One warehouse for multi-brand fleets
PHS Magnum has been servicing silo trailer fleets from various manufacturers since 1990 — and it is precisely this multi-brand approach that sets the hub’s offering apart from a single factory service centre. Ball seals are a typical consumable that wears the same way on a Spitzer, Feldbinder or Kässbohrer trailer, because what matters is not the logo on the tank but the size and design of the ball valve itself. That is why we run a single, shared warehouse of seal kits, from which we match the part to any trailer in operation.
The ball seal is the working element of the product ball valve (Prokosch / ZR type) and related fittings. It is not a structural part of the trailer but a consumable of the discharge assembly — a component replaced on a planned basis when the valve loses tightness. From a mixed-fleet perspective, this means one stock item covering many brands instead of separate catalogues for each manufacturer.
Technical specification — PTFE + NBR kit
The ball seal kit has a fixed, repeatable composition regardless of the trailer brand:
| Element | Qty per kit | Material | Function in the valve |
|---|---|---|---|
| Ring | 2 pcs | PTFE | ball seats, sealing and sliding surface |
| O-ring | 2 pcs | NBR | valve body sealing |
The choice of two different materials follows from two different jobs in the valve. The PTFE rings act as the seats in which the ball sits and rotates — PTFE provides a smooth sliding surface, low rotational resistance and chemical resistance to the transported media. It is on these rings that the actual flow shut-off in the closed position takes place. The NBR O-rings, in turn, work at the valve body joints: nitrile rubber retains the elasticity needed to seal the housing connections and blocks material seepage around the circumference. A hard, sliding PTFE surface plus an elastic NBR body seal is the classic arrangement of Prokosch (Type 420) product ball valves and the sister ZR type.
We offer kits in two sizes corresponding to the typical ball valve diameters in silo trailer discharge lines:
- DN80
- DN100
The kit configuration (2x PTFE ring + 2x NBR O-ring) is fixed for a given size, so when ordering it is enough to state the valve’s DN. There is no need to dismantle or send in the whole valve — the size unambiguously determines the matching kit. Where the valve specification and the medium require it, we confirm the seal version individually for the specific valve model; the PTFE + NBR combination remains the standard for the kit described here.
From a fleet maintenance perspective, distinguishing the two materials has practical significance. The PTFE ring wears primarily by abrasion — from contact with the flowing bulk material — and it is usually the first to lose the ability to close tightly. The NBR O-ring degrades mainly with time and temperature, losing the elasticity needed to maintain clamping force on the body. Since both wear paths lead to the same fault — a leaking valve — the kit is replaced as a whole, not element by element. A complete set guarantees that after refurbishment no sealing interface is left riding on an old, worn component.
Compatibility with silo trailer brands
Because the seal is fitted inside the ball valve, compatibility is determined by size (DN80/DN100), not by the trailer brand or model. The same Prokosch / ZR type product ball valves recur in the discharge lines of silo trailers from various European manufacturers, which makes the kit universal within a given diameter:
| Silo trailer brand | Typical series | Notes |
|---|---|---|
| Spitzer | SF, SK | non-tipping SF series and tipping SK series |
| Feldbinder | EUT, KIP | non-tipping EUT line and tipping KIP silo |
| Kässbohrer | K.SSK, K.SSL | silo trailers for bulk materials |
We also service ball valves on trailers from other European silo trailer manufacturers — here matching is done directly by valve size (DN80/DN100) and fitting type, without tying the kit to specific models. In every case the principle stays the same: the buyer states the valve diameter rather than hunting for a part “by brand”. That is the essence of the multi-brand approach — one seal kit covers a mixed fleet.
Warehouse in Chorula
Ball seal kits in DN80 and DN100 are kept in stock at the PHS Magnum warehouse in Chorula near Opole — 4 km from the A4 motorway junction, approx. 180 km from the German border. The location on the A4 corridor shortens delivery times both to the Polish market and to customers across the EU, which matters for consumables ordered ahead of a planned inspection.
We treat ball seals as a stock item kept together with product ball valves and their blow-off units, so that during discharge assembly service the tightness of the whole system can be restored in a single visit. Off-the-shelf availability of the kit shortens trailer downtime — a leaking valve does not have to stall the discharge cycle while a part is sourced. A common operating mistake is trying to re-seal the valve by tightening it harder instead of replacing the seats; with worn PTFE rings, increasing the clamping force does not restore tightness — it only raises the ball’s rotational resistance and accelerates wear. The correct response to a leaking valve is to dismantle it and fit a new seal kit — a short operation that avoids the more expensive replacement of the entire ball valve.
We also carry out valve refurbishment with seal replacement as part of PHS Magnum silo trailer service, including alongside TDT inspections. For availability and pricing — ask for a quotation.
Specialist portals
For single-brand fleets we run dedicated parts portals where the same category is described from the perspective of a specific manufacturer:
- Ball seal kits for Spitzer silo trailers (SF/SK series): spitzer.pl/czesci-zamienne/uszczelnienia-kuli/
- Ball seal kits for Feldbinder silo trailers (EUT/KIP series): feldbinder.pl/czesci-zamienne/uszczelnienia-kuli/
Whichever portal you use, the kit is the same (2x PTFE ring + 2x NBR O-ring, DN80/DN100) — only the operational context described for the given brand differs.
Related categories
- Prokosch product ball valves — aluminium product ball valves, Prokosch type (Type 420) and ZR.
- PTFE-seated ball valves — valves with PTFE seats for the discharge line.
- Segment ball valves — segment ball valves for air, ZR type (Type 500).
- Ball valve blow-off — DN80/DN100 blow-off units for Prokosch and ZR ball valves.
- See also: spare parts catalogue, PHS Magnum silo trailer service.
Author: Aleksy Pasternak — Managing Partner at PHS Magnum, 20 years in the industry, ISO 9001:2015 internal auditor (DEKRA).
