Rain-gun Irrigation system can be designed with either Portable System where a portable lateral with rain-gun stand is progressively moved or a Fixed System where only a Raingun is required to be moved on underground outlets.
The installation cost for portable Rain-gun system is very low approximately Rs 2,500/- to Rs 3,500/- per acre, where required PVC underground mains & pump set is available at the farm.
PVC main pipeline is laid through the center of the farm with quick-fit riser -outlets (2 inch end plugged) spaced at every 30-40 meters or 120 feet approximately. These outlets get connected progressively to trolley wheel Stand (having RainGun mounted) through portable quick fit laterals of HDPE/Aluminum sprinkler pipes (2.5 to 3 inch diameter, 4 kg/cm2 Rating). HDPE pipe fittings like PCN, Portable Bend, End plugs etc are used to join the HDPE pipes to the outlet of main pipeline. HDPE pipes and fittings are readily available in the market.
After working at one position for around 2 to 2.5 hours (1.25 -1.5 acre-inch rain depending on the crop, season & soil) the Rain-gun is moved to the next position, such that the entire area is irrigated in a cycle of 1 to 1.5 week. The distance between two positions of laterals and two positions of RainGun is generally 120 ft for V-Skipper and 260 ft for V-Mariner.
Each skipper covers around half acre area in 2 to 3 hours of central positioning ( adjusting for overlapping requirement) having sprinkling radius of about 80 to 90 feet and thus with two Rain Guns you can cover around 1 to 1.5 acres irrigation in 2 to 3 hours as per the climate, crop requirement.
One RainGun suffices for 6 to 10 Acres area as per the pumping hours available. You can opt for two Rainguns working simultaneously to cover the area faster (if pumping hours is limited due to electric availability).
Generally a 20 Acres area requires about four Skipper Rain guns (Two working at a time with two standbys). For larger area Mariner Rain Guns can be used accordingly.
Only Rain-gun is required to be shifted progressively on these outlets, covering entire farm in short cycle.
PVC main and submarines pipeline are laid throughout the farm with 2 inch quick-fit riser outlets (End plugged) spaced at every 30 m to 40 m. These outlets get connected to Rain Guns (mounted on Tripod Stand) through fixed laterals of HDPE/Aluminum sprinkler pipes.
These Italian Rainguns are manufactured by world famous Sime of Italy, the pioneers in Raingun technology in the world and brought for Indian Farmers by VEDANT ENVIRO AGRO AND IRRIGATION (P) Ltd. since last more than 20 years.
It consists of a Raingun as per the model chosen + portable trolley stand on wheels + one connector to attach your HDPE sprinkler pipes to stand + One unique male-Female Quick-fit coupling set , so Raingun gets mounted or removed from the stand pipe like a bulb from its socket.
For portable set, the best choice would be HDPE, ‘Quick coupling sprinkler pipes of 4 Kg pressure rating , which being portable in use , can be assembled and dismantled easily and Raingun can be placed every half acre progressively using portable trolley stand with wheels for mounting Raingun on its supply pipe.
For larger area, Rain Gun can be positioned at say 120ft x120 ft in the field using underground PVC or HDPE pipelines of 75 to 100mm dia as main supply line with above spacing outlets, and connecting to it the 63mm or 75mm dia portable laterals of HDPE sprinkler pipes on both sides , having the Rain gun with trolley stand attached to its end. Rain gun unit gets moved such that it covers the entire area progressively.
Minimum requirement is 5 HP high head pumpset ( giving 30 to 35 meters head ) if water is very near to ground level. High head pumpset will have modified Pump impeller and have lower inlet / Delivery size e.g 2 x 2 or 2.5 × 2.
Pump H.P requirement can get increased to 7.5 HP or 10Hp depending on the depth of water in the well from ground level, the distance from well to the end of Farm area, and the Raingun model one wishes to use.
Instead of changing the existing low head pumpset in well , you can also add another 3 or 5 HP pumpset on ground level at the outlet pipeline of first Pump to use as Booster Pump.
It mainly depends on the effective root zone depth of the crops. Only upper 50% roots can suck and supply water to plants and any water going beyond this depth is not available to plants. Again the balance of Air and water in the soil is healthier for the plant . Thus on an average a Rain Gun model V-Skipper or Hidra can irrigate nearly 1/2 acre per position in about 1.5 to 2.5 pumping hours depending on the soil type, season and crop being irrigated. Using Flood irrigation, farmers nearly take much more time and water to irrigate as no control can be exercised.
All most all crops like Fodder, Groundnut, Maize, Vegetables like Onions, carrots, Cauliflower, cabbage etc, All types of Grains and, Pulses, Sugarcane, Plantation crops such as coffee, tea, cardamom, etc.,
Turbine Drive model are gear driven wherein its rotation speed is unaffected by changes in wind velocity and thus offering highest uniformity of Rain all over the area and hence are more costly. They are best under windy conditions at site, and preferred for high precision sprinkling.
Raingun is a large area covering Sprinkler generally replacing 8 to 15 sprinklers as per the model chosen and thus reducing labor requirement to great extent in shifting the sprinklers in the farm area. Raingun also gives choice to use as Auto Full or Part circle rotation with Droplet size management mechanism for optimum working under windy conditions.