Vaisala HMT310 - Manual (Page 29)

Chapter 3 ________________________________________________________________ Installation
VAISALA ________________________________________________________________________ 29
4. Mark both the fitting screw and the nut hex.
5. Tighten the nut a further 30° (1/12 turn) or if you have a torque
wrench tighten it with a torque of 80 ± 10 Nm (60 ± 7 ft-lbs).
0505-273
Figure 10 Marking the Nut
NOTE When re-tightening the nut after detachment the nut must be tightened
without increased effort.
6. Clean and grease the tightening cone of the fitting screw after every
tenth detachment. Change the sealing washer every time the fitting
screw is detached. Use high-vacuum grease (for example; Down
Corning, Europe) or a similar grease.
See also section Measuring at Overpressure, on page 21.
CAUTION In pressurized processes it is essential to tighten the supporting nuts and
screws very carefully to prevent loosening of the probe by the action of
pressure.
NOTE When HMT314 is installed in a process with pressure differing from
normal atmospheric pressure, enter the pressure value of the process (in
hPa or mbar) into the transmitter memory via the serial line (see Set
Ambient Pressure for Calculations on page 51).
HMT315 for High Temperatures
HMT315 is installed similarly than the HMT313 probe but without the
supporting bar. Refer to Appendix A on page 99 for more information on
the duct installation kit for HMT315.
To avoid incorrect humidity readings, the temperature differences
between inside and outside of the duct must not be remarkable.