Ventilation Systems for Swine Production - Purdue … · Ventilation Systems for Swine Production Jay Harmon ... The f\ൡn capacity for each room is designed for 60 cfm per pig conventional
36
Ventilation Systems for Swine Production Jay Harmon, Ph.D., P.E. Professor Agricultural & Biosystems Engineering
• Air temperature• Moisture level• Air temperature uniformity• Air speed across animals• Airborne dust and disease organism levels• Odor and gas concentrations• Combustion fumes from unvented heaters • Moisture condensation on surfaces
Presenter
Presentation Notes
Ventilation affects many aspects of the animal environment.
How Important is Ventilation? Actual Case in Hamilton County
• 30 % death loss– Cohorts at ½% death loss
• Complete new ventilation system– ½% death loss
• 200 pig nursery – losing 60 pigs/turn– Worth $35 each - $2100 loss each turn– Paid for in one turn
Negative-Pressure Ventilation Systems• Exhaust fans• Air inlets• Controls
• Total [HVAC] system– Heaters– Evaporative cooling
Vacuum or “negative pressure”
Presenter
Presentation Notes
Ventilation systems include three basic components, but may be much more complex.
Terminology
• cfm: Cubic feet of air exhausted per minute
• fpm: Air speed in feet per minute
• inches of water:Static pressure (difference between indoor
and outdoor air pressure)
Presenter
Presentation Notes
‘Airflow’ is a broad term that means different things to different people. The units used can really help define what is being measured and discussed.
Recommended Ventilation Rates (MWPS)
Sow & Litter 20 cfm/sow 500 cfm/sow
Nursery 12-30# 2 cfm/pig 25 cfm/pig
Nursery 30-75# 3 cfm/pig 35 cfm/pig
Finishing 75-150# 7 cfm/pig 75 cfm/pig
Finishing 150-250# 10 cfm/pig 120 cfm/pig
Gestating 12 cfm/sow 150 cfm/sow
Breeding 14 cfm/sow 300 cfm/sow
Minimum Hot weather
Presenter
Presentation Notes
Note the wide variation in rates for different types and sizes of pigs, as well as season. In many cases, the numbers listed are likely to increase as data shows that modern lines of hogs produce more body heat (natural consequence of more-productive, faster-gaining hogs… which is a different concept than hogs being more efficient users of feed). Note that ‘minimum’ rate is often used interchangeably for cold-weather rate. May want to note difference between ‘minimum ventilation rate’ and ‘minimum recommended rate’, especially as it applies to hot weather.
Example Design: 500 head nursery• Pigs enter at 12 lbs, exit at 60-70 lbs.• Minimum Ventilation
– 500 pigs x 2 cfm/pig = 1000 cfm• Maximum Ventilation
New section. Tab. Exhaust Fans Exhaust fans for a a tunnel ventilated 100’ wide double room wean to finish facility. The fan capacity for each room is designed for 60 cfm per pig conventional (pit fans and one end-wall fan) before it goes into tunnel ventilation.
Highlight desired static pressure range. Point out that fan speed may not change much with changes in static pressure, but airflow delivered and fan efficiency both fall off noticeably at higher static pressures. So… more resistance equals less airflow, greater cost to deliver each unit of airflow, and likely a hotter-running fan motor (shorter motor life expectancy).
Fan Types
Pit Fans
Wall Fan
Presenter
Presentation Notes
Point out how the fan is not restricted in these arrangements. Also, there’s little chance of manure – fan contact.
Example Fan Selection
CFM goal
Fan No.
Model CFM rating
Control Method
Total CFM
1000 to 1500
1 14” Acme 2030 VS 2030
4000 2 14” Acme 2030 VS or SS 4060
8000 3 20” Del Air 4210 SS 8270
17,500 4 36” Airstream 9900 SS 18,170
Fan Layout• 20 pens of 25 pigs• 8’ by 10’ pens
1
2
3
4
40’
44’
Raydot Center Air InletAir Inlets
Presenter
Presentation Notes
New section. Tab. Air Inlets Bi-flo counter weighted ceiling inlet.
Primary Roles of Air Inlets
• Distribute air throughout room as intended• Help maintain desired conditions in animal
zone [microclimate]
Presenter
Presentation Notes
Two slightly different, but equally essential functions.
Proper Air Distribution at Minimum Airflow Rate
End view of room
Presenter
Presentation Notes
Cold incoming air mixes with warm room air and slows down before reaching the pig space. What happens if the inlet opening is too large? …too small? Remember that the fan setting is usually controlled by something other than the inlet setting. This is a case (at the inlet) where air speed and airflow rate are inversely related. As the inlet is opened up, air speed decreases proportionately, while the flow rate through the opening probably increases somewhat.
Presenter
Presentation Notes
Inlets and exhaust fans work best as a system when the inlet air velocity and room static pressure are in the range shown.
Manometer (measures static pressure)
Presenter
Presentation Notes
This sort of tool is very important for managing a ventilation system. Unfortunately it is often absent, unused or not understood in actual livestock buildings.
Adjustable Opening
Presenter
Presentation Notes
Things to check for on inlets include: maximum open [throat] area, smooth regulation of opening, and ease of making adjustments.
Air Inlet Open on One Side
Presenter
Presentation Notes
The 4-way air inlets are closed on three sides and every other inlet pointing toward the outside wall is closed. The iso-wean pigs in this room were approximately 1 week old. With the low ventilation rates and small pigs, the producer wanted to direct airflow towards the outside wall and to make sure the open inlets would open. With this style of inlet and the placement, it is important to close off the opposing inlets going down the length of the room. If left open, the opposing air streams will cause a draft over the dividers in each pen.
Inlet Layout• Maximum 18,000 cfm• Need 15 inlets rated
at 1200 cfm each• Use 16
Attic Air Intake
• Port of entry for fresh air
• Must be effective opening
Presenter
Presentation Notes
Attic intake needs to be unrestrictive.
Attic Opening Needed
• Attic air intake (sq. ft.) = total hot- weather ventilation (cfm)/400 fpm
• Said another way…– Provide 1 square foot of opening for every
400 cfm of airflow• Example: Given 18,000 cfm
– 18,000 cfm/400 = 45 sq. ft. of opening
Presenter
Presentation Notes
We never want the building’s air intake to be more restrictive than the room inlets. That’s why we design for a slower air speed (400 fpm) and larger resulting open area. Note that the example uses same airflow rate as in previous scenario for inlets.
Unacceptable Air Intake
Presenter
Presentation Notes
Effective opening is only a fraction of the slotted vent area. Effective area is likely to be further reduced by debris collecting in slots.
Inlet Layout• 350 btu/hr-pig• ~175,000 btu/hr• Use 2 heaters
Controller
Set Point
Temperature
6
7
8
1 Variable-Speed & 3 Single-Speed Fans
Differential 2
Stage 2
3
Differential 3
Stage 3
4
Minimum
Airflow rate
Differential 4
Stage 4
5
Stage 1
Bandwidth 1
1
2
9
10
2 F 2 F 2 F 2 F
50%
?
Heater offset [1.5 oF] ensures heater is off when 1st stage fans are functioning
Tunnel Finishing
Tunnel – Pit Fans
Tunnel Endwall Curtain
Tunnel – 300 fpm “wind”
Inlet Openings
Ventilation Curtain
Curtain Controller
The Right System?
• Tunnel– Creates a “fake”
wind– More Fans– More Electrical
Usage– Cooling Potential– More Prescriptive
Management– Backup Needed
• Curtain Sided– Uses natural
weather patterns– Curtains vs Fans– More LP Usage?– Calm Days Difficult– Transition Difficult– Curtain Drops