PS-Seal (Back to Back)

Composition and construction

Applications and why this version is so well suited

Garlock positions the PS-SEAL as a solution for rotating applications where high circumferential speed, higher pressure, extreme temperatures, or a combination of aggressive and abrasive media present a challenge for conventional oil seals. In that context, the back-to-back version also fits: you choose this Non-Standard configuration when, within the same PS-SEAL technology, you deliberately need a different lip arrangement than the standard version. The datasheet also presents the PS-SEAL as an alternative to mechanical seals and braided packings in certain applications, precisely because the combination of PTFE-based lip materials and the PS-SEAL design can be a robust, maintenance-friendly solution in specific cases.

Materials: what options do you have and what are they good for?

Garlock directly links PS-SEAL performance to the selected lip material and mentions several GYLON® compounds that are also relevant for Non-Standard configurations (such as back-to-back). GYLON® Black is the standard material and is especially logical in lubricated applications due to its stable, low-friction behavior. For food, pharma, and beverage applications, Garlock mentions GYLON® White and GYLON® Blue with FDA and EN 1935 compliance; White is partly suitable for dry running, while Blue is recommended when dry running is important and you want extra flexibility and recovery. F-econol is also FDA/EN 1935 compliant and is interesting when, in addition to dry running, you also need suitability for vacuum. For abrasive duty, Garlock mentions MS (MoS₂) and KF (carbon fiber), with KF offering a good combination for partially abrasive media with good dry running properties. Garlock emphasizes that dry running makes the requirements for the counterface and shaft condition more critical, because tribology then becomes more decisive for service life and sealing performance.

Material Table

How to choose the right size and material (including standards and tolerances)

Size selection starts with shaft and bore dimensions, with the note that the PS-SEAL Back-to-Back falls under PS-SEAL Non-Standard. Garlock indicates that Non-Standard configurations are in principle available in the same sizes as PS-SEAL Standard, with the possibility to vary d1 and B slightly, and cites bore Ø H7 and shaft Ø h11 as the baseline fits. Material selection then follows from the medium, lubrication condition, temperature, and load: Garlock specifies −90 °C to +260 °C for the lip materials, noting that frictional heat can raise the seal temperature above the process temperature. For pressure, Non-Standard can, depending on the version, go up to 25 bar; at higher pressure Garlock recommends a p×v check and axial fixation. The counterface is also crucial: Garlock specifies Ra 0.1–0.4 μm, Rz 0.6–2.0 μm, and Rmax 4 μm and warns against helical/spiral marks due to the pumping effect and leakage risk. As a guideline, Garlock specifies a shaft hardness of 60 HRC, and for p×v > 20 bar·m/s a chromium oxide coating is recommended. Finally, with combinations of higher pressure and higher circumferential speed, the limits must always be verified, because that combination determines sealing durability.

Comparison with other Garlock® PS-SEAL versions

Within the Garlock® PS-SEAL family, the Back-to-Back is especially interesting when you deliberately need a Non-Standard lip configuration rather than the standard build-up. PS-SEAL Standard is the most straightforward choice for single-sided sealing and is often used as an upgrade from a conventional elastomer oil seal, but with the typical PTFE/GYLON benefits. The Reverse Lip PS-SEAL is a better fit when hygiene and cleanability are priorities and you want to limit dead spaces on the product side. Single Lip with Dust Lip PS-SEAL focuses on extra protection against external contamination, so dust or dirt puts less load on the working sealing point. You choose PS-SEAL Tandem when you want two sealing points in the same direction for extra security or service life, while Back-to-Back is more appropriate when, within the same PS-SEAL technology, you need a different sealing logic than standard or tandem.

In summary, Garlock PS-Seal Back to Back is a reliable and versatile sealing solution for rotating shafts. With its exceptional resistance to high pressure, extreme vacuum, chemical aggression, and wide temperature range, this seal ensures reliable performance in demanding applications. The use of Gylon as the sealing lip material further enhances the seal's capabilities, delivering effective sealing and increased uptime. Trust in Garlock's expertise and choose PS-Seal Back to Back for your shaft sealing needs.

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FAQ