remove the vinyl cap and pour some water down the pipe, it will
drain out the hole and saturate the sensor area within several
minutes. A reading can then be taken to see if the sensor still
reads close to zero. Be aware that it takes some time for this water
to drain away; until then a representative sensor reading cannot
be obtained. Wait until the sensor and surrounding soil have come
back into equilibrium to take readings. It is best to check sensors
between seasons.
Cut pipes and vinyl caps can be ordered from IRROMETER
using the following part numbers:
PVC Cut Pipe — _____ inches.
(
*
specify length = sensor depth + above ground).
VTC — Vinyl Tubing Caps, come in bags of 100.
See Profile Probe Assembly
instructions on back.
*
WATERMARK ON PIPE ASSEMBLY INSTRUCTIONS
Optimizing Irrigation . . . Maximizing Conservation . . . Worldwide Since 1951
®
WATERMARK on Pipe Assembly
Instructions
WATERMARK Sensors can be easily mounted
individually or in multiples on PVC pipe to make a rigid
assembly for ease of insertion and removal. Follow the
recommended procedures below and on page two to
ensure a good assembly is created. Refer to the pictures.
1. Cut 1/2" class 315 PVC (thin wall SDR 13.5) (or 3/4"
CPVC, SDR 11) pipe to the desired length. Remember
that the pipe should be longer than the desired depth of
sensor placement to allow for some exposed pipe above
ground for easy access to connect the meter. Precut
pipes are available from IRROMETER.
2. Drill a small hole (1/8”), or saw a slot in the side of
the pipe near the bottom so that it will align with the slot in
the top portion of the sensor housing that gets inserted
inside the pipe. This allows for any water that gets trapped
in the pipe to drain away and provides a vent to allow the
sensor to exchange air with the soil. (Precut pipes from
IRROMETER come pre-drilled.)
3. Use solvent cement (PVC pipe glue) that is
approved for ABS to PVC transition connections and carry
the ASTM designation D3138, such as IPS Weld-On 793,
794 & 796 or Oatey 30900.
4. When cementing the sensor onto the pipe, be sure that
excess cement does not plug the vent hole nor puddle in the top
cavity of the sensor. When you insert the sensor into the pipe:
a.Align the vent slot in the top of the sensor with the hole or
slot in the pipe to create the vent/drain access.
b.Allow the assembly to dry upside down so that any excess
cement runs into the pipe.
5. Fold over any excess wire and insert it down into the pipe,
leaving a few inches protruding for access to connect the meter.
6. Bend the protruding wires down alongside the outside of the
pipe and slip a black vinyl cap over the top of the pipe to hold the
wires in place. The cap not only holds the wire in place, but keeps
water from entering the pipe and artificially influencing the sensor.
If the exposed wire becomes damaged, remove the cap and pull
out some additional wire, then make a new end connection
suitable for connecting the meter clips.
If the sensors are not removed seasonally, they can be
checked for accuracy while buried on pipe in this fashion. If you
