Dripline, often referred to as Heavywall Dripline, is similar to drip tape. Dripline has emitters pre-installed at evenly spaced intervals and is a great solution for vineyards, row crops, and orchards. It is durable, resistant to clogging and delivers consistent volumes of water through pressure compensating emitters. Some models are available with an internal CNL to help prevent low head drainage. This allows the grower to make precise calculations without having to discard or rework them entirely due to head drainage.
The durability of Polyethylene irrigation tubing is well known, and dripline is no exception. It is constructed of the same material that “blank” poly tubing is constructed from and has a similar wall thickness at around 45 mil. Compare this to the 15 mil common to the thickest rolls of drip tape (25 mil from some manufacturers) and you can see why it is considered significantly more durable. This reduces the frequency of damage, and with normal use will help it endure for years. The infographic above illustrates the difference in wall thickness. 1 mil is equal to .001" so the infographic does not depict actual sizes, just the differences between them.
Heavywall dripline is also surprisingly resistant to freeze damage. When well drained, it is not uncommon for it to be left in the field over the course of winter. This reduces labor costs by a good margin given the time it can take to recoil and store at the end of every growing season.
Clog resistance is one of the most important features of any emission device to growers
and dripline is clog resistant enough that it can be used in subsurface applications. The pre-installed emitters in the pressure compensating dripline we carry each have their own individual inlet filter, one of the largest in the industry. The filter is engineered to trap debris that enters the line in its carefully designed grooves. These grooves not only trap debris, but their shape also creates turbulence. This turbulence dislodges debris and sends it down the line where it can subsequently be flushed.
While this does not completely negate clogs, it does reduce them significantly enough that the dripline can be confidently buried if necessary.
Dripline is notable for its consistent discharge across emitters. Apex PC Dripline from Irritec boasts a CV (coefficient of variation, essentially how much variation there is in the emitters’ discharge rates across the line) of less than 5%. The internal diaphragm also compensates for pressure spikes of up to 60 PSI for our PC Dripline and 50 PSI for our PC Dripline with CNL. This provides superior uniformity over elevation changes compared to non-pressure compensating driplines and drip tapes. The consistency allows the farmer to better plan nutrient delivery as well; the lower variation rates between emitters allows for a confidence not seen in less consistent delivery methods.
The CNL feature also contributes to consistent delivery. The CNL feature is an internal check valve that prevents low head drainage when the system is not in use. When low head drainage occurs, it has to be accounted for by the grower, a burden the check valve relieves. To a lesser degree, the internal diaphragm that allows the dripline to compensate for pressure spikes also helps prevent low head drainage unless the elevation drop is steep enough to overcome the minimum PSI needed for the emitters to drip. The non-CNL dripline requires 7 PSI to open its emitters. It would take about 16.17’ of elevation to generate 7 PSI. If there is elevation change equal or greater than that, the CNL feature would be needed to prevent low head drainage.
The heavywall dripline we carry is available in two diameters: .600” x .700” and .620” x .710”. These specifications are a common polyethylene tubing and heavywall dripline size. This makes a variety of compatible fittings readily available to accommodate almost any design or repair need. Perma-Loc Style Fittings, Barbed Insert Fittings and Compression Fittings are all compatible with dripline that shares these specifications. Note that compression fittings are compatible with specific outside diameter sizes and thus the blue insert is necessary for .710” dripline and the black insert is needed for .700” dripline. When using barbed insert fittings, it is recommended to use clamps to secure the tubing in place.
Though the heavywall dripline is incredibly durable and resistant to clogging, damage and clogs may occur at times. When they do, repairs can quickly be made using any one of the couplings; simply cut the damaged portion of dripline out and couple the remaining, undamaged lengths together. For temporary repairs, Polyethylene Tubing Repair Tape can be used.
Maximum run lengths are dependent on several variables: emitter spacing, emitter flow rate, inlet pressure, friction loss and elevation change. Each of these factors influence the maximum (and optimal) run lengths. There are other factors (tubing size and material, pressure loss from fittings) but the ones listed above are the primary influences.
