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Airbag Ventilation

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John Gadd

Function: Blog: Pig Management
John Gadd, after training in Scotland 50 years ago, worked as stockman on several pig farms and managed several more before joining a large agricultural chemists as pig product manager. He was then technical director of a pig feed concentrate firm and also helped run their pig farm, then the largest in Britain.

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The hot weather is now upon us in the Northern hemisphere. Travelling the world, it surprises me that more producers aren`t using Airbag Ventilation, this valuable ventilation system either as a back-up method to alleviate hot weather stress, or as a full-time device to get over the common problem of over closed-up nurseries (to retain heat) when an icy wind streams around the building in the depths of winter.

The hot weather is now upon us in the Northern hemisphere. Travelling the world, it surprises me that more producers aren`t using Airbag Ventilation, this valuable ventilation system either as a back-up method to alleviate hot weather stress, or as a full-time device to get over the common problem of over closed-up nurseries (to retain heat) when an icy wind streams around the building in the depths of winter.
Why is it so useful?
  1. It is simple to install.
  2. Air can be placed exactly where it is wanted.
  3. The farmer can make 80% of the gear himself, given simple instructions.
  4. Thus it is cheap.
  5. Maintenance is easy and accessible.
  6. The fan(s) runs at a high speed thus overriding outside wind pressure, so the system is windproof.
  7. The fan is linked to a temperature sensor(s) in the normal way.
  8. On a permanent installation the system can be designed on a recirculation basis so that in cold weather heat is conserved with a minimal but adequate supply of cold air introduced from the outside.
  9. In very hot and still conditions the air can be directed directly on to the pigs, thus delaying the introduction of evaporative water cooling. This saves water - expensive to remove as slurry.
What does it consist of?

An ordinary, and cheap propeller fan/fans are situated at the top of a gable end. This leads into a simple air-straightener cylinder inside the building (which can be home-welded). This is needed to remove the twisting of the airbag tube due to the torque from the fan. A tapering tube made from heavy duty (500 gauge) polythene is clamped to the cylinder with a loosening nut to rotate the tube so as to allow the air to be directed where it will do the most good in hot weather or cause least discomfort in cold conditions. The tube runs the length of the piggery. In wide-span buildings more than one airbag is used from their own fan. Tapering the tube ensures the same exit air pressure is obtained both close and far distant from the fan. Given the correct design pattern the producer can easily make the tube/airbag himself - further cost savings. D-shaped holes (called `sipes`) are cut at prescribed intervals down the tube - this ensures even and correct air projection and volume.
Obviously from the above description some design specifications are needed. These I will provide in my next blog.
This system deserves far better recognition than it seems to be getting. I hope I can encourage you to try one and see.

by John Gadd

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5 comments

  • # 1

    Jan Veltkamp

    Don't use this bag system. It is difficult if not impossible to clean. It creates condensation and thus dripping on pigs and floor. The tube is not very durable. last but not least the ventilation doesn't work in practically as is expected when seen at first. I took it out, replaced it with air channel underneath the (slatted) walkway and instantly all my mycoplasma problems are gone. I don't even vaccinate anymore. Conclusion. The tube system looks interesting at first sight, is easy to install, is cheap but doesn't do what is expected.
  • # 2

    Mari van Genugten

    I donn't understand your system. Please make some drawings. what is the installed ventilationcapacity pro animal ? As I understand t well, it's a overpressure system.

  • # 3

    Irma

    Sir,
    It would be best if we can see some pictures
  • # 4

    Vladimir (UKRAINE)

    Very effective system
    We use this system more than 3 year.
    I can send some pictures.
    Condensat: installing above slatted walkway. Impossibility of cleaning - 1 tube 30meters from polyethilene 100 mkm cost approx. 3-5Euro. We replace it every 6 monthes. One remark - we use it mostly
    on winter - very good distribution of small air stream in stable.




  • # 5

    John Gadd

    Replies to comments:
    Yes, it is a pressurised system.

    * Ventilation capacity? Specifications follow in my next blog, as promised.

    * Drawings also follow next blog.

    * Condensation? Our reader is almost certainly introducing too much icy cold air in a straight-through system. The simple straight-through system works fine in temperate to hot conditions. In winter or distintcly cold conditions, add-in the hybrid recirculation idea - or choose a more conventional system.

    * Dust? A recirculation system of course recirculates the dust with the air. This is minimised with two generous (1m square) gauze/ fine cloth filters backed by chicken wire on a light wooden batten frame. These are fixed just outside the recirculation flap/shutters.These filters can be taken down, if fixed wirth butterfly nuts, once a week and vaccuumed, a five minute job. If you need to do this more than once a week , then look to reducing your dust levels. The filters themselves alleviate a dusty atmosphere anyway. They increase the powerload requirement of course, but this is less costly than dust - the `hidden` respiratory aggravating factor.

    * Durability? This reader is probably using too thin polypropylene - 500 guage is minimal. Or the trunk is not supported properly using a tailored `web` fixed to light wooden battens down the narrowing length of the trunking so as to even out the abrasive pressure on the supports. Or there are insufficient support fixings - a common failing. One per metre is advisable as the trunking `shivers` a lot. Strengthen the suspension points with Duck Tape.

    Like all innovations there is a lot of knowhow involved. Good ideas usually aren`t born in a day but are the result of a lot of people`s experience over time.

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