DOUBLE-ACTING SEAL FOR PHARMACEUTICAL APPLICATION
Pharmaceutical industry seals used in aseptic machines must keep the “dirty” substances tied to the internal part of the machinery in an isolated area and, at the same time, keep dust and cleaning sanitizers out of “mechanical” part of the machine. Materials, also those which are not in contact with drugs, must be certified according to food regulations and, if it is possible, also according to the USP Class VI regulation, that is mandatory for drugs contact.
An important producer for pharma machines had noticed sealing and wear problems during the roto-translating movement on the actuator cylinders in an aseptic environment and asked us to identify a solution that could have reduced wear without changing the machine performances and configuration of the machine.
Our technical department studied the application and the parameters involved such as low pressures, aseptic environment and strict material certifications requirements.
After evaluating both the applications and operating conditions, our technicians proposed the use of an innovative profile resulting from experience on food machinery with double-acting seals and scrapers, and the profiles used in case of aggressive sanitizing processes, which are typical of the pharmaceutical industry.
In particular, the solution has a pneumatic gasket shape inside the cylinder. Its energization it’s realized by a stainless steel spring, in which a sharp-edged scraping lip has been integrated towards the outside, with radius connection with the closing flange. In this way, cleaning is easier and the accumulation of contaminants from the outside is avoided.
The seal was realized in SINTEK PK20, a PTFE compound material filled with super polymers. It complies with all application needs such as FDA, EC 1935/2004, USP Class VI and GB certifications. The solution solves also the customer’s need of ease in the washing, in particular in the lips zone.
The customer, who had already used virgin PTFE in other applications, had asked us to develop the solution with a similar, but more resistant to wear, material. Therefore SINTEK PK20 was evaluated with great interest as it is just slightly affected by wear and without flaking of the material. The wear tests carried out in our test room on this profile simulating the operational conditions made it possible to promptly evaluate customer’s need. The wiper lip did not deform plastically and, while not energized, it met the customer’s requirements.
The SINTEK PK20 seal has solved all the application problem, and also drastically reduced the friction and decreasing energy consumption in the machinery.
“I made several torque absorption measurements and the ATP seal led us to a drastic reduction in friction and the torque required for rotation. Furthermore, after over 100,000 cycles, the low pressure seal was still guaranteed and also the wear of the material was really limited”