The AirTAC Airtac 4V Solenoid Valves 4V21008CG-W is a genuine 5/2-way single solenoid (spring return) solenoid valve with W ports and an effective area of 17.0 mm² (Cv 1.0). It is an internally piloted spool valve that directs compressed air to double-acting cylinders and actuators.
The 4V21008CG-W is the externally piloted version of AirTAC's widely used 4V210 single-solenoid valve, built on the 4V200 body with a G1/4 (BSPP parallel) main port and an AC110V coil rated at 4.5 VA. Because the pilot air is fed from a dedicated external port rather than tapped internally from the main line, the spool keeps shifting cleanly even when main-line pressure runs low or sits in a vacuum or low-pressure circuit - a practical advantage on pick-up and venturi-assisted lines where an internally piloted valve would stall. The -W option does not change the flow class: you still get a 17 mm2 effective area (Cv 1.0) and a switch-through time of 0.05 s or less.
Functionally it is a 5/2 spring-return valve for double-acting cylinders and actuators: energise the solenoid and air feeds one cylinder side while the other exhausts; cut the signal and the spring snaps the spool home automatically, so a constant electrical signal is required to hold the far position. At 220 g it bolts onto a manifold base or mounts individually, and the terminal-box entry with the AC110V coil suits 110 V control cabinets.
| Model | Airtac 4V Solenoid Valves 4V21008CG-W |
|---|---|
| Series | 4V200 solenoid valve (spool type) |
| Valve type | 5/2-way |
| Function | Single solenoid (spring return) |
| Port size | W |
| Exhaust port | W |
| Effective area (Cv) | 17.0 mm² (Cv 1.0) |
| Fluid | Air (filtered by 40µm element) |
|---|---|
| Pilot type | Internal / external pilot |
| Operating pressure | 0.15 – 0.8 MPa |
| Proof pressure | 1.2 MPa |
| Max frequency | 5 cycle/sec |
| Response time | ≤ 0.05 s (activating) |
| Temperature | -20 to +70 °C |
| Body material | Aluminum alloy |
| Weight | 220 g |
Specifications follow the official AirTAC 4V series datasheet. Lubrication not required. Confirm coil voltage and thread (PT / NPT / G) against the product label before wiring.
| Effective area | 17.0 mm² |
|---|---|
| Flow coefficient | Cv 1.0 |
| Response time | ≤ 0.05 s |
| Coil power | AC 4.5 VA · DC24V 3.0 W · DC12V 2.5 W |
| Protection / insulation | IP65 (DIN40050), B-class |
| Voltage options | DC24V, DC12V, AC110V, AC220V |
| Manual override | Yes (locking / non-locking) |
Size the valve so effective area / Cv is not the bottleneck for your cylinder bore and speed. Undersized valves slow the actuator. Note 5/3 (center) versions have a smaller effective area than the 5/2 of the same body size.
| 4V | Solenoid valve, spool type, 4-series. |
|---|---|
| 2 | Body size (4V200) — sets port & flow. |
| 1 | Function: 1 = single 5/2, 2 = double 5/2, 3 = 5/3. |
| -W | Port thread: M5 / 06=1/8" / 08=1/4" / 10=3/8" / 15=1/2". |
Related: 4V210 (single), 4V220 (double), 4V230C/E/P (5/3 center). Add the voltage suffix when ordering.
The external pilot keeps the spool switching on vacuum pick-up and low-pressure lines where an internally piloted 4V210 would fail to shift.
Spring-return 5/2 switching with Cv 1.0 drives O32-50 mm clamps, pushers and ejector cylinders in general machine building.
G1/4 BSPP ports and an IP65-rated AC110V terminal coil fit standard 110 V control panels on packaging, indexing and assembly lines.
Pick this SKU when your circuit pressure can drop low enough to starve an internally piloted valve - the external pilot keeps switching reliable in vacuum handling, low-pressure conveying and similar setups. Size-wise, the 4V200 class (17 mm2 / Cv 1.0) suits roughly O32-50 mm bores; drop to the 4V100 (Cv 0.6) for small cylinders, or move to the 4V300 (Cv 1.65) when you need a bigger bore or a faster cycle. A single solenoid (10) with spring return is the right choice when the valve must fail back to one position on signal loss; a double solenoid (20) holds its last position instead, and a 5/3 (30C/E/P) blocks, exhausts or pressurises at center - note those center valves drop to 13.6 mm2 / Cv 0.8 and 3 cycles per second. Use a single valve for one actuator or a base-mounted manifold group for many.
Ordering a replacement: match all five points - 4V200 body, function 10, 1/4" G-thread port, AC110V coil, terminal entry, plus this -W external pilot suffix.
Quick checklist
Instead of tapping pilot air from the main supply inside the valve, this version has a separate external pilot port. That means switching stays dependable even when main-line pressure is low or in vacuum/low-pressure service - the flow class is unchanged at 17 mm2 effective area (Cv 1.0). AirTAC does not publish a minimum pilot-pressure figure for this valve, so size the pilot supply per your application.
It directs compressed air to double-acting cylinders and actuators in the O32-50 mm range (Cv 1.0, response 0.05 s or less). As a single-solenoid 5/2, the valve returns to its normal position by spring the moment the electrical signal is cut - so a constant AC110V signal is needed to keep the cylinder at the extended position. Single-acting cylinders need a 3/2 valve, not this model.
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