Vaisala HMT310 - Manual (Page 61)

Chapter 5 __________________________________________________ Measuring at Overpressure
VAISALA _______________________________________________________________________ 61
CHAPTER 5
MEASURING AT OVERPRESSURE
This chapter contains important information concerning the use of
HMT310 in overpressure conditions.
HMT314 and HMT318 are designed for humidity measurement at
overpressure. The maximum measurement pressures depend on the probe
as follows:
- HMT314: 0 ... 100 bar (10 MPa), for pressurized rooms and processes,
probe is provided with a nut, fitting screw and sealing washer
- HMT318: 0 ... 40 bar (4 MPa), for pressurized pipelines, ball valve set
available
The actual pressure in the sampling cell needs to be set to the transmitter
by using the serial line command PRES (Set Ambient Pressure for
Calculations).
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.
Pressure Regulator Recommended
When sampling pressurized processes exceeding the maximum
measurement pressure of the probe, the pressure in the measurement
chamber must be regulated to acceptable level or below. It is
recommended to use a pressure regulator before the measurement
chamber to prevent significant pressure variations.