Test PB Collection: FTE

Filter station with both sand media filters and screen filters Photo: L. Schwankl.Filters are most frequently located at the head of the microirrigation system, but they may also be located in the field (secondary filters, often screen filters).

Flushing of drip tape lateral ends Photo: L SchwanklA 200-mesh filter will not remove particles of fine sand, silt, and clay or fine particles of algae. They will pass through the filter and be deposited in the drip lines.

Pre-set pressure-regulating valve at the head of a drip tape lateral line. Photo: L. Schwankl.Pressure-regulating valves are used in a microirrigation system to maintain a desired, constant pressure downstream of the regulating valve even if the pressure upstream of the valve fluctuates.

Liquid-filled pressure gauge. Photo: L. Schwankl.Due to the elements, pressure gauges installed in a microirrigation system do go bad.

The display of a propeller meter registers both gallons per minute and total gallons. Photo: L. Schwankl.Flow meters serve the dual purpose of providing water application information for irrigation scheduling purposes and monitoring for clogging (for more information, click here).

Here is an example of how to determine the average discharge rate for emitters in a drip irrigation system. Drip emitters were sampled in a vineyard system designed with two 0.5 gph drip emitters per vine and the vines planted on a 7 foot x 11 foot spacing.

Microsprinkler use in a young almond orchard. Photo: L. Schwankl.Microsprinklers were sampled in an almond orchard designed with a single microsprinkler per tree and with the trees planted on a 16 ft x 22 ft spacing.

The utility of the pressure measurement information you can gather from a SDI system is limited due to there being so few locations at which you can take measurements. If you only gather measurements at the head end or tail end of the tape lateral lines, these pressure readings should be consistent.

Drip tape used to irrigate spinach. Photo: D PorterSubsurface drip irrigation (SDI) systems can use either drip tape products or drip tubing systems with either in-line or built-in emitters. The "hard" drip tubing systems use the same type of drip tubing as used in surface drip systems.

Subsurface drip irrigation (SDI) drip tubing microirrigation systems are most commonly used for tree and vine (permanent) crops. These systems come in a variety of designs so it is difficult to provide evaluation guidance that applies to all installations.