The maximum run length of dripline is less than that of drip tape. This is largely due to the pressure compensating and check valve features since a minimum pressure is necessary to open the check valve. A minimum of 11 PSI at the end of the line is recommended to ensure the emitters can open and operate. The chart below shows the maximum run lengths for dripline with the common spacing options of 12”, 18” and 24”. The maximum run length chart assumes otherwise ideal conditions and it is recommended to keep the maximum runs shorter than what’s seen on the chart; this helps ensure success since conditions will not be ideal in the field.
The heavywall dripline we have available is commonly used for row crops, orchards, vineyards, locations with poor water conditions, sites with uneven topography, subsurface drip, and permanent irrigation systems
In addition to irrigating orchards in a straight row formation, heavywall dripline can also be formed into rings that go around the base of trees. This allows emitters to deliver water on each side of the tree, reaching the root zone on all sides.
Heavywall dripline suspended from a hook is the most common method of drip irrigation we see used in vineyards. Durable enough to handle exposure to the elements, coupled with the ability to provide precise nutrient delivery has made it the go to solution for vineyard irrigation. If a more economical solution is needed, simply forego the hooks and wire and lay the dripline on the surface of the soil.
Poor Water Conditions
As noted previously, the design of the emitter’s internal filtration allows for dripline to be used with water that is less than ideal. The turbulent flow path within dislodges debris that might otherwise clog an emitter. Clogged emitters is one of the most critical concerns growers face, and heavywall dripline is one of the solutions that resulted from these concerns. While proper primary filtration will always be needed, internal filtration at each emitter is another line of defense.
The pressure compensating feature helps ensure optimal distribution uniformity despite descending slopes and pressure spikes. Water pressure is increased by .433 PSI for every 1’ of elevation; in non-pressure compensating emitters this can cause water delivery to be significantly higher at low points in the system when the system is not operational. This makes for very sub-optimal distribution uniformity. At system shut-down, water will drain from the low points, further exacerbating the issue. The pressure compensation, and to an even greater degree the internal check valve, prevents water from draining out of the emitters after shutdown.
Drip irrigation is already regarded as efficient irrigation with minimal runoff and evaporation rates; this efficiency can be improved with subsurface irrigation and completely eliminate evaporation. Subsurface drip irrigation is the act of burying the dripline permanently below the tillage layer; studies suggest that subsurface drip could reduce water usage by as much as 50%.
There are some challenges inherent in subsurface drip, however. Visually inspecting for clogged emitters is significantly more difficult in a subsurface system, and labor costs and initial material costs are higher. If these challenges can be overcome, water use can go down and crop yields can go up.
Both types of dripline we carry can be used in subsurface applications due to the inlet filter at every emitter, however, we recommend using the Dripline with Anti-Siphon to help prevent debris from being siphoned back into the dripline through the emitter orifice. This will greatly reduce the risk of clogged emitters.
Permanent Irrigation Systems
Dripline’s ability to be used in a permanent irrigation system is somewhat related to subsurface irrigation (it’s more convenient to bury dripline in a permanent system), however dripline can be left above the surface in a permanent irrigation system as well. Aside from the general durability of polyethylene tubing, it is also very resistant to freeze damage. This allows it to be left above the surface in situations that other tubing or pipe would have to be recoiled or buried for frost protection. Polyethylene tubing gained in popularity in states with the coldest climates; its flexibility allows it to “bend but not break” and it’s not uncommon in even the coldest of states to see it remain above the surface.
The dripline still needs to be drained for the duration of the winter months, however. When water freezes it expands by approximately 11%; this expansion is a very powerful force that can break even the strongest and most flexible materials.
|.600" x .700" Pressure Compensating Dripline||.600" x .700" Pressure Compensating Dripline w/ CNL||Perma-Loc Fittings||Repair Tape|
|Barbed Insert Fittings||Clamps and Clamp Accessories||Support Hooks||Poly Tubing|
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