Prokosch Bulk Discharge Ball Valves in Spitzer SF/SK Silo Trailers
Bulk discharge ball valves are the shut-off elements in the product flow path of Spitzer aluminium silo trailers (SF and SK series). Unlike air-side valves, they carry the load of abrasive granules and powders in transit, so their ball and seals are specifically rated for contact with bulk material. A serviceable discharge valve is essential for reliable shut-off and controlled product flow during unloading.
We stock aluminium bulk discharge ball valves in the Prokosch type (Type 420): body in aluminium or cast iron, chrome-plated cast iron ball, PTFE ball seal, and NBR body seal. Rated to 10 bar working pressure across a temperature range of -25 °C to 90 °C, with a DIN 28460 flange interface. We also carry the sister ZR type — the equivalent of the Prokosch 420 — with a stainless steel ball.
All bulk discharge valves are available in two bore sizes: DN80 and DN100. Standardisation to these two sizes and the DIN 28460 flange makes component selection straightforward and repeatable for any Spitzer silo trailer in the fleet. We supply matching air purge fittings and ball seal kits alongside the valves, so the complete discharge valve assembly can be sourced and serviced from a single supplier.
Specifications and Materials
| Parameter | Prokosch Type (Type 420) | ZR Type (sister) |
|---|---|---|
| Body material | aluminium or cast iron | aluminium or cast iron |
| Ball material | chrome-plated cast iron | stainless steel |
| Ball seal | PTFE (Teflon) | PTFE (Teflon) |
| Body seal | NBR | NBR |
| Working pressure | 10 bar | 10 bar |
| Temperature range | -25 °C to 90 °C | -25 °C to 90 °C |
| Flange standard | DIN 28460 | DIN 28460 |
Sizes and Types
| Bore size DN (mm) | Types |
|---|---|
| DN80 | Prokosch Type 420, ZR sister type |
| DN100 | Prokosch Type 420, ZR sister type |
Each bulk discharge valve is available in DN80 and DN100.
Compatibility with Spitzer Silo Trailers (SF/SK)
Prokosch Type 420 and ZR bulk discharge ball valves are selected to match the discharge assembly on Spitzer SF and SK silo trailers, in DN80 or DN100. The DIN 28460 flange ensures a consistent, repeatable connection. The choice between a chrome-plated cast iron ball (Prokosch 420) and a stainless steel ball (ZR) depends on the nature of the bulk material being carried and the required service life.
Matching air purge fittings (DN80/DN100, for Prokosch or ZR) and ball seal kits can be supplied alongside the valves, allowing the complete shut-off assembly to be built up and maintained without mixing components from different systems.
Common Faults in Spitzer Silo Trailers
In service practice, the most common fault on a bulk discharge ball valve is wear to the PTFE ball seal and the NBR body seal — resulting in leakage and product weeping in the closed position. A second typical issue is stiffness or seizure of the ball, caused by abrasive material deposits and wear to the ball surface (chrome-plated cast iron).
In both cases, the remedy is a ball seal kit (full set of PTFE rings and NBR O-rings) sized for DN80 or DN100; where ball wear is advanced, either the ball element or the complete valve should be replaced. The choice between a chrome-plated cast iron ball and a stainless steel ball (ZR type) is worth considering in relation to the abrasiveness of the material being transported.
Availability and Delivery
Prokosch Type 420 and ZR bulk discharge ball valves in DN80 and DN100 are dispatched from PHS Magnum stock in Chorula near Opole, or supplied via direct delivery.
- Poland — courier delivery
- DACH — delivery to Germany, Austria, and the Czech Republic
- Collection — PHS Magnum warehouse, Chorula near Opole, 4 km from the A4 motorway
For valve, air purge, and seal kit selection: Spitzer service team, tel. +48 602 716 551. Full scope of services: magnumchorula.pl/en/service/.
Related Categories
- Segmental Ball Valves — segmental air-side ball valves, ZR type (Type 500)
- Ball Valve Air Purge — DN80/DN100 air purge fittings for Prokosch and ZR valves
- Ball Seal Kits — ball seal kits (PTFE + NBR)
- Spitzer Spare Parts Catalogue — full catalogue by category
See also: This category in the full PHS Magnum network catalogue (all brands) →
Author: Aleksy Pasternak — Managing Partner, PHS Magnum, 20 years in the industry, ISO 9001:2015 internal auditor (DEKRA).
