Introduction
Pneumatic discharge in Feldbinder silo trailers — whether the horizontal, non-tipping EUT series or the pressure-tipping KIP (Kippsilo) — relies on distributing compressed air through a dedicated pressure circuit. The components that control this airflow are PTFE-sealed ball valves. They are shut-off devices: full open or full closed with a 90° turn of the handle, without throttling.
In Feldbinder silo trailers, ball valves operate in a demanding environment: sub-zero mornings on DACH routes (hence the -40°C lower limit), warm compressed air from the onboard compressor, and condensate. PTFE seals handle these conditions significantly better than elastomers, which is why PTFE is the default sealing material here. For the most heavily loaded nodes — high-pressure branches and circuits running at elevated temperatures — Feldbinder specialists reach for the heavy-duty V4A stainless steel version, rated to 63 bar and 180°C.
PHS Magnum in Chorula near Opole stocks PTFE ball valves in both versions, each supplied with a material certificate. The full parts catalogue is available at /en/spare-parts/, and the scope of service work is described on magnumchorula.pl/en/service/.
Specification and Materials
PTFE-sealed air ball valves are available in two versions: standard and heavy-duty stainless steel.
Standard Version
| Component | Material / value |
|---|---|
| Body | Nickel-plated brass |
| Ball | Chromium-plated steel |
| Seal | PTFE (polytetrafluoroethylene) |
| Handle lock | None |
| Operating temperature | -40°C to 120°C |
Heavy-Duty Version (direct supply)
| Parameter | Value |
|---|---|
| Material | Acid-resistant stainless steel V4A |
| Working pressure | Up to 63 bar |
| Operating temperature | Up to 180°C |
The difference between the two versions goes beyond working range. The nickel-plated brass of the standard version is lightweight and cost-effective, but once its nickel coating is damaged, the body is exposed to condensate attack. The V4A stainless steel of the heavy-duty version is heavier and more expensive, but withstands both higher pressures and chemically aggressive media — making it the right choice for the most demanding circuit nodes. The PTFE seal in both versions ensures low rotational resistance and a reliable shut-off; PTFE does not become brittle at low temperatures and does not soften within the normal operating range of the installation.
Sizes and Types
The size table for PTFE ball valves covers four parameters: DN bore size, female thread, overall length, and standard working pressure:
| DN size (mm) | Female thread (inches) | Length (mm) | Working pressure (bar) |
|---|---|---|---|
| 6 | 1/4 | 44.4 | 50 |
| 10 | 3/8 | 44.4 | 50 |
| 15 | 1/2 | 50.5 | 50 |
| 20 | 3/4 | 57.5 | 40 |
| 25 | 1 | 70 | 40 |
| 32 | 1 1/4 | 80.5 | 30 |
| 40 | 1 1/2 | 94.5 | 30 |
| 50 | 2 | 112.5 | 25 |
| 64 | 2 1/2 | 135 | 15 |
| 80 | 3 | 158 | 16 |
All sizes listed above are also available in the heavy-duty V4A stainless steel version (direct supply), rated to 63 bar and 180°C. The correct size is matched to the thread, length, and pressure of the specific circuit.
To select the right valve, four pieces of information are needed: the DN bore diameter, the female thread size in inches, the required working pressure, and the operating temperature range. If a circuit runs above 120°C or close to the upper pressure limit, the correct choice from the outset is the heavy-duty V4A version — this avoids premature degradation of a standard valve. For typical aeration lines and discharge branches, the standard version (nickel-plated brass, chromium ball, PTFE) is a proven and adequate solution.
Compatibility with Feldbinder Silo Trailers (EUT / KIP)
In the EUT range (horizontal, non-tipping tank with pneumatic discharge), air ball valves isolate and open compressed-air flow in the aeration lines and branches leading to the discharge nozzles. In multi-compartment versions, each compartment has its own branch — and therefore its own shut-off valves — with the total count increasing with tank configuration.
In the KIP (Kippsilo) range — the pressure-tipping silo trailer used for bulk materials with poor flow characteristics — ball valves perform the same isolation function within the pressure circuits. Because the correct valve selection (DN, thread, pressure, temperature) depends on the circuit parameters rather than the trailer type, the same catalogue covers both designs. For nodes with elevated pressure or temperature requirements, the heavy-duty V4A version applies.
Common Failure Modes in Feldbinder Trailers
In practice, the most frequent issues with air ball valves in Feldbinder silo trailers are:
- Seized ball — contamination or condensate on the chromium ball surface makes the handle stiff; cleaning usually restores normal operation.
- PTFE seal leakage — under intensive use the PTFE seal loses contact pressure; the seal may be replaceable, but in most cases the valve should be replaced as a unit.
- Body corrosion — on standard versions (nickel-plated brass), surface corrosion appears once the nickel coating is breached; in chemically aggressive environments or food-grade applications, the stainless steel version is the appropriate choice.
- Operation beyond temperature range — exceeding 120°C on a standard valve accelerates degradation; the correct solution for such circuits is the heavy-duty V4A version (rated to 180°C).
Diagnosis begins with checking handle rotation and testing for leaks in the closed position. If the ball is worn or the seal cannot be brought back into adequate contact, the entire valve is replaced.
Feldbinder’s design adds specific context here. In a horizontal multi-compartment EUT, the number of shut-off valves increases with tank complexity — during a trailer refurbishment, valves must be inventoried compartment by compartment, since wear is not uniform across the installation. In food-grade EUT versions (316L stainless), particular care is taken to ensure that replacement valves and their seals introduce no foreign material into the hygienic path. In the tipping KIP silo, where the tank operates at varying angles, special attention is paid to the security of the handle position and the clarity of the open/closed indication — with the silo raised, a valve position error is harder to correct mid-discharge.
One structural limitation is worth noting: these valves have no handle lock. This means the open or closed position is determined solely by handle orientation, with no mechanical latching. In service practice, we verify that the handle is securely fitted and gives a clear indication of valve state — a loose or damaged handle makes operation awkward and can lead to errors during discharge. Regular draining of condensate from the compressed-air system noticeably extends the service life of both the chromium ball and the PTFE seal.
Availability and Delivery
- Stock in Chorula near Opole: PTFE ball valves in the standard version — common sizes available immediately.
- 24–48 hours: most standard catalogue items.
- Direct supply: heavy-duty V4A version (up to 63 bar / 180°C) and non-standard sizes.
- Shipping: courier (PL), GLS/DHL (DACH), EU VAT invoice.
Every delivery includes a material certificate. Specification and size selection are handled as part of PHS Magnum service.
Related Categories
- Segment Ball Valves Type ZR
- Prokosch Product Ball Valves
- Gestra RV Disc Check Valves — Non-return valves for discharge pressure lines.
- Pneumatic Hoses
- Full catalogue: /en/spare-parts/
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, internal ISO 9001:2015 auditor (DEKRA).
