Heinrichs Messtechnik GmbH
Page 110 of 122
OPERATING MANUAL TMU / UMC3
Density calibration
For continuous processes, where only small variations of temperature are experienced and where only liquid medias
of similar density are used, the user can perform a density calibration locally by at the place of installation.
Note:
Density measurement is not available for all sensor types.
Before proceeding with the density calibration described in this chapter ensure that,
your sensor is capable of density measurement.
Conditions
For a local density calibration the following conditions must be fulfilled:
The sensor must be suitable for a density measurement. Contact our service department to check the
suitability of your sensor for a density calibration. For all suitable sensors, the Heinrichs offers a 3-point
calibration with an accuracy of at least 5 g/l. Sensors, for which the manufacturer calibration is not available,
are not suitable for local single point calibrations.
For the local calibration the medium’s density must be known or be determined by a suitable procedure using
exactly the same process temperature present in the sensor during measurement.
The medium must be liquid. For gaseous media the density calibration is not suitable.
Procedure
The density calibration procedure is as follows:
The transmitter is powered up and the sensor is filled with the medium under operating conditions.
A waiting period of at least 15 minutes is to be given, to allow the sensor including its enclosure and flanges
can adopt the operating temperature.
After the input of the customer’s password select functional class DENSITY and “density calibration hot
medium” (See chapter 7.2.6.15, on page 79).
Independent of the type of liquid medium and its temperature the beginning of the calibration is confirmed
by selecting “yes”. Thereupon the transmitter captures the medium temperature and current resonant
frequency of the sensor.
Subsequently the function “measured values hot medium“ must be selected, the displayed measured values
of temperature and frequency are confirmed by pressing the Enter-key two times. In the next field the density
of the medium must be entered in unit of g/l or kg/m³. (See also chapter 7.2.6.16 on page 79).
Subsequently, the function “finish density calibration” is used to finish density calibration. (See also chapter
7.2.6.17 on page 79).
Finally the function “density measurement on/off” activates the density measurement. (See also chapter
7.2.6.1 on page 74).
Now the measured density and also volume flows can be indicated or assigned to one of the outputs e.g.
current output 2.
