I. Model Breakdown (D633-231A)

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

231:

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

3: Electronic / Frequency response → Standard frequency response (60–90 Hz), analog input, position closed-loop

1: Y port / Sealing → With Y port (leakage), NBR (nitrile rubber) sealing, -20 to +80℃

A: Standard type, without special coating, standard voltage version

One sentence: D633-231A = NG6 + 40 L/min@35 bar + 350 bar high pressure + direct actuation without pilot valve + standard frequency response + with Y port + NBR sealing

II. Core Parameters (Δp=35 bar)

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

Maximum pressure: 350 bar (P/A/B); T port (with Y): 350 bar

Hysteresis: <0.2%

Resolution: <0.1%

Frequency response (±100%): 60–90 Hz

Step response: ≈15 ms

Zero leakage: ≈0.4 L/min (210 bar)

Sealing / Temperature: NBR (-20 to +80℃)

Drive: 24VDC (18–32VDC), ±10V or 4–20mA

Filter: ISO 4406 15/12

Features: No pilot hole, extremely strong anti-pollution, independent of pressure, spring alignment in case of power failure, with Y port can withstand high-pressure return oil

III. D633-231A vs D633-204 (Key Differences)

Table

Item D633-231A (40L standard frequency response) D633-204 (40L high frequency high temperature)

Frequency response 60–90 Hz 100–120 Hz

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

Y port With Y port (leakage, T port withstands 350 bar) Without Y port (internal leakage, T port withstands 50 bar)

Positioning Large flow, standard dynamics, high-pressure return oil High flow, high frequency, high temperature, internal leakage

One sentence: 231A is the "standard frequency response + normal temperature + high-pressure Y port" version of 204, suitable for high-pressure return oil applications

IV. Application Scenarios

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

High return oil pressure at T port (>50bar), must have Y port leakage

Standard dynamics (60–90Hz) is sufficient, non-high-temperature environment (≤80℃)

High anti-pollution requirements, no frequent maintenance desired

Precision presses, injection molding, die-casting, testing machines, robots, metallurgical small cylinder diameter high-pressure control