The following attachments contain the Powerpoint Presentation and brochures provided by Netafim at a field-day organised by NCGA in February 2010, on "misting" as a method of controlling orchid shed temperatures during the summer months.
Netafim Powerpoint Presentation
Cooling for Greenhouses
Coolnet Brochure
Mist Guard Cooling Brochure
Multi-function Irrigation Controller
Coolnet pro superfine mister
Coolnet Pro superfine mister (2)
SpinNet Bridgeless Micro-sprinkler
SpinNet Bridgeless Mirco-sprinkler Shoulder Distributor
Pressure Compensated Drippers (for equal water application at all drippers)
The following link is to a glossary of terms compiled by Netafim relating to irrigation. It does not include terms relating to specific items of irrigation equipment.
http://www.netafim.com.au/glossary#e
Netafim is an Israeli based company that was established over 40 years ago and is the world’s largest micro-irrigation company. It has offices in over 110 countries and supplies a range of equipment to many horticultural and agricultural projects around the world. Their product range includes: drippers and driplines, micro-sprinklers, Arkal filtration systems, solenoid and control valves, water meters, air valves and a complete range of irrigation and climate control systems. Netafim prides itself in supplying a technically advanced product range with the on-going technical support from local representatives to ensure the growers achieve the maximum potential from their equipment. In New Zealand they have a warehouse facility in Auckland that supports over 70 Dealers nationally. Their customer base in NZ covers: grapes, apples, kiwifruit, avocado, citrus, intensive greenhouse, nurseries, wastewater and many others.
The following link contains some basic information on the physics behind cooling greenhouses with water vapour.
http://faculty.caes.uga.edu/pthomas/hort4050.web/hort4050/lectures/12/lec12.pdf
Notes on Misting:
In Northland (NZ) there is a trade-off between light and temperature levels in orchid houses during the summer months. Excessive shading can limit both plant growth and spike initiation/elongation while excessive heat causes plants to “shut-down” thereby reducing bulb and spike size. A number of options for achieving the optimum combination are available and include shed design, shading, ventilation, misting and roof watering. A number of growers have installed misting systems and this technology does, in some cases, offer a cost effective alternative to structural alterations (raising roofs and or increasing vent sizes). Misters have the advantage over conventional overhead sprinklers that, by generating small droplet sizes, heat can be extracted from the shed through vapourisation (water droplets being converted to water vapour by absorbing the latent heat of vapourisation and then being taken out of shed and replaced by “dry” air so that the process can be repeated). While it has been generally believed that the water from misting systems should not wet the plant material, research work and the experience of some growers indicates that this need not necessarily be a problem for cymbidiums (they are generally not in flower during the heat of the summer).
Misting systems require cleaner water and higher pressure systems than conventional in-pot and over-head watering systems. The Installation of a misting system may therefore require an up-grade of the basic water supply system in terms of increased availability, improved filtration and fittings that can cope with the increased water hammer arising from the repeated opening and closing of the misting solenoids.
Some growers have installed effective misting systems using mister/fans from Redpaths. Another grower has found that by using a combination of shade paint and misters he has managed to limited his maximum shed temperature to 35 degrees campared to 45 degrees when only venting was used.
