Installation

Transmitters in cell design are installed between the connecting flange of the measuring point and a blank flange. Transmitters in flange design are installed directly to the connecting flange of the measuring point. The respective pressure level of the blank flange or of the flange remote seal must be taken into consideration.

The pressure transmitter should be installed below the connecting flange; pressure transmitters for differential pressure should be installed below the bottom connecting flange. This arrangement must be selected in the negative pressure range.

For measurements in the overpressure range, the transmitter can also be installed above the connecting flange.

For a good transmission characteristic, the capillaries between remote seal and pressure transmitter should be kept as short as possible.

Shifting the measuring range

If the two connecting flanges are installed at different heights for measurements with two remote seals, an additional differential pressure is generated due to the oil filling of the remote seal capillaries. This additional pressure causes a shift of the measuring range that has to be taken into consideration when setting the pressure transmitter.

A shift of the measuring range will also occur when you combine a remote seal with a pressure transmitter and when the remote seal is not installed at the height of the pressure transmitter.

Pressure transmitter output

When level, interface or density increase in closed containers, the differential pressure and therefore the output signal of the pressure transmitter increases as well.

For a reverse relationship between differential pressure and output signal, the start of scale and end of scale must be reversed with SITRANS P.

For open containers, an increasing pressure is usually assigned to an increase in level, interface or density.

Effect of ambient temperature

Try to avoid temperature differences between the individual capillaries and the individual remote seals.

Temperature fluctuations in the area of the measuring unit cause a change in the volume of the fill fluid and therefore measuring errors.

Notes

• For interface measurements, the interface must be located between the two nozzles. In addition, the fill level of the container must always be above the top nozzle.
• A constant level of the process medium is required for density measurement. The level should be above the top nozzle.

Possible combinations of pressure transmitters and remote seals