number of production facilities (sow units, nurseries, wean-finish and grow-finish) have major restrictions somewhere in their ventilation system that results in higher electric expense, curtain hang up and doors slamming due to very high static pressures, curtains opening when it is colder outside than intended, etc.

While there can be a variety of causes for this facility ‘disease’, a major cause is incorrect attic inlets, usually at the soffit. If you can’t get air into an attic efficiently, how do you expect to draw it from the attic through ceiling inlets? Common causes of attic inlet restrictions include but are not limited to:
• Soffit sizing
• Installation of punched metal or house soffit materials
• Installation of insulation stops
• Soffits plugged with debris
• Ridge vents as the only attic inlet

This morning it was 46F in Mankato, MN. This means many facilities had their curtain sidewalls closed and were using the ceiling inlets for ventilation. As we enter the fall and winter seasons we will rely even more on this component of our ventilation system.

Before you become totally involved in the fall harvest, give your ventilation system a check-up to reduce the impact of COPD on your facility. Clean soffit screens, verify soffit opening dimensions (one square foot of attic inlet per 400 cfm of fan/ceiling inlet capacity) and clean/repair fan shutters.

If you are relying on ridge ventilators for attic (and ceiling) inlet capacity, every time the wind blows across the roof ridge-line you are restricting air because of the increase in uplift pressure due to the venturi effect of the wind at the ridge.

2 thoughts on “Does your production facility have COPD?

  1. I have seen the ridge vent over ride min ventilation on winding days when that is the only inlet to attic

  2. In the ventilation workshops we do in the upper midwest, Jay Harmon at Iowa State University has calculated that the uplift at a ridge with 10 mph wind is 0.05″ static pressure and it rises exponentially to 0.2″ at 20 mph. With this much uplift pressure it is easy to see why variable speed fans which have a terrible time dealing with high static pressures will fail to perform.

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