I. Model Meaning (Sequentially)

D631: 631 Series Two-stage Mechanical Feedback Servo Valve

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

359: Flow Code → 35 L/min @ Δp=35 bar; The last digit 9 = Special Customization (Low Leakage + Zero-Position Fine-Tuning / Special Gain)

C: Built-in Pilot Supply Oil, NBR Seal, Low Leakage Valve Core

In one sentence: Z359C = Non-Explosion-proof + 35 L/min Medium-High Flow + Built-in Pilot + Low Leakage + Special Zero-Position Customization

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

Rated Flow: 35 L/min (Slightly higher than 341C, Close to the Lower Limit of 400C)

Maximum Working Pressure: 315 bar

Frequency Response (−3 dB, 90°): ≈ 55–65 Hz (Equivalent to 341C)

Step Response (100%): ≈ 25–30 ms

Hysteresis: ≤ 0.3%

Resolution: ≤ 0.1%

Zero-Position Leakage: ≈ 0.30 L/min (About 45% lower than 341C, Close to the Level of 273C)

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 D631Z359C with 341C/273C (Special Customization Version) Table

Project D631Z359C (35 L/min Custom Low Leakage) D631Z341C (34 L/min Standard) D631Z273C (27 L/min Low Leakage)

Rated Flow Rate 35 L/min 34 L/min 27 L/min

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

Zero-Position Leakage ≈0.30 L/min (Low Leakage + Custom) ≈0.55 L/min (Standard) ≈0.25 L/min (Low Leakage Base)

Custom Features ✅ Low Leakage + Zero Position / Gain Fine-Tuning ❌ Standard Configuration ❌ Only Low Leakage

Price Baseline + 20% (Custom Premium) Baseline Baseline + 10%

In one sentence: Z359C is a "low leakage + special customized version" of the 34 L/min level: slightly increased flow rate, significantly reduced leakage, with zero-position customization, and price increase, suitable for energy-saving + high-precision dual requirements.

Four. Features and Applications Characteristics

✅ 35 L/min high-medium flow rate + ultra-low leakage: Balances high flow rate and energy saving, leakage close to 273C

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

✅ Special customization (9): Zero gain/offset fine-tuning, low leakage optimization, suitable for high-precision closed-loop

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

Typical applications

High-medium flow rate + low energy consumption closed-loop: Large-tonnage presses, injection molding machine clamping / injection (long-term standby)

High-precision large actuators: 35 L/min level oil cylinder / motor, requires low leakage + zero position stability

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

Testing equipment: Large-load material testing machine, high-frequency vibration table (require both flow and precision)