The existing air distribution setup in a PA Double.


Here is the new situation, as proposed by Gielen. Particularly notice the improvement due to less air blowing over the upper bed, and the importance of moving the walkways to the sides.


1.26 cfm/ft2. As a rule, at the pin heading stage you would work at about 40% of the fan RPM. However, at CJ they used a fan position of 80% during this stage, which instinctively seems too high for my liking. The outlet opening was too small, meaning the fan needed to run too fast in order to achieve the right level of fresh air. In addition, it appeared that with the fresh air inlet at a setting of 50%, just 26% of the fresh air actually reached the growing room. Blocking off a portion of the re-circulation air opening, and enlarging the outlets, would create a better ratio between fresh air and return air, meaning that the fan speed could be considerably lowered. In the existing situation at CJ, I measured a record-breaking overpressure of 174 Pa, much too high.” Gielen mentioned a handy tip to check if outside air is suitable to use. “If you hang an air sensor outside with a cotton wick in water, you can easily see if the outside air is suit- able to cool or dehumidify the room air. If the wet bulb outside indicates a lower temperature


10 MUSHROOM BUSINESS


than the dry bulb in the room, then outside air can be used. Is this not the case, the chilling unit will have to be activated to cool and dehumidify the air. This unit must have sufficient cooling capacity to effectively reduce the temperature and then heat the air and blow enough drier air into the room.” Gielen then went into more detail about air distribution in the famous ‘doubles’. He showed a film of himself experi- menting with a smoke machine to clearly illus- trate to the audience where the problems were. “The air flow speed is way too high, and more- over a large volume of this air is blown away to the rear of the room. Far too much air, some 70% of the total, is blown over the cropping surface on the upper bed. That can be changed. Airliners can be used to improve control of the air flow. Also it’s better to divide the air across the three air ducts at the fan side of the room, and not take it first to the opposite side of the room, as is happening at the moment. Air distribution over the beds can also be improved by altering the position of the holes or airliners and sending less air over the upper beds.” (see illustration with modifications). “Achieving a situation with better balanced air distribution and moisture control, calls for a few modifications in the PA doubles. These changes can be quite low-budget, but they will still result in clear improvements. Measures such as larger air outlet openings, partly blocking the recirculation air duct if fresh air is being used, adapting the air ducts, using a wet bulb sensor to check the outside air, removing the wooden walkways in the centre of the rooms if no picking is in progress and introducing water or steam at intervals to add more moisture to the air in winter will represent a huge step forwards, certainly in the quality of the mushroom crop.”


Pay attention, or 40 push ups! “Repeat after me!” was the battle cry barked by Major General Vinny Boles, a former senior American army officer, to the audience. His presentation was a cross between a hilarious drill exercise and a serious attempt to persuade the participants that they make mistakes in person- nel management techniques. “Human capital is one of a company’s most precious resources.” In his view, all those who are involved in the leadership of a company must first take a long, hard look at themselves before dealing with their workforce. After lunch, Brittany Stager spoke on using social media as a form of advertising. According to her, Facebook, LinkedIn and Twitter are excellent channels to put your product in the spotlights. By entering an online dialogue with consumers, and utilising plenty of links to your company’s website. “Word-of-mouth marketing works online too. The best endorsement is


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