Special Refining Company (SRC), located in Zaandam, the Netherlands, is an independent contract refiner dedicated to refining vegetable oils and fats for third-party customers as a service. To meet current and future challenges in food safety, SRC built a new refinery and upgraded their existing one to the latest technology. This gives their clients certainty in terms of yield, quality and food safety.
SRC has multiple storage tanks for a multitude of crude and refined edible oils. The tanks are closed, but non-pressurised designs, i.e. the edible oil products are stored at an atmospheric pressure. There was thus no need for differential pressure level measurement.
Initially, these narrow storage tanks had been equipped with a basic pressure transmitter for hydrostatic level measurement mounted at the bottom of the tank. However, the diaphragm material of the pressure transmitter was not up to the task as it tended to fail after a while due to the acids in the vegetable oil. Leakages had an impact on the measuring performance and caused a major deviation in tank level readings. SRC was therefore searching for a cost-effective, yet robust and reliable replacement.
The customer opted to replace the pre-mounted pressure transmitters with the OPTIBAR PM 3050. The KROHNE pressure transmitter is so compact as to allow a 1:1 exchange of the previous instrumentation without any additional pipe work. It combines excellent measuring performance with outstanding robustness.
The fully welded stainless steel (1.4404 / 316L) design makes the pressure transmitter very robust and resistant to the present process conditions. The stainless steel diaphragm of the device provides corrosion resistance to the fatty acids in the vegetable oils. The digital linearisation of the OPTIBAR PM 3050 enables a stable and accurate measurement signal. Due to its integrated temperature compensation, thermal effects on the sensor are eliminated.
The compact pressure transmitter was installed with a threaded connection. Front-flush installation was not necessary but could have also been provided together with a wide range of hygienic process connections if wished. The 2-wire device transmits its readings via the 4…20 mA output to the customer’s PLC for automated inventory monitoring.
Hydrostatic level measurement of edible oil with the OPTIBAR PM 3050
Storage tanks with KROHNE pressure transmitters
The KROHNE pressure transmitter turned out to be the ideal replacement for the previous instrumentation. Its compact design allowed for seamless integration into the existing infrastructure. There was no need for additional installation effort and long downtimes. SRC benefits from more reliable stock management. Faulty level measurements due to leakage are no longer an issue. Unlike the previously used pressure transmitters, the rugged, welded design of the OPTIBAR PM 3050 resists wear and leakage for long-term stable operation, so keeping maintenance costs low and plant uptime high.
KROHNE offers a wide range of pressure transmitters from a single source – from ultra-compact to process pressure and differential pressure transmitters. This involves the whole scope of supply from technical advice, product selection and sizing through engineering and manufacture to delivery, installation and after-sales service. A wide range of wetted materials is available for applications with different edible oil products, e.g. soy oil with a high concentration of salt where stainless steel diaphragms can no longer be used.