Process connection of DPT with diaphragm seal
To determine the liquid level in a tank, the differential pressure is assessed across a tank level. A diaphragm seal is used to directly measure the pressure across the level.
Due to a lower process attachment (25 mm or 50 mm) compared to the 75 mm diaphragm, flushing and draining links are suggested when flange reducer is needed.
If there is a danger of freezing liquid in the flange adapter / reducer room, or consideration should be given to an elevated viscosity heat tracing or heating circuit. The fluid boiling point should not be exceeded by heating medium (steam/oil).
Process temperature and ambient temperature should be considered to avoid the fluid boiling or affecting the measurement reaction time.
Based on the fluid characteristics, diaphragm material should be thoroughly chosen.
The internal quantity of the capillary fluid may influence the precision and response time of the measurement. Capillary with an internal diameter of 1 mm minimizes the impact of temperature variability but increases response time. Capillary with internal 2 mm diameter will decrease the response time but will more affected by the fluid dilatation.
Sealing fluids compatibility with line process liquids should be assessed to verify that it is appropriate and to discourage process stream contamination
In the presence of wax, slurries, clogs flushing rings should be considered. Flushing rings should be fitted with vent and drain facilities. Diaphragm seals should include isolation features to enable maintenance.