It was a serious tropical storm that hit the Culiacán region in Mexico at the end of August. With severe rain and wind the retractable greenhouse was attacked quite heavily – but it held up.
“The reinforced polyethylene roof coverings can’t blow off since they are suspended below stainless steel wires”, the team with Cravo explains – something they not only know from calculations but also from experience.
Survived 16 hurricanes
Cravo retractable greenhouses and cooling houses have proven their strength and durability over the years by having been hit by 16 hurricanes, cyclones or typhoons with winds up to 225 kph (140 mph) without the loss of any structure. “While some roofs have been damaged, not even one retractable roof covering has ever blown off in any of the storms.”
Hectares can be retracted in less than 6 minutes
“Growers have a choice to leave the roof closed during the storm to protect the crop or retract the structure and walls to protect the house in the event that the winds are forecast to exceed the design load of the structure,” explained Richard Vollebregt with Cravo. “One of the biggest benefits for those growers who live in areas prone to these storms is that they can retract hectares of roofs in less than 6 minutes allowing them to react only when the storm will hit their location.” This means that growers do not have to decide days ahead of a hurricane arrival whether to cut the poly off their roofs when a major storm is forecast.
If the winds are forecast to be greater than the design load, hectares of roof and walls can be automatically retracted in minutes to protect the structure and coverings. In the event of a power failure after the storm, the motors can be manually powered using an Allen key turned by hand or a drill that is powered by a battery or a generator.
Top photos: Cravo greenhouse two months after Hurricane Irma came through with gusts reaching 180 kph (110 mph).The roofs and walls were retracted before the hurricane. Conventional poly houses (lower two photos) were destroyed.
Source – https://www.freshplaza.com