Safe to run dry, lip seals have proven themselves for fruit juice concentrate

Jung Process Systems has comprehensive experience in pump design and selecting the correct seal from their numerous successful installations in the fruit juice industry. Particular requirements for the sealing technology are created when pumping viscous, sugary content, fruit juice concentrate. Which such applications, Jung can equip the HYGHSPIN steel screw spindle pumps with special lip seals as the shaft seal. The lip seals can run dry, also without a separate flushing system. In addition, collision damage can be avoided from bonded sealing surfaces. By eliminating the potential vulnerabilities in the sealing system, the pump availability is considerably increased; acquisition, maintenance and spare parts costs are significantly reduced.

Especially for fruit juice concentrates with high sugar content, single-acting standard mechanical seals cannot be considered. When the pump is stopped, the sliding surfaces can easily stick together and then break during a restarting process. Single-acting mechanical seals with reduced sealing surfaces can provide effective protection, but are however not safe to run dry. Consequently flushed double-acting mechanical seals have established themselves in order to prevent destruction of the sliding surfaces due to insufficient lubrication and overheating. Therefore the danger of unintentional seal failure is indeed banned but it is still not really a cost-based attractive solution for a run-dry safe shaft seal. An external purge system is required. In addition, difficulties arise when fruit juice concentrates are conveyed in a frozen state. At temperatures below 0 °C, water for flushing the seals is not an option due to icing. The utilisation of a circulation system in connection with alternative flushing media is then necessary, such as thin liquid food oils. This then causes investment and maintenance costs. A circulation system requires continuous control as undesirable germs can begin to concentrate. If a flushing medium on the basis of alcohol is utilised to reduce the freezing temperature, then it must be noted that the flushing medium will be lost due to the evaporation of the alcohol and must be replenished regularly.

Lip seals are run-dry safe

To eliminate this vulnerability in the sealing system, Jung Process Systems has equipped the HYGSHSPIN steel screw spindle pumps for fruit juice concentrate with lip seals. The sealing of the pump shaft implementation is executed by means of a self-lubricating PTFE lip seal. An external purge system is not required, so that the lip seals are particularly advantageous for mobile pumping systems.

The ready to install seal system is simply designed and constructed, easy to clean and cost effective compared to single and double mechanical seals. Only the sealing lips must be replaced in cases of wear. The feedback from customers has been very positive, the service life of the seals is excellent.

Jung Process Systems at Brau Beviale in Nürnberg, Germany from 10th-12th November 2015:

Hall 6, Stand 406