I. Model Meaning (Sequentially)

D631: 631 Series Two-stage Mechanical Feedback Servo Valve

Z: Standard Type / Special Non-Explosion-proof (Different from K Explosion-proof Series, for ordinary industrial environments)

272: Flow Code → 27 L/min @ Δp=35 bar; The last digit 2 = Standard Zero Position Leakage

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

In one sentence: Z272C = Non-Explosion-proof + 27 L/min Middle Flow + Built-in Pilot + Standard Leakage

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

Rated Flow: 27 L/min (Main Flow Rate in 631 Series)

Maximum Working Pressure: 315 bar

Frequency Response (−3 dB, 90°): ≈ 65–75 Hz (Medium Flow, Excellent Dynamics)

Step Response (100%): ≈ 20–25 ms

Hysteresis: ≤ 0.3%

Resolution: ≤ 0.1%

Zero Position Leakage: ≈ 0.45 L/min (Standard Level)

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

Explosion-proof Grade: None (Z = Non-Explosion-proof)

Temperature Range: −20 ℃ ~ +80 ℃

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

III. Comparison of D631Z272C with K Series (Explosion-proof)

Table

Project D631Z272C (non-explosion-proof) D631K272C (explosion-proof, optional)

Rated Flow Rate 27 L/min 27 L/min

Frequency Response 65–75 Hz 60–70 Hz (slightly lower for explosion-proof)

Zero-Position Leakage 0.45 L/min 0.5 L/min

Explosion-proof / Precautionary Measures Non-explosion-proof + Built-in Ex ia IIC T4/T6 + Built-in

Applicable Areas General industrial areas (non-explosion-proof) Zone 0/1/2 explosion-proof areas

Price Baseline Price (low) 20–30% higher than Z-type

In one sentence: D272C is the 27 L/min non-explosion-proof main product, with good dynamics, low leakage, and reasonable price; K272C is the explosion-proof version with the same flow rate, with slightly reduced dynamics and a higher price.

Four. Features and Applications Characteristics

✅ 27 L/min High Flow Standard: The most cost-effective and widely-used flow specification in the 631 series

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

✅ High Dynamic Response (65–75 Hz): Excellent frequency response in the medium flow range, suitable for high-speed closed-loop control

✅ Non-explosion-proof Z-type: Specifically designed for ordinary industrial environments, with low cost and high reliability

Typical Applications

General industrial hydraulic stations: Injection molding machines, machine tools, presses, closed-loop control of automated production lines

High-speed non-explosion-proof actuators: 27 L/min type cylinders/motors, requiring high dynamics and low leakage

Testing equipment and laboratories: Material testing machines, vibration tables, precise displacement control

Metallurgy / Papermaking / Printing (non-explosion-proof section): Roll gap control, tension control, synchronization control