I. Model Meaning (Sequentially)

D631: 631 Series Two-stage Mechanical Feedback Servo Valve

Z: Standard Non-Explosion-proof Type (General Industrial Environment)

341: Flow Code → 34 L/min @ Δp = 35 bar; Last Digit 1 = Standard Zero Position Leakage

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

In one sentence: Z341C = Non-Explosion-proof + 34 L/min Medium-High Flow + Built-in Pilot + Standard Leakage

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

Rated Flow: 34 L/min

Maximum Working Pressure: 315 bar

Frequency Response (−3 dB, 90°): ≈ 55–65 Hz (Typical Value for 34 L/min Class)

Step Response (100%): ≈ 25–30 ms

Hysteresis: ≤ 0.3%

Resolution: ≤ 0.1%

Zero Position Leakage: ≈ 0.55 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 D631Z341C with Z272C/Z273C (Flow Upgrade) Table

Project D631Z341C (34 L/min) D631Z272C (27 L/min standard) D631Z273C (27 L/min low leakage)

Rated Flow Rate 34 L/min 27 L/min 27 L/min

Frequency Response 55–65 Hz 65–75 Hz 65–75 Hz

Zero-Position Leakage ≈0.55 L/min ≈0.45 L/min ≈0.25 L/min

Applicable Load Medium-High Flow, Large Cylinder Diameter Regular Flow, Standard Cylinder Diameter Regular Flow, Long-term Standby

Price Basis + 15% Basis Basis + 10%

In one sentence: Z341C is a 27 L/min upgraded model with a 25% increase in flow rate, a slightly reduced frequency response, a slightly increased leakage, and an increased price. It is suitable for larger actuators.

Four. Features and Applications Characteristics

✅ 34 L/min high-flow mode: The 631 series covers 27→34→40→63→75 L/min. 34 is the main upgraded mode.

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

✅ Mature two-stage structure: Mechanical feedback, double nozzle baffle, high reliability, strong anti-contamination ability.

✅ Non-explosion-proof Z-type: Suitable for ordinary industrial environments, with lower cost than explosion-proof K-type.

Typical applications

Closed-loop control of medium-high flow: Large-tonnage presses, injection molding machine clamping / injection, machine spindle drive

Non-explosion-proof large actuators: 34 L/min hydraulic cylinder / motor, need to balance flow and response

Metallurgy / papermaking / printing (non-explosion-proof section): Large-diameter roller tension control, synchronous drive, press-down system

Testing equipment: Large-load material testing machine, high-frequency vibration table (requiring medium-high flow)