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) Moog Inc.

780: Flow Code → 40 L/min @ Δp=35 bar

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

K (suffix): Explosion-proof Special Coil + Reverse Polarity Protection + Explosion-proof Sealing Connector + Low Power Consumption Design

Sentence: K780CK = K780C + Full Enhancement of Intrinsically Safe Electrical Components

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

Rated Flow: 40 L/min Moog Inc.

Maximum Working Pressure: 315 bar

Frequency Response (−3 dB, 90°): 55–65 Hz

Step Response (100%): 22–28 ms

Hysteresis / Resolution: ≤ 0.3% / ≤ 0.1%

Zero Position Leakage: ≈ 0.7–0.8 L/min

Pilot Supply Oil: Built-in (P port takes oil) Moog Inc.

Explosion-Proof Rating: Ex ia IIC T4/T6 (Intrinsic Safety, Oil/Gas / Dust Explosion Zone) Moog Inc.

Coil Characteristics (K suffix):

Rated Current: ±40 mA (Intrinsic Safety Low Power Consumption) Moog Inc.

Coil Resistance: High Resistance Explosion-proof Type (Energy Limitation)

Insulation Class: H Class (High Temperature Explosion Safety)

Protection: Reverse Polarity, Surge Suppression, Explosion-proof Sealing Connector

Temperature Range: −20 ℃ ~ +80 ℃ Moog Inc.

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

III. Comparison of K780CK with K780C / K771CK

1) D631K780CK vs D631K780C

Same: 40 L/min, Explosion-proof Valve Body, Built-in Pilot, Pressure / Frequency Response / Leakage Consistent

Different (CK has more):

✅ Intrinsic Safety Explosion-proof Special Coil (Low Power Consumption, High Resistance, Compatible with Safety Transmitter)

✅ Reverse Polarity Protection (Explosion-proof Area Wiring Not Afraid of Reverse Connection)

✅ Explosion-proof Sealing Connector (Ex ia Certification Complete)

✅ Surge Suppression (More Stable Explosion-proof Circuit)

2) K780CK vs K771CK (Most Common Comparison) Table

Project  D631K780CK  D631K771CK

Rated Flow Rate  40 L/min  25 L/min

Frequency Response  55–65 Hz  60–70 Hz

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

Explosion-proof / Coil  Explosion-proof + Intrinsic Safety + Explosion-proof Coil + Reverse Polarity  Intrinsic Safety + Explosion-proof Coil + Reverse Polarity

Applicable Scenarios  Large Flow Rate Closed-loop in Explosion-proof Area  Precise Closed-loop in Explosion-proof Area

One sentence: K780CK is the top-of-the-line explosion-proof electrical device for high flow rates; K771CK is the top-of-the-line explosion-proof electrical device for medium flow rates.

Four. Features and Applications Characteristics

✅ 40 L/min explosion-proof high-flow + Safety Certification (Ex ia IIC T4/T6) Moog Inc.

✅ Built-in pilot + explosion-proof coil + reverse polarity protection: Simple system, fault-tolerant explosion-proof wiring

✅ Standard dynamics + standard leakage: Moderate cost, reliable and durable

✅ Low-power explosion-proof coil: Directly compatible with safety barriers, no need for explosion-proof relays

Typical applications

Chemical explosion-proof hydraulic station: 40 L/min actuator, safety-critical closed loop

Oil and gas platforms / wellhead control: Zone 0/1 high-flow hydraulic actuator

Dust explosion-proof environment: Aluminum powder / flour / feed equipment, 40 L/min precise control

Metallurgical explosion-proof conditions: Roll gap / tension control, high-flow closed-loop in explosion-proof area