What is a split mechanical seal?
A mechanical seal is a device used to contain fluid within a vessel where a rotating shaft passes through housing, or sometimes where housing rotates around a shaft. These vessels are usually pumps, mixers, agitators, grinders, etc. The purpose of a mechanical seal is to allow the shaft to rotate freely without allowing large amounts of fluid to escape.
How is a split mechanical seal different from a component or cartridge seal?
A split seal comes in two separate pieces. Unlike ordinary cartridge mechanical seals, these two pieces can be installed or removed from around the shaft without disassembling the equipment. When joined, the sealing elements are mated to create a proper seal around the shaft.
When should a split mechanical seal be used?
A common component seal replacement on a split-case pump would require removal of end bearings, motor coupling, and possibly the motor itself. These extra processes cause increased hours of labor, more downtime, and additional complexity, which in turn means increased cost. A split mechanical seal, however, can greatly decrease these deficits.
Common applications for split seals are as follows:
- Water and waste water technology
- Pulp and paper industry
- Mining industry
- Power plant technology
- Process technology
- Centrifugal pumps
- Displacement pumps
- Conveying limber to refiners with feeder screws
- Conveying pulp with stock pumps
- Pump stations for waste water treatment
- Cooling water pumps for energy generation
- Circulation of pulp and water mixtures in storage vessels
These applications and industries benefit from split seals because the equipment typically requires large amounts of time for disassembly. The use of split mechanical seals in these applications reduces install time, reduces sleeve wear, increases equipment reliability, and reduces maintenance costs.
Split seals are not recommended for applications in which potential emissions or leakage will be a threat to company personnel or to the environment. Due to how split mechanical seals are constructed, they have an increased amount of potential leak paths.
Splitex by EagleBurgmann
Splitex® seals can save you time and money
The Splitex® is made up of 2 x 2 pre-assembled halves which are simply placed around the shaft and screwed into place without the need to disassemble the pump. The seal has the same features as a non-split cartridge seal: balanced, stationary design, precision seal pre-adjustment and no contact between the springs and the product. Additionally no modification to the seal housing is needed, because the Splitex® is mounted fully on the outside. The seal is externally pressurized and comes with integrated flushing connections as a standard feature.
Features of Splitex
- Fully split single seal, 2 x 2 segments, pre-assembled
- Stationary springs
- External pressurization
- Built-in flushing connections
- Installation and wear control
- Reduced repair and downtime: 2 x 2 pre-assembled parts, which speeds up and simplifies installation because the pump does not have to be disassembled
- Long service life: Precise pre-alignment because of pre-assembled segments. Stationary springs which are protected from the product prevent clogging
- Greater flexibility during installation: no modification necessary because the seal is located outside of the stuffing box
- Dependable operation: mechanical decoupling of clamping ring (torque transmission) avoids deformation or torsional stress at the seat
- Simple monitoring of the seal during operation because of mechanical wear indicator on the seal face
- Low leakage: elimination of secondary seals eliminates leakage paths between split components
- High tolerance to shaft deflections ensured by stationary design and elastic seat mounting (gasket)
- Shaft protection: uniform torque transmission via clamping ring prevents damage caused by set screws
- Seal face: Carbon graphite antimony impregnated (A), Silicon carbide (Q6)
- Seat: Silicon carbide (Q6)
- Secondary seals: FKM (V), EPDM (E), NBR (P)
- Springs: CrNiMo steel (G)
- Metal parts (CrNiMo steel, CrNiMo cast steel (G)
Information gleaned from this article was gathered from EagleBurgmann’s Splitex documentation, which can be found here.
Other mechanical split seal information was repurposed from the engineering blog of Crane.