Purge Ventilation vs Continuous Ventilation - Doug Owens, New Fashion Pork, from the 2019 Iowa Pork Congress, January 23 - 24, 2019, Des Moines, IA, USA. More presentations at https://www.youtube.com/channel/UCEFNbfee_Rq3AfAFTRpuCrQ

1. Ventilation Panel Discussion
Doug Owens
Senior Service Manager
New Fashion Pork
January 24, 2019

2. Purge Ventilation vs
Continuous Ventilation

3. Purge Ventilation
• Purge ventilation is using a cycle time to run
fans and shut fans off to get the required cfm’s
in your barn
• Calculating run time for (2) 24 inch pit fans for
a double stocked nursery barn
2250 head X 13lbs = 29,250 lbs
29250 lbs x .12 cfm/lb = 3,510 cfm
3,510 cfm / 11,500 cfm = .305 x 100 = 30.5%
30.5% x 300 = 91.56 seconds
90 seconds on, 210 seconds off

4. Purge Ventilation
Advantages:
• You know the exact speed of your air every time the fan runs
• Possible LP savings?
• Fan always runs at 100%--don’t have to worry about burning fan
motors out from running fans too slow
• When running automatic inlets there is zero influence from a
pressurized attic

5. Purge Ventilation
Disadvantages:
• Fans can freeze up, seasonally
• You can manipulate this by adjusting your cycle times
• During the off cycle, there can be a back draft of air up into the
attic which can create moisture on your roof steel, causing it to
rust prematurely (if roof is not insulated)

6. Continuous Ventilation
• Continuous ventilation is allowing
your fans to run continuously, at a
set percentage.
• Calculating run time for (2) 24
inch pit fans for a double stocked
nursery barn
2250 head x 13 lbs = 29,250 lbs
29,250 lbs x .12 cfm = 3,510 cfm
3,510 cfm / 11,500 = .305 x
100% = 30.5%
• Can’t run fans at 30%--it will burn
the motor out
• Unplug one pit fan and run one pit
fan at 61%

7. Continuous Ventilation
GOD
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Advantages:
• No updraft into your attics
• Little easier to teach to new employees
• Not opening/closing automatic inlets as much, so little less wear
on that equipment

8. Continuous Ventilation
Disadvantages:
• Inlets are open 100% of the time, so if you run into a positive
pressure situation, you may over-ventilate your barn for a period
of time
• Have to remember to plug your 2nd pit fan in and also readjust
your minimum ventilation

9. New Fashion Pork:
What We Do:
• We run continuous ventilation through
out our system
• We do have one-off situations—
• Older traditional nurseries =
Purge Ventilation
• Half-stocked barn = more likely
to purge for the short term
• Random G/F sites that we’ve
struggled ventilate = modified
continuous ventilation run
one pit fan as continuous vent
and run your second stage fan
as purge

10. New Fashion Pork
Why:
• #1 reason we switched preserve our roof steel
• Easier to teach and explain to new employees
• There is no substitute for paying attention to what the
pigs are telling you:
• You may need to over- or under- ventilate barns on any given
day because of seasonal or even daily weather patterns

11. THANK YOU