I. Model Breakdown Explanation (D633-320B)

D633: D633 Series Direct Acting Servo Valve (DDV), NG6 (03) Installation Surface

320:

3: Flow Code → 25 L/min (Δp = 35 bar)

2: Electronic / Frequency Response → High Frequency Response (120–150 Hz), Analog Input, Position Closed Loop

0: Y Port / Seal → No Y Port (T Port Low Pressure ≤ 50 bar), NBR Seal, −20 to +80°C

B: Standard Type, No Special Coating, Standard Voltage Version

In one sentence: D633-320B = NG6 + 25 L/min@35 bar + 350 bar (P/A/B) + Direct Acting without Pilot + 120–150 Hz High Frequency Response + No Y Port (T Port Low Pressure) + NBR Seal

II. Core Parameters (Δp = 35 bar)

Rated Flow: 25 L/min (For D633 Series Low Flow High Frequency Models)

Maximum Pressure:

P/A/B: 350 bar

T Port: ≤ 50 bar (No Y Port)

Hysteresis: < 0.2%

Resolution: < 0.1%

Frequency Response (±100%): 120–150 Hz (High Frequency Gear)

Step Response: ≈ 8 ms

Zero Position Leakage: ≈ 0.3 L/min (210 bar)

Seal / Temperature: NBR (−20 to +80°C)

Drive: 24VDC, ±10V or 4–20mA

Filter: ISO 4406 15/12

Features: No Pilot Hole, Extremely Anti-Pollution, Independent of Dynamic and Pressure, Spring Restored after Power Off, No Y Port Low Pressure Return Oil, Low Flow High Frequency Dynamic, Suitable for High Precision High Frequency Testing

III. Comparison of D633-320B with 317B/318B (Key Differences) Table

Project D633-317B D633-318B D633-320B

Flow rate 40 L/min 40 L/min 25 L/min

Frequency response 60–90 Hz 60–90 Hz 120–150 Hz

Y port No (T≤50bar) Yes (T=350bar) No (T≤50bar)

Sealing NBR 80℃ NBR 80℃ NBR 80℃

Positioning Middle flow standard dynamic Middle flow standard dynamic with high-pressure return oil Small flow high-frequency dynamic low-pressure return oil

Sentence: 320B = 317B's small flow high-frequency version, with the same return oil/sealing, smaller flow, and higher frequency response, suitable for 25L/min high-frequency high-precision systems.

Four. Application scenarios

NG6 small installation surface, 25L/min small flow + 350bar (P/A/B) + 120–150Hz high frequency response + standard temperature (≤80℃)

T port low-pressure return oil (≤50bar), no need for Y port leakage

High-frequency high-precision control: High-frequency fatigue testing machine, vibration table, precise position control, high-speed response small flow system

Installation space limited, 25L/min flow is sufficient, need high-frequency dynamic, low-pressure return oil high-pressure system