Vaisala DPT146 Guide de l'utilisateur télécharger pdf (Page 57)

Chapter 6 _______________________________________________________________ Maintenance

VAISALA ________________________________________________________________________ 55

Calibration and Adjustment

DPT146 is fully calibrated as shipped from factory. The recommended

calibration interval is two years. If there is a reason to believe that the

device is not within the accuracy specifications, you can perform a field

check using the DM70 hand-held dewpoint meter, or an MI70 indicator

with another DPT146.

If the field check indicates that the DPT146 is not within its accuracy

specifications, contact a Vaisala Service Center or your local Vaisala

representative to have the DPT146 adjusted.

Field Check Using an MI70 Indicator

Vaisala recommends the following equipment for field checking:

- A fully charged MI70 indicator (the measurement display that is

included in the DM70 package)

- A calibrated reference probe that is suitable for the intended

measurement environment and dewpoint range. The DMP74B probe

is recommended for checking the dewpoint and temperature

measurement accuracy. For checking all parameters, you can use

another DPT146 transmitter as a reference.

- You also need a connection cable (Vaisala order code: 219980) to

connect the DPT146 to the MI70 indicator. If you have two DPT146

transmitters, you need two cables.

NOTE

In the procedure below, the readings of the transmitter and the reference

probe are checked simultaneously. You can also check the reference

probe and the DPT146 separately if they cannot be connected at the

same time.

Perform the check as follows:

1. Place the reference probe and the DPT146 in the reference

environment.

2. Connect the reference probe and the DPT146 to the MI70 indicator:

- Reference probe to Port I

- DPT146 to Port II

3. Turn on the MI70 indicator.

4. Check and adjust the environment settings if prompted. Refer to the

DM70 User’s Guide for the settings of the DMP74B probe.

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Vaisala DPT146 Guide de l'utilisateur Page 57