I. Model-by-digit Explanation (D633-204)

D633: D633 series direct-acting servo valve (DDV), NG6 (03) mounting surface

204:

2: Flow code → 40 L/min (Δp=35 bar) (The maximum flow rate of D633 series)

0: Electronic / Frequency response → High frequency response (100–120 Hz), analog input, position closed-loop

4: Y port / Seal → No Y port (backflow to T), FKM (fluororubber) seal, -20 to +120℃

In one sentence: D633-204 = NG6 + 40 L/min@35bar + 350bar high pressure + direct actuation without pilot valve + high frequency response + FKM high-temperature seal

II. Core Parameters (Δp=35 bar)

Rated flow: 40 L/min (maximum of D633 series)

Maximum pressure: 350 bar (P/A/B)

Hysteresis: <0.2%

Resolution: <0.1%

Frequency response (±100%): 100–120 Hz (about 40% higher than 183B)

Step response: ≈10–12 ms

Zero position leakage: ≈0.4 L/min (210 bar)

Seal / Temperature: FKM (-20 to +120℃, high temperature resistance)

Drive: 24VDC, ±10V or 4–20mA

Filter: ISO 4406 15/12

Features: No pilot hole, extremely strong anti-pollution, independent of pressure, spring alignment after power loss, high temperature tolerance

III. D633-204 vs D633-183B (Key Differences)

Table

Item D633-204 (40L high frequency) D633-183B (25L standard)

Flow 40 L/min 25 L/min

Frequency response 100–120 Hz 60–90 Hz

Seal FKM (-20 to +120℃) NBR (-20 to +80℃)

Step response 10–12 ms 15 ms

Application positioning High pressure, large flow, high temperature Medium flow, standard frequency response, normal temperature

In one sentence: 204 is the "enhanced version of 183B" with "large flow + high frequency + high temperature", the strongest performance in the NG6 size

IV. Applicable Scenarios

NG6 mounting surface, but with 40L/min large flow + 350bar high pressure

High frequency response (>80Hz), fast response (≈10ms) precise control

High-temperature conditions (oil temperature 80–120℃)

High anti-pollution requirements, no frequent maintenance desired

Precision presses, high-speed injection molding, testing machines, robots, small cylinder diameter high-pressure control in metallurgy