FLOWSERVE

FLOWSERVE seal type designations refer to standardized dimensional and design families. For example, Type 21 is a general-purpose single-spring seal with a carbon rotating face and a stationary seat, commonly used in water and light chemical services. Type 68 is a heavy-duty single-spring seal designed for higher pressures and temperatures, often specified for hydrocarbon or diesel applications. Type 51 and Type 52 are narrow cross-section seals for compact pump stuffing boxes. Type 16 is a unitized rotary seal that simplifies installation. Each type has defined shaft diameter ranges, working lengths, and spring-load characteristics. Always confirm the type designation against your pump's seal cavity dimensions.

Selection requires three key parameters: shaft diameter (measured at the seal location), working length (the distance from the seal face to the gland face when installed), and the fluid being sealed. The FLOWSERVE part number encodes these—for example, MPN 21-100-10 indicates Type 21, 1.000 in shaft diameter, and a specific working length. Also verify the elastomer material: Buna-N (Nitrile) is suitable for petroleum oils and water up to 100°C, while Viton (FKM) handles higher temperatures and aggressive chemicals. Stainless steel springs (18-8 or 316) resist corrosion. Cross-reference your existing seal's MPN or dimensions with the catalog to ensure fit.

FLOWSERVE seals are designed to meet industry-standard dimensions for common pump seal cavities, but they are not direct drop-in replacements for all brands. Many FLOWSERVE Type 21 and Type 68 seals have dimensional equivalents in other manufacturers' lines (e.g., John Crane, EagleBurgmann), but spring force, face materials, and elastomer compatibility may differ. Always compare shaft diameter, working length, and gland bolt pattern. 3G Electric provides MPNs for each SKU to facilitate cross-referencing. For critical applications, consult the pump manufacturer's seal specification or a FLOWSERVE application engineer.

The FLOWSERVE seals available through 3G Electric typically feature a carbon rotating face (ring material), a stationary seat (often ceramic or tungsten carbide, though not specified in the catalog), and springs made from 18-8 stainless steel or 316 stainless steel. Gasket (elastomer) materials include Buna-N (Nitrile) and Viton (FKM). For example, SKU 793KC0 uses a Buna gasket and 18-8 spring, while SKU 793K82 uses Viton. The seal type designation (e.g., 21, 68) determines the face and seat materials. Always verify compatibility with your process fluid temperature and chemical composition.

Yes, FLOWSERVE Type 21 seals are available for cooking oil applications, as indicated by SKU 5NC14 (MPN 21-137-04), which is specified for cooking oil. However, FLOWSERVE does not universally certify all seals as food-grade. The elastomer and face materials must be compatible with food-contact regulations (e.g., FDA 21 CFR). For cooking oil, a carbon face against a ceramic seat with a Viton or EPDM gasket is common. Verify the specific MPN's material certifications with FLOWSERVE or consult 3G Electric for application notes.

A unitized rotary seal, such as the FLOWSERVE Type 16 (SKU 1R311), has the rotating and stationary faces pre-assembled into a single cartridge. This simplifies installation and reduces the risk of face damage during handling. Standard single-spring seals (Types 21, 51, 52, 68) require separate installation of the rotating assembly and stationary seat. Unitized seals are often preferred for field replacements where precision alignment is difficult. Both designs use a single spring to maintain face contact, but the unitized version includes a built-in gland and sleeve.