Tensiometer Test Pump Service Unit 1007
Service Units are designed to aid users in the placement and installation, interpretation of readings, and
maintenance of IRROMETER soil moisture indicators. Several helpful items are included in the kit. The primary
component of a Service Unit is a small hand vacuum pump. The pump is designed to seal on the reservoir portion
of the instrument body and is used to create a vacuum manually, evacuating any air contained in the
tensiometer. These instruments function with the greatest accuracy when all air has been removed. One Service
Unit will service multiple instruments. This is used to validate accuracy of the gauge on the IRROMETER being serviced.
Pump Features:
• Designed for outdoor field use
• Non-corrosive construction
• Easily serviceable
• Long lasting
OPERATING PRINCIPLE: The Service Units provide the
IRROMETER user with valuable tools to ensure their soil
moisture indicators function accurately and are easily
operated and maintained. The hand vacuum pump serves to
evacuate entrapped air from the IRROMETER body which
optimizes accuracy and response time. This is important for
initial installation and also for periodic maintenance
purposes, as air may be drawn into the instrument from the
soil under normal operating conditions. Viewing of the fluid
level in the instrument and refilling is made easier by using
the IRROMETER Fluid concentrate to color the fill water.
Included Chart Forms provide a convenient way to graph the
periodic IRROMETER readings for use when analyzing soil
moisture trends. The instruction booklet provides detailed
information on unpacking, preparing,
installing, servicing and storing
IRROMETERS as well as guidance
on instrument placement and data
interpretation.
MODEL “MLT” FILL & AIR REMOVAL INSTRUCTIONS — 1.
Remove cap, tip protector and plastic bag covering tip. 2. Place tip in
clean water and soak overnight – you do
NOT need to fill the instrument. Step 5
below will complete the filling process. 3.
Make IRROMETER field solution by
adding one drop of IRROMETER fluid to a
cup of clean water. 4. Fill syringe half full
with IRROMETER field solution. 5. To fill,
place syringe tip loosely in O-ring seal
(located in cap opening), depress syringe
plunger to squirt water into the body tube of
the MLT. Do not seat the syringe to the Oring in this step as it could force the gauge
needle against the stop. (RSU units do
NOT have a gauge needle). 6. To remove
air, place syringe tip in O-ring seal (located
in cap opening), press in firmly to make a seal. With instrument at 45
angle (gauge or RSU down or on the underside), PULL GENTLY on
syringe to create a partial vacuum on the gauge or RSU (on gauge
model, do NOT exceed full scale of gauge or 40 kPa/CB) and release
slowly. Pumping this way several times will get most of the air out of
the gauge or RSU. 7. Remove syringe by slowly twisting while pulling
out to avoid a rapid release of vacuum, fill instrument cap opening
with water. 8. Replace cap – tighten until gauge needle moves toward
De-airing in the Ground
De-airing Instrument
De-airing MLT
Filling MLT
4
stop. 9. Tip (body) of instrument can be removed by pulling out from the top housing. Be sure to
remove the cap before attempting to pull the tip (body) out to avoid damaging the gauge. Replacement
tips (bodies) are available.