Dynasonics TFXL User Manual

Intelligent Design Enables Conservation

Open ditch irrigation replaced by closed piped system with precise flow control

Gerald W. Knudsen, PE
General Manager, AgriTech Consulting
303-697-2123
[e-mail]

As we progress into the 21st century, water
promises to be one of our most precious resources.
Wise management and proper conservation of this re­source will become increasingly important, and inno­vative methods will have to be employed to save
water.

Automation coupled with intelligent design has
greatly increased manufacturing productivity world­wide while cutting waste and improving quality. A simi­lar approach was taken in a recent project
implemented by the Montezuma Valley Irrigation
Company (MVIC, www.mvic.us) in Cortez, Colo. in
the western United States.

The MVIC is a private non-profit company that
is owned by and provides irrigation water to 1,400
shareholders who are farming and ranching 37,500
acres in Southwestern Colorado. The MVIC water dis­tribution system provides water to the shareholders
from the Dolores River via two reservoirs, two main
canals and 17 distribution laterals. The canals and lat­erals cover a distance of 124 miles.

Figure 1: Open ditch irrigation canals were re­placed with a closed poly pipe water distribution
system. The piping system saves water by reduc­ing evaporation, cutting seepage and eliminating
end of channel water losses.

to also conserve one of the most precious resources
in the arid western U.S.

Our company worked with the MVIC on a study
to determine the best method to minimize water loss
in the May Lateral Canal. A decision was made to re­place five miles of open ditch irrigation canals with a
poly pipe water distribution system. Projected savings
were on the order of 1,000 acre-feet of water per year.

The MVIC recognized that an opportunity ex­isted to save substantial amounts of water by replac­ing the open ditch irrigation canals with a closed poly
pipe water distribution system (Figure 1). Towards that
end, they retained the services of our company,
AgriTech Consulting of Morrison, Colo.

Waste Not Want Not

As much as 60% of the water that enters an
open ditch irrigation canal is wasted via evaporation,
seepage and losses at the end of the canal. This
waste presented an opportunity for the MVIC to not
only save water and money for its shareholders, but

The pipe system has 45 branches off of the
main supply line. The main supply line High Density
Polyethylene (HDPE) pipe ranges from 12” to 36” in
diameter, and is pressurized from 30 to 50 psi as re­quired for shareholder sprinkler irrigation systems.
The turnout pipes that serve each shareholder are
also HDPE with a transition to polyvinyl chloride.
Turnout pipe diameters range from four to eight
inches.

Each branch turnout from the main header to a
farm is supplied with an ultrasonic flow meter and two
butterfly valves. The meter measures the amount of
water passing through the turnout. The first butterfly

Figure 2: The transit
time flow meters use
two transducers
mounted on the
outside of the pipe,
both of which
function as an
ultrasonic transmitter
and receiver.

valve is controlled by the MVIC and is used to set
flows according to the number of shares of water allo­cated to that particular shareholder. The second but­terfly valve can be used by an owner to shut off or
reduce water volume.

Each flow meter is either solar or battery pow­ered, providing substantial savings by eliminating
power wiring. This green feature not only saved on in­stallation, but will also provide ongoing savings in the
form of lower energy use. The key component of each
branch turnout is the flow meter, and the MVIC was
exacting in its requirements.

Reliable Flow Measurement

On older parts of the system, the MVIC is using
impeller flow meters that require annual maintenance
and are subject to plugging with sticks, moss and
other loose material in the irrigation water. To reduce
maintenance and eliminate plugging problems, a deci­sion was made to use a non-intrusive flow meter.

“After extensive review of many types of meters
from various manufacturers, a decision was made to
purchase ultrasonic flow meters from Dynasonics,”

says Jim Siscoe general manager of the MVIC.
Dynasonics is a division of Racine Federated
(www.racinefed.com), and a number of factors
entered into the decision to purchase their Model
TFXL meters.

The transit time flow meters use two transduc­ers mounted on the outside of the pipe, both of which
function as an ultrasonic transmitter and receiver (Fig­ure 2). The flow meters operate by alternately trans­mitting and receiving a frequency modulated burst of
sound energy between the two transducers.

These particular meters were found to have the
lowest installed cost, especially for larger pipe sizes.
Because one meter could be used for many pipe
sizes, design was simplified and the MVIC was able
to minimize stocking requirements.

Prior flow measurement was made via Parshall
Flumes or weir boxes with 5% to 20% accuracy, while
the new meters provide an accuracy of 1%. Relatively
high accuracy is important because tight control of
flow guarantees sufficient yet not excessive water de­livery to each shareholder.

Smaller turnouts aren’t solar powered or