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)

796: Flow Code → 63 L/min @ Δp=35 bar (Maximum Flow of 631 Series)

C: Built-in Pilot Supply Oil, NBR Seal, Standard Zero Position

Sentence: K796C = Explosion-proof + 63 L/min Ultra-Large Flow + Built-in Pilot + Standard Performance

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

Rated Flow: 63 L/min (Maximum of 631 Series)

Maximum Working Pressure: 315 bar

Frequency Response (−3 dB, 90°): ≈ 50–60 Hz (Large Flow, Minimum Frequency Response)

Step Response (100%): ≈ 25–30 ms

Hysteresis: ≤ 0.3%

Resolution: ≤ 0.1%

Zero Position Leakage: ≈ 1.0 L/min (Maximum Flow, Highest Leakage)

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 D631K796C with K780C/K771C Table

Project D631K796C D631K780C D631K771C

Rated Flow Rate 63 L/min 40 L/min 25 L/min

Frequency Response 50–60 Hz 55–65 Hz 60–70 Hz

Zero-Position Leakage 1.0 L/min 0.7–0.8 L/min 0.6 L/min

Explosion-proof / Precautionary Measures Explosion-proof + Built-in Explosion-proof + Built-in Explosion-proof + Built-in

Typical Applications Exterior explosion-proof area with large flow rate closed-loop Exterior explosion-proof area with medium-large flow rate closed-loop Exterior explosion-proof area with medium flow rate precise closed-loop

In one sentence: K796C is the "flow ceiling" of the 631 series explosion-proof version, with the slowest dynamic response and the largest leakage; K780C is for medium-sized and large-scale applications, and K771C is for small-scale applications.

Four. Features and Applications Characteristics

✅ 63 L/min Explosion-proof Ultra-Large Flow Rate: The 631 series has the largest flow rate, 57% higher than 780C

✅ Built-in Pilot: No need for an external X port. The system is simple and easy to install

✅ Standard Dynamics + Higher Leakage: Cost-effective, reliable and durable

✅ Explosion-proof K: Directly meets Ex ia IIC T4/T6, suitable for Zone 0/1/2

Typical Applications

Chemical explosion-proof large-flow hydraulic station: 63 L/min actuator, explosion-proof zone closed-loop control

Large-scale actuators for oil and gas platforms: Zone 0/1 large-thrust / high-speed hydraulic actuators

Dust explosion-proof heavy equipment: Large-scale mixing machines / extruders for aluminum powder / flour / feed, large-scale equipment with explosion-proof requirements

Metallurgical explosion-proof conditions: Large roll gap control, thick plate rolling machines, explosion-proof systems requiring ultra-large flow rate