Techline CV Design Guide

FITTINGS:

When laying out Techline CV, you will need to use fittings. If you have chosen a GRID layout, you may need a transition fitting from the supply piping to the Techline CV. Further, you will use Techline CV fittings to connect the rows of Techline CV to the headers. If you are using a LITE layout, you will also use a transition fitting from the supply piping, as well as a fitting at the end or midpoint of the zone so that a flush point can be installed.

Netafim 17mm barbed insert fittings are designed to speed the installation as well as offer you a broad range of choices, (click here for fittings page).

The barbed end(s) of all Techline CV fittings is raised and sharp. This allows the fitting to be used with operating pressures up to 50-psi without clamps. If pressures are expected to exceed 50-psi, a clamp is recommended. Ensure that the clamp is secured over the raised barb.

Fittings are simply pressed into the tubing. No special tools are required. As with all polyethylene pipe, do not heat the tubing before inserting the fittings. It is not necessary and it can damage the pipe.

STAPLES:

Techline CV staples (TLS6) are used to hold dripperline in place. While most commonly used when Techline CV is laid on-surface or under a mulch cover, staples are also valuable when a layout is being assembled sub-grade before being covered with dirt.

Rule of Thumb: Use a minimum of one staple for every:
• 3 feet of dripperline in sand
• 4 feet of dripperline in loam
• 5 feet of dripperline in clay

Further, use 2 staples "x'ed" over each other with any change-of-direction fittings such as tees, elbows or crosses.

LINE FLUSHING VALVES:

Techline CV has a check valve in each dripper designed to hold back a 4 1/2 foot column of water (2-psi dripper closing pressure). Therefore, it may not be desirable to use an automatic Line Flushing Valve with Techline CV, since it could allow water to drain from the dripperline after zone shutdown.

• Line Flushing Valves are used to provide a cleansing action in dripperline each time the zone is turned on.

• When the zone is turned on, the flush valve begins dumping water into a sump located under it.

• The dumping of water (additional flow) allows the velocity of water inside the dripperline to increase momentarily helping to clean the inside walls of the tubing.

• This action moves sediments out of the zone and into the sump.

IF AN AUTOMATIC LINE FLUSHING VALVE IS DESIRED:

• It is because the desire to have a cleansing action outweighs the desire to hold the water inside the tubing when the zone is off.

• As such, place a Line Flushing Valve (one per each 15 GPM of zone flow) as far away from the source as possible. This will typically be somewhere along the exhaust header in a GRID layout and at the midpoint of the tubing in a LITE layout.

• When Center Feed layouts are used, install at least one Line Flushing Valve on each exhaust header.

• Line Flushing Valves should be buried in a valve box with a gravel sump adequate to drain approximately one gallon of water.

• See Air/Vacuum Relief Valves - click here

IF AN AUTOMATIC LINE FLUSHING VALVE IS NOT DESIRED:

• It is because holding the water in the Techline CV is desired and,

• Procedures have been established to manually flush the lines during the season.

• In this case, Techline Shut-Off Valves (TLSOV) or Figure 8 Line Ends (TLFIG8) should be located along the exhaust header, or at the midpoint of a LITE layout.

AIR/VACUUM RELIEF VALVES:

Because Techline CV is designed to keep water in the tubing, an A/VRV would only be used in conjunction with an automatic Line Flushing Valve as described in the previous section.

If you want to hold the water inside the dripperline after zone shutdown, (you are using a TLSOV or FIG8 in lieu of an automatic Line Flushing Valve) disregard this section.

An Air/Vacuum Relief Valve (A/ VRV) freely allows air into a zone after shutdown. It also ensures a vacuum doesn't draw debris into the dripperline. Further, they also provide a means of releasing air from the dripperline when the zone is turned on, thus eliminating air pockets and speeding up dripperline operation. (Because water stays in a Techline CV zone anytime the elevation across the zone is less than 4 1/2 feet, this is not an issue).

• On zones where an Air/Vacuum Relief Valve is desired, they are installed at the highest point(s) in the zone.

• To ensure that all of the rows of the dripperline can take advantage of the Air/ Vacuum Relief Valve, install it/them along a lateral that runs perpendicular to the dripperline laterals. This may be an exhaust header, or a special lateral connecting all the rows of dripperline, such as going over a berm.

In large scale irrigation systems where pumps and large diameter pipe are used, air that has been created must be expelled. As such, the use of Continuous Air Vents may be required on continuously and noncontinuously pressurized lines.