Wilo FK 17.1 - Page 184

en Maintenance and repair
184 WILO SE 2019-01
– With three sensors in series, the measured value range is from 60 to 300ohms.
– With four sensors in series, the measured value range is from 80 to 400ohms.
▪Pt100 sensor: Pt100 sensors have a resistance value of 100ohms at 0°C (32°F).
Between 0°C (32°F) and 100°C (212°F), the resistance increases by 0.385ohms per
1°C (1.8°F) increase.
At an ambient temperature of 20°C (68°F), the resistance is 107.7ohms.
9.6.5.3 Testing the resistor of the ex-
ternal electrode for sealing cham-
ber control
Measure the resistor of the electrode with an ohmmeter. The measured value must ap-
proach “infinity”. For values ≤30kOhm, if there is water in the oil – change the oil!
9.6.6 Note for the use of shut-off ball
cocks
If shut-off ball cocks are installed on the drain holes, observe the following points:
▪Remove the screw plug before opening the shut-off ball cock.
▪To drain the operating fluid, turn the lever to the direction of flow (parallel to the shut-
off ball cock).
▪To close the drain hole, turn the lever so it is at right angles to the direction of flow (to
the shut-off ball cock).
▪After closing the shut-off ball cock, screw in the screw plug again.
9.6.7 Oil change in the motor compart-
ment
WARNING
Operating fluid under high pressure!
A pressure of several bar can build up in the motor! This pressure escapes when the
screw plugs are opened. If screw plugs are opened without due caution, they can be
ejected at high speed! To avoid injuries, observe the following instructions:
• Adhere to the prescribed sequence of work steps.
• Unscrew the screw plugs slowly, but never unscrew them completely. As soon
as the pressure escapes (audible whistling or hissing of air), stop turning the
screw plug any further!
• When the pressure has completely dissipated, fully unscrew the screw plugs.
• Wear closed safety goggles.
WARNING
Scalding from hot operating fluids!
Hot operating fluids can also spray out when pressure is released. This can result in
scalding! To avoid injuries, the following instructions must be observed:
• Allow the motor to cool down to the ambient temperature before opening the
screw plugs.
• Wear closed safety goggles or face protection and gloves.