Vaisala PTB330 - Manual (Page 26)

USER'S GUIDE____________________________________________________________________
24 __________________________________________________________________ M210855EN-D
Pressure connections
The barometer is equipped with a barbed pressure fitting which is
ideal for 3-4mm internal diameter tubing. If you require some other
pressure fitting, you can replace the standard barbed fitting. The main
pressure connector in the barometer housing has a metric M5 internal
thread. It is, however, in practice possible to use pressure fittings with
a non-metric 10-32 external thread together with this main pressure
connector.
The barbed pressure fitting supplied with the barometer is not a static
pressure head and cannot be used in turbulent or high-speed wind
conditions. The barometric pressure measurement accuracy quoted for
the PTB330 series digital barometers does not include any wind or air
conditioning system induced measurement errors.
Protect the pressure fitting from the rain. If water gets into the
pressure connector it may cause errors in the pressure measurement.
The PTB330 barometers are designed to measure the pressure of
clean, non-condensing, non-conducting, and non-corrosive gases only.
If you use Static Pressure Head SPH10/20 with PTB330, make sure
the SPH10/20 tube is pointing downwards from PTB330. This way
the condensed water does not accumulate inside the tube and cause
measurement errors.