Friday, August 29, 2008

Valmont's Center Pivot Patent

Valley struggled throughout the 1950s and 60s to refine their product and develop a customer base. Valley built only seven center pivot systems in 1955. By 1960, production had still only reached 50 units a year. Then, by the end of the 1960s, the market took off – just as the original patent protecting Zybach's invention ran out. By 1972, there were 2,725 pivot systems in Nebraska alone. By 1980, there were 18,785. And by 2002, there were an estimated 258,000 center pivots installed around the world. Even before the patent rain out in 1969, other companies were bringing out their own systems and claiming that they weren't using ideas from Zybach and Valley. Valley disagreed. The company filed a number of patent infringement lawsuits. They won most of them and settled out of court on others.

For the irrigation industry, the 1970s were like the Internet "Dot Com Bubble" period of the 1990s – lots of new companies tried their luck and ended going out of business. All told, more than 80 individuals and companies tried to manufacture and sell center pivot systems through the boom years. For a time around 1973, sales were stimulated by the Soviet Union buying up huge quantities of American grain. But by 1980, the export market dried up, agricultural credit dried up, farmers were in danger of losing their farms and almost all of the center pivot companies went out of business.

Today only a handful of center pivot companies remain in the USA, and the four largest: Valmont, T-L Irrigation, Lindsay, and Reinke: all based in Nebraska.

Thursday, August 28, 2008

Sprinkler Systems Classification

Center-Pivot Sprinkler Systems are classified according to pressure or nozzle type. Although there is no definite boundary between high, medium and low pressures, it is commonly accepted to have the following classifications:
  • High-pressure systems have pressures of more than 50 PSI at the Pivot.
  • Medium-pressure systems have 35 to 50 PSI at the Pivot.
  • Low-pressure systems have less than 35 PSI at the Pivot. LEPA (Low-Energy Precision Application) and LDN (Low Drift Nozzle) can operate on pivot pressures of 15 to 25 PSI.
Nominal operating pressures at the sprinkler head or water-emitting devices are constant for a particular head.
  • Nominal pressures for LEPA devices are 6 to 10 PSI.
  • Spray nozzles, rotators and spinners are 10 to 25 PSI.
  • Small impact heads with modified nozzles are 20 to 45 PSI.
  • Small impact sprinklers with round nozzles are 30 to 60 PSI.
  • Large impact sprinklers are 45 to 80 psi. The range for large impact sprinklers depends on nozzle type and size.
Pressures needed at the Pivot depend on pressure losses in the lateral due to friction losses and elevation differences along the lateral.
Impact sprinklers usually operate at high to medium pressures, are installed on the lateral pipe, and irrigate over the crop. Spray and rotary nozzles operate at medium to low pressures, are installed on the lateral pipe or on drop tubes or pipes, and result in "down in the crop" irrigation. Irrigation down in the crop reduces evaporation and wind drift.
A user should select a sprinkler package with an application rate that matches the soil's intake rate, satisfies crop water requirements, and functions under local climatic conditions (wind).

Wednesday, August 27, 2008

Center pivot irrigation

Center-pivot Irrigation, is a method of crop irrigation in which equipment rotates around a pivot. A circular area centered on the pivot is irrigated, often creating a circular pattern in crops when viewed from above. The system is fed with water from the pivot point at the center of the circle.
Central pivot irrigation is a form of sprinkler irrigation consisting of several segments of pipe galvanized steel or aluminium, joined together and supported by trusses, mounted on wheeled towers with sprinklers positioned along its length. The inner sets of wheels are mounted at hubs between two segments and use angle sensors to detect when the bend at the joint exceeds a certain threshold, and thus, the wheels should be rotated to keep the segments aligned.
Centre pivots are typically less than 500m in length (circle radius) with the most common size being the standard 1/4 mile machine (400 m). Most center pivot systems now have drops hanging from a u-shaped pipe called a gooseneck attached at the top of the pipe with sprinkler heads that are positioned a few feet (at most) above the crop, thus limiting evaporative losses and wind drift. Drops can also be used with drag hoses or bubblers that deposit the water directly on the ground between crops. This type of system is known as Low Energy Precision Application. Crops may be planted in straight rows or are sometimes planted in circles to conform to the travel of the center pivot.
Most systems today are driven by an electric motor mounted at each tower. The equipment can also be configured to move in a straight line, where the water is pulled from a central ditch. In this scenario, the system is called a linear move irrigation system. Te
rrain needs to be reasonably flat, but one major advantage of centre pivots over alternative systems is the ability to function in undulating country.

Tuesday, August 26, 2008

Water conservation in Georgia

Water conservation hasn't always been a top priority for farmers in Georgia. That's because water has been plentiful. But fields have suffered several droughts in recent years. So many farmers have improved the efficiency of their irrigation systems by adding low-pressure nozzles that reduce evaporation loss, and they also have started to use soil moisture monitors that eliminate guesswork about when to water.
A few began using a new computerized system (center pivot irrigation systems) that allows them to spray water onto crops exactly where it's needed without wasting it in bogs or other unplanted areas. Farmers in southwest Georgia have conserved this way more than 10 billion gallons of water.
The farmers' irrigation systems (huge metallic structures that roll across fields spraying water), have been modified with electronic circuitry that makes it possible for farmers to program precisely where the water goes. Pivot Irrigation systems: lon
g, spindly, devices on wheels that "walk" slowly across fields spraying water were virtually unknown.

Monday, August 25, 2008

TRAXCO S.A. Center Pivot Components

We supply since 1991 original irrigation components and spare parts for all Irrigation Pivot brands to use in all types of irrigation systems. If your pivot irrigation equipment needs upgrading, we are the answer to repair, renovate or put your system back to work. We supply parts for every pivot system.
A Pivot irrigation System is a form of sprinkler irrigation consisting of several segments of pipe (usually galvanized steel or aluminum) joined together and supported mounted on wheeled towers with sprinklers positioned along its length. The system moves in a circular or linear pattern and is fed with water from the pivot point at the center of the arc.