Ball Valve Seals in Spitzer SF/SK Silo Trailers
Ball valve seals are the wear components that determine whether a ball valve holds a tight shut-off in aluminium Spitzer SF and SK silo trailers. The seat rings and O-rings in direct contact with the ball are what guarantee a positive cut-off of bulk material or air flow and keep operating torque acceptably low. Seal wear is the most common — and most straightforward — cause of a leaking valve: replacing the seal kit is considerably cheaper and faster than replacing the complete valve.
Our catalogue includes complete ball valve seal kits comprising 2x PTFE seat rings and 2x NBR O-rings. The PTFE rings form the valve seat and the sealing surface against the ball; the NBR O-rings seal the valve body. Kits are available in DN80 and DN100, matching the standard product (goods) ball valves — Prokosch / ZR type — fitted to Spitzer silo trailers.
Standardising to two sizes with a clearly defined kit content makes part selection straightforward and repeatable. Ball valve seals are typically serviced together with the product valve and its blow-off insert as a single discharge-node overhaul, keeping the entire system leak-free without replacing expensive components.
The two-material combination is deliberate. The PTFE rings provide a smooth, hard seating surface for the ball to rotate against — offering low friction, chemical resistance, and repeatable positive closure. The NBR O-rings seal the interface between the ball housing and the valve body, eliminating leakage around the perimeter. This arrangement — a hard, low-friction PTFE seat surface combined with a flexible NBR body seal — is standard on the Prokosch (Type 420) product ball valve and the closely related ZR type, where the ball seal is PTFE and the body seal is NBR.
Components and Materials
| Kit component | Quantity | Material |
|---|---|---|
| Seat ring | 2x | PTFE (Teflon) |
| O-ring | 2x | NBR |
Kits available in DN80 and DN100.
Sizes and Types
| Size DN (mm) | Kit contents |
|---|---|
| DN80 | 2x PTFE seat ring + 2x NBR O-ring |
| DN100 | 2x PTFE seat ring + 2x NBR O-ring |
Compatibility with Spitzer Silo Trailers (SF/SK)
Ball valve seal kits are matched to the product (goods) ball valves — Prokosch / ZR type — in DN80 or DN100, as fitted to Spitzer SF and SK silo trailers. The kit content (2x PTFE ring + 2x NBR O-ring) directly corresponds to the working elements of these valves, so a replacement restores factory-level sealing without any modification to the valve body.
In practice it is worth keeping ball valve seal kits in stock alongside product valves and blow-off inserts, so that the entire discharge node can be overhauled during a planned service visit. Size selection (DN80/DN100) follows directly from the valve fitted to the trailer in question.
Common Failure Modes in Spitzer Silo Trailers
In service practice, worn PTFE seat rings typically manifest as a ball valve leaking in the closed position and increased resistance to ball rotation. Hardened or damaged NBR O-rings cause leakage at the interface between the ball housing and the valve body.
Both symptoms are normally resolved by fitting a complete seal kit (2x PTFE ring + 2x NBR O-ring) in the correct size — DN80 or DN100. If leakage persists after a fresh kit has been installed, the cause may be wear to the ball itself or the valve body, in which case the service team will assess whether a full valve replacement is warranted.
Under intensive operation with abrasive bulk materials, PTFE seat rings wear more quickly than those in air valves, because abrasive granulate or powder passes directly through the product valve node. For this reason, ball valve seal kits should be treated as a stock item held alongside product valves and blow-off inserts — their availability on the shelf reduces downtime during planned maintenance and allows the entire discharge node to be brought back to specification on-site, without waiting for parts to be sourced.
Availability and Delivery
Ball valve seal kits (2x PTFE ring + 2x NBR O-ring) in DN80 and DN100 are held in stock at PHS Magnum in Chorula near Opole and are also available for direct shipment.
- Poland — courier delivery
- DACH — delivery to Germany, Austria, and the Czech Republic
- Collection in person — Chorula near Opole, 4 km from the A4 motorway
To select the correct kit for a specific valve, contact our Spitzer service team on +48 602 716 551. Full range of services: magnumchorula.pl/en/service/.
Related Categories
- Prokosch Product Ball Valves — aluminium product ball valves, Prokosch type (Type 420) and ZR
- Segmental Ball Valves — segmental ball valves for air, ZR type (Type 500)
- Ball Valve Blow-Off Insert — DN80/DN100 blow-off inserts for Prokosch and ZR valves
- Spitzer Spare Parts Catalogue — full overview of all categories
See also: This category in the full PHS Magnum network catalogue (all makes) →
Author: Aleksy Pasternak — Managing Partner PHS Magnum, 20 years in the industry, ISO 9001:2015 internal auditor (DEKRA).
