I. Model Meaning (Sequentially)

D631: 631 Series Two-stage Mechanical Feedback Servo Valve

K: Ex ia IIC T4/T6 Intrinsically Safe (Zone 0/1/2 Available)

811: Flow Code → 75 L/min @ Δp=35 bar; Last digit 1 = Zero Position Ultra-Low Leakage

C: Built-in Pilot Supply Oil, NBR Seal, Zero Position Optimization (Low Leakage)

In one sentence: K811C = Explosion-proof + 75 L/min Maximum Flow + Built-in Pilot + Zero Position Ultra-Low Leakage

II. Core Parameters (Δp=35 bar / Each Side)

Rated Flow: 75 L/min (Upper Limit of 631 Series) Moog Inc.

Maximum Working Pressure: 315 bar Moog Inc.

Frequency Response (−3 dB, 90°): ≈ 45–55 Hz (High Flow, Low Frequency Response)

Step Response (100%): ≈ 28–35 ms

Hysteresis: ≤ 0.3%

Resolution: ≤ 0.1%

Zero Position Leakage: ≈ 0.6 L/min (45% lower than 810C, Close to Medium Flow Valve Level)

Pilot Supply Oil: Built-in (Oil is taken from Port P)

Explosion-proof Grade: Ex ia IIC T4/T6 (Intrinsically Safe)

Temperature Range: −20 ℃ ~ +80 ℃

Filter Requirements: NAS 6–7 / ISO 4406 <14/11

III. Comparison of D631K811C and K810C/K796C Table

Project D631K811C D631K810C D631K796C

Rated Flow Rate 75 L/min 75 L/min 63 L/min

Frequency Response 45–55 Hz 45–55 Hz 50–60 Hz

Zero-Position Leakage ≈0.6 L/min ≈1.1 L/min ≈1.0 L/min

Explosion-proof / Pre-charge Explosion-proof + Built-in Explosion-proof + Built-in Explosion-proof + Built-in

Zero-Position Characteristics Ultra-low leakage, optimized zero position Standard leakage Standard leakage

Typical Applications Explosion-proof zone 75 L/min + low-power closed-loop Explosion-proof zone 75 L/min standard closed-loop Explosion-proof zone 63 L/min high-flow closed-loop

In one sentence: K811C is a "low-leakage specialized version" of the 75 L/min explosion-proof model, with the same flow rate as 810C and leakage close to 771C, balancing high flow rate and low energy consumption.

Four. Features and Applications Characteristics

✅ Explosion-proof maximum flow rate of 75 L/min: 631 series from Moog Inc.

✅ Built-in pilot: No need for external X port, the system is simple and easy to install. From Moog Inc.

✅ Ultra-low zero-point leakage (0.6 L/min): 45% lower than 810C, significantly reducing standby energy consumption and less heat generation.

✅ Intrinsically safe K: Directly meets Ex ia IIC T4/T6 standards, suitable for Zone 0/1/2.

Typical applications

Chemical explosion-proof ultra-large flow energy-saving hydraulic station: 75 L/min level actuator, long-term standby / low-load operation

Oil and gas platform super-large low-power actuators: Zone 0/1 large thrust / high speed + low leakage requirements

Dust explosion-proof heavy equipment: Large-scale aluminum powder / flour mixing machines, extruders, requiring large flow + low energy consumption

Metallurgical explosion-proof energy-saving conditions: Ultra-thick plate rolling mills, large roll gap control, balancing extreme flow rate and low leakage