PS-Seal (Tandem)

Composition and construction: how is the seal built?

Applications: where does the Tandem excel (and why)?

The PS-SEAL Tandem is mainly used in rotating equipment where reliability and service life outweigh the lowest initial cost. Think of pumps, mixers, agitators, stirrers, centrifuges, and process equipment in the chemical and petrochemical industries and in food & pharma. The tandem design is also interesting in applications with (medium) high pressure and under (extreme) vacuum, because two lips create extra sealing reserve and keep leakage better under control. The PTFE lip also offers a strong combination of low friction and wear resistance, which helps limit frictional losses and typically allows the seal to perform stably for longer than standard elastomer lip seals under comparable load. In practice, this can reduce maintenance and increase uptime, especially in processes where even a small leak already leads to quality or safety issues.

Material selection: what options are available and when do you choose what?

The PS-SEAL Tandem is configurable, and the selected PTFE compound largely determines how the seal behaves with respect to lubrication, chemistry, temperature, and wear. GYLON® Black (graphite-filled) is often the standard choice for general industrial applications with sufficient lubrication, because it offers a favorable friction balance and stable performance. For food & pharma, food-grade compounds such as GYLON® White or Blue are more commonly chosen, so you can meet FDA requirements and hygiene expectations. White is typically logical when you mainly want food compliance and chemical resistance, while Blue is often more interesting when you also want to accommodate (incidental) limited lubrication or better “dry-running” tolerance. For vacuum and (semi) dry gas services, or in cases of fluctuating lubrication, compounds explicitly developed for dry-running and pv loading (such as Econol-filled variants) are sometimes selected. In environments with abrasion or solid particles, wear-resistant compounds (such as MS or KF variants) can be a better match, but this usually also requires a critical look at shaft condition and surface finish, because abrasion affects the service life of any lip seal.

Material overview (guidelines)

Comparison: Tandem vs other PS-SEAL versions

Within the PS-SEAL family, the Tandem PS-SEAL is primarily intended as a step up in reliability and sealing reserve in one direction. The Standard PS-SEAL version has one lip and is often already a major upgrade compared to elastomer oil seals, but it lacks the additional barrier of a second lip. The PS-SEAL Dustlip version is mainly interesting when external contamination is your dominant issue, because the additional lip primarily acts as a shield. The PS-SEAL Reverse version is selected when the desired sealing direction or design goals better match a reversed lip orientation. The PS-SEAL Back-to-Back version has two lips in opposite directions and is therefore suitable when you want to seal on both sides or separate media. The Tandem PS-SEAL stands out because both lips are oriented toward the media, which builds extra security in that one sealing direction. In certain applications this can also be a practical alternative to more complex sealing concepts; depending on pressure, speed, and media, a PS-SEAL (Tandem) can sometimes replace a mechanical seal or reduce the need for one.

Choosing the right size and material (with standards and tolerances)

You select a PS-SEAL Tandem based on shaft diameter, housing bore, and width. In many cases the dimensions align with common oil seal sizes, but with tandem configurations the width or internal geometry can differ, so always check the product specification for the exact version. For stable sealing, fits and surface quality are essential. As a guideline, you can assume the housing bore is within a common H8 tolerance and the shaft within h11, with a good shaft finish on the sealing surface so the PTFE lips do not wear unnecessarily and are not damaged during installation. Avoid burrs, sharp edges, keyways without an installation sleeve, and spiral patterns from machining, because these can “promote” leakage or mechanically damage the lip. You then choose the material based on the media (chemistry and any food compliance), lubrication conditions, temperature, and the combination of pressure and circumferential speed. In terms of temperature resistance, depending on configuration, the PS-SEAL Tandem can generally perform from approximately -90 °C to +260 °C, which makes it suitable for both cold environments and high process temperatures.

In summary, Garlock PS-Seal Tandem is a reliable and versatile solution for shaft sealing in rotating applications. With its excellent resistance to high pressure, extreme vacuum, chemical aggression, and wide temperature range, this seal ensures dependable performance in demanding conditions. The utilization 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 Tandem for your shaft sealing needs.

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