ARC & Matrix Valves — Overview
The KSB MIL 90000 and 91000 series represent the most advanced control valve solutions in the KSB portfolio, engineered for critical and severe service applications in power plants, petrochemical facilities, and high-pressure systems. These valves combine automatic recirculation protection, multi-stage pressure reduction, and anti-cavitation technologies to protect high-value rotating equipment while ensuring stable operation under extreme conditions.
Product Range
MIL 90000 — Automatic Recirculation Valve (ARV)
The MIL 90000 ARV protects centrifugal pumps from low-flow damage, overheating, and cavitation — automatically and without any external power, controllers, or instrumentation. It integrates a check valve (main flow path) and a multi-stage bypass control valve in a single body.
How It Works
At high flow, the main check valve is fully open and the bypass is closed. As flow reduces, the bypass opens proportionally to maintain minimum continuous flow. At minimum flow, the main valve closes and full flow passes through the multi-stage bypass back to the suction source. The entire operation is driven by flow energy alone.
MIL 91000 — Matrix Series Severe Service Control Valve
The Matrix series uses a revolutionary multi-stage, multi-path trim design where fluid passes through a matrix-like cage system. Pressure and velocity are reduced gradually across up to 50 individual stages through tortuous 3D flow paths with expanding passages. This achieves a pressure recovery factor up to 0.999 (near zero recovery), virtually eliminating cavitation, noise, and vibration even at extreme pressure drops up to 400 bar.
Technical Specifications
| Parameter | MIL 90000 ARV | MIL 91000 Matrix |
|---|---|---|
| Function | Pump recirculation protection | Severe service flow control |
| Operating Principle | Self-operating (flow-controlled) | Actuated control valve |
| Size Range | 1.5–12" | Model dependent |
| Pressure Class | ANSI 150–2500 / PN 40–400 | ANSI 150–2500 |
| Max ΔP | Up to 400 bar | Up to 400 bar |
| Temperature Range | -29°C to 260°C | -29°C to 566°C |
| Trim Design | Multi-stage bypass | Multi-stage, multi-path (up to 50 stages) |
| Pressure Recovery | Multi-stage reduction | FL up to 0.999 (near zero) |
| Body Material | Forged A105 (CS), alloy/SS on request | CS / Alloy Steel / SS |
| Trim Material | Hard-faced stainless steel | Hardened martensitic SS cage stack |
| Seat | Hard-faced metal, Leakage Class IV | Metal seated, quick-change |
| End Connection | Flanged / Butt weld | Flanged / Butt weld |
| Design Standard | ASME B16.34 | ASME B16.34 |
| Rangeability | N/A (self-modulating) | ~100:1 |
| Actuation | Self-operating (no actuator) | Pneumatic / Piston / Electric |
Critical Applications
Boiler Feed Pump Recirculation
The primary application for the MIL 90000 ARV. Protects BFP from low-flow damage during load variations. Handles pressure drops up to 400 bar. Self-operating without instrumentation — essential for plant safety.
HP Steam Letdown
MIL 91000 Matrix for high-pressure steam pressure reduction. Handles temperatures up to 540°C, high expansion ratios, and extreme noise potential. Requires multi-stage trim and special metallurgy (F91/C12A).
Startup Feed Control
Handles extreme ΔP during plant startup when system pressures are rapidly changing. Requires high rangeability and cavitation resistance. MIL 91000 Matrix with multi-stage trim.
Attemperator Spray Control
Controls steam temperature by regulating spray water injection. Requires precise control with wide rangeability across varying load conditions. Matrix trim provides stable, cavitation-free operation.
Soot Blower Pressure Control
Controls high-pressure steam jets for boiler tube cleaning. Must handle thermal cycling and pressure surges during soot blowing sequences. Multi-stage trim protects against erosion.
Pump Test Loop
Simulates extreme operating conditions for pump testing facilities. Very high pressure drops (~380 bar) require multi-stage energy dissipation. MIL 91000 Matrix is proven in pump test loops globally.
Key Design Features
- Self-operating ARV (90000) requires no external power, controllers, or instrumentation — operates purely on flow energy
- Multi-stage Matrix trim (91000) divides total ΔP across up to 50 individual stages, keeping local pressure above vapor pressure at every point
- Pressure recovery factor up to 0.999 — virtually zero pressure recovery eliminates cavitation
- Tortuous 3D flow paths with expanding passages dissipate energy through controlled friction, not destructive turbulence
- Hardened martensitic stainless steel cage stack construction for erosion resistance in severe service
- Flow-to-open design (91000) provides inherent dynamic stability under varying operating conditions
- Quick-change metal seat design allows trim replacement without body removal
- Special metallurgy available: F91, C12A alloy steel for supercritical and ultra-supercritical power plant applications
- Proven in supercritical power plants handling the most demanding pressure and temperature conditions