I. Model Meaning (Sequentially)

D631: 631 Series Two-stage Mechanical Feedback Servo Valve

K: Ex ia IIC T4/T6 Explosion-proof (Zone 0/1/2 available)

810: Flow Code → 75 L/min @ Δp=35 bar (Maximum flow rate of 631 series)

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

Sentence: K810C = Explosion-proof + 75 L/min Ultra-Large Flow + Built-in Pilot + Standard Performance

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

Rated Flow: 75 L/min (Upper limit of 631 series)

Maximum Working Pressure: 315 bar

Frequency Response (−3 dB, 90°): ≈ 45–55 Hz (Maximum flow rate, Minimum frequency response)

Step Response (100%): ≈ 28–35 ms

Hysteresis: ≤ 0.3%

Resolution: ≤ 0.1%

Zero Position Leakage: ≈ 1.1 L/min (Maximum flow rate, Highest leakage)

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

Explosion-Proof Rating: Ex ia IIC T4/T6 (Explosion-proof)

Temperature Range: −20 ℃ ~ +80 ℃

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

III. Comparison of D631K810C with K796C/K780C Table

Project  D631K810C  D631K796C  D631K780C

Rated Flow Rate  75 L/min  63 L/min  40 L/min

Frequency Response  45–55 Hz  50–60 Hz  55–65 Hz

Zero-Position Leakage  1.1 L/min  1.0 L/min  0.7–0.8 L/min

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

Typical Applications  Explosion-proof area super-large flow closed-loop  Explosion-proof area large flow closed-loop  Explosion-proof area medium-large flow closed-loop

In one sentence: K810C is the "flow ceiling" of the 631 series explosion-proof version, with the slowest dynamic response and the highest leakage; K796C is the second largest, and K780C is the medium-large size.

Four. Features and Applications Characteristics

✅ 75 L/min explosion-proof ultra-high flow rate: The 631 series has the largest flow rate, 19% higher than the 796C.

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

✅ Standard dynamic + high leakage: Cost-effective, reliable and durable.

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

Typical applications

Chemical explosion-proof ultra-high flow hydraulic station: 75 L/min actuator, closed-loop control in explosion-proof area

Large-scale execution mechanism for oil and gas platforms: Large thrust / high-speed hydraulic execution mechanism in Zone 0/1

Dust explosion-proof heavy equipment: Large-scale mixing machines / extruders for aluminum powder / flour / feed, etc., requiring explosion-proof systems with extreme flow rates

Metallurgical explosion-proof conditions: Ultra-thick plate rolling mills, large roll gap control, explosion-proof systems with extreme flow rates required