I. Explanation of Model Numbers

D631: 631 Series Two-stage Mechanical Feedback Servo Valve

Z: Non-explosion-proof, standard industrial environment

824: Flow code 80 L/min (Δp = 35 bar); Last digit 4 = High leakage valve core, High dynamic response

C: Internal pilot + FPM (fluorine rubber) seal (high-temperature type)

Sentence: Z824C = 80L/min high flow + Internal lead-in without external connection + FPM high-temperature seal + High leakage and high dynamic response type

II. Core Parameters (Δp = 35 bar)

Rated Flow: 80 L/min

Maximum Pressure: 315 bar

Frequency Response (−3dB/90°): 50–60 Hz (maximum dynamic in 80L)

Step Response: 25–30 ms (fastest)

Hysteresis: ≤0.3%

Resolution: ≤0.1%

Zero Leakage: ≈0.80 L/min (high leakage, type 4)

Pilot Method: Internal pilot (no X port required)

Sealing / Temperature: FPM (−20 to +120°C)

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

III. 824C / 820C / 803C The Three Brothers (Internal Lead-in Comparison for 80L) Table

Parameters: D631Z824C, D631Z820C, D631Z803C

Flow rate: 80 L/min, 80 L/min, 80 L/min

Pilot: Internal, Internal, Internal

Leakage type: 4 = High leakage (≈0.80 L/min), 0 = Standard leakage (≈0.50 L/min), 3 = Low leakage (≈0.30 L/min)

Frequency response: 50–60 Hz (maximum), 40–50 Hz, 40–50 Hz

Step response: 25–30 ms (fastest), 35–40 ms, 35–40 ms

Power consumption / Heat generation: High, Medium, Low

Price: Mid-high (dynamic model), Economy (general model), Mid-high (energy-saving model)

Applicability: High-frequency, rapid reversing, dynamic priority; Regular continuous operation; Long-term standby, energy-saving priority

In one sentence: 824C for high leakage and high dynamic; 820C for balance; 803C for low leakage and energy-saving

Four. Application scenarios (Z824C)

High-speed heavy-duty presses, rapid forging machines, high-speed injection molding injection / locking

High-speed metallurgical rolling, dynamic synchronous control, high-frequency cylinder movement

High temperature (≤120℃), ordinary hydraulic oil, pursuit of fastest response

Internal pilot, dynamic performance priority, energy consumption secondary closed-loop system