
The AirTAC AirTAC 4A330C-08 Pneumatic Valve, 4A300 Series (4A330C08) is a genuine 5/3-way 5/3 double air pilot — closed centre air pilot valve with PT1/4 ports. It is a sliding-spool valve switched by a compressed-air signal instead of a coil, and it directs air to double-acting cylinders and actuators. The 4A300 body is published at 21.3 mm² effective area (Cv 1.25).
The 4A330C08 is a 5/3-way double air pilot valve in the AirTAC 4A300 series, sized with a 1/4 inch PT (Rc tapered) thread on every port. It directs compressed air to double-acting cylinders and pneumatic actuators, and it is thrown by a pulse of air on one pilot port or the other - there is no coil, no wiring and no electrical rating to worry about. At the centre position the closed-centre design blocks all five ports, so a cylinder parked mid-stroke holds its position until the next pilot signal arrives.
Flow capacity is a 21.3 mm2 effective area (Cv 1.25), the published 5/3 figure for this body, with a no-load switching rate of up to 3 cycles per second and an operating range of 0.15-0.8 MPa. At 505 g it is the heaviest 4A300 valve, and it suits cylinders around Dia 50-80 mm. The PT taper seals on the thread flanks, so wrap the male threads with PTFE tape during fitting. Air reaching the valve must be filtered by a 40 um element.
| Model | AirTAC 4A330C-08 Pneumatic Valve, 4A300 Series (4A330C08) |
|---|---|
| Series | 4A300 air pilot valve (sliding-spool type) |
| Valve type | 5/3-way |
| Function | 5/3 double air pilot — Closed centre |
| Actuation | Double air pilot, spring-centred (exterior air control) |
| Port size | PT1/4 |
| Exhaust port | PT1/4 |
| Thread standard | PT (Rc tapered) |
| Effective area (Cv) | 21.3 mm² (Cv 1.25) |
| Fluid | Air (filtered by 40µm element) |
|---|---|
| Operating pressure | 0.15 – 0.8 MPa (21 – 114 psi) |
| Proof pressure | 1.2 MPa (175 psi) |
| Max frequency | 3 cycle/sec (no load) |
| Temperature | -20 to +70 °C |
| Body material | Aluminum alloy |
| Lubrication | Not required |
| Weight | 505 g |
Specifications follow the official AirTAC 4A series datasheet. AirTAC publishes the effective area / Cv published for 4A330C-10; other port and centre options of this body share the same casting but are not separately rated. Max frequency is the no-load figure. Confirm the thread standard (PT / G / NPT) against the product label before piping.
| Effective area | 21.3 mm² |
|---|---|
| Flow coefficient | Cv 1.25 |
| Control signal | Compressed air (exterior pilot) |
| Pilot ports | Two pilot ports, one per side |
| Electrical parts | None — no coil, no wiring, no IP rating needed |
| Manifold base | 300M (up to 12 stations) |
Because there is nothing electrical in the valve, the 4A suits wash-down, explosive-atmosphere and high-vibration areas where a solenoid would need certification. Size the valve so effective area / Cv is not the bottleneck for your bore and speed; the 5/3 centre versions have a smaller effective area than the 5/2 of the same body.
| 4A | Air pilot valve, sliding-spool, 4-series. |
|---|---|
| 3 | Body size (4A300) — sets port & flow. |
| 30C | Function: 10 = single pilot 5/2, 20 = double pilot 5/2, 30C/E/P = 5/3 closed / exhaust / pressure centre. |
| 08 | Port size: M5 / 06=1/8" / 08=1/4" / 10=3/8" / 15=1/2". |
| (blank) | Thread standard: blank = PT, G = BSPP, T = NPT. This model is PT (Rc tapered). |
Related: 4A310 (single pilot), 4A320 (double pilot, memory), 4A330C/E/P (5/3 centre).
Gate and clamshell cylinders on stone crushers run in abrasive dust that kills coils and connectors. The sealed all-pneumatic 4A330C08 keeps switching, and closed centre parks the gate where the operator last pulsed it.
Clamp arms around a saw line must hold position between cuts. With Cv 1.25 feeding Dia 50-80 mm clamp cylinders, the closed centre blocks A, B, P and exhausts at mid-position so the arms stay clamped without a held signal.
Solvent-laden spray booth air makes electrical switching a certification burden. A remote manual or mechanical signal valve throws this pilot valve with a short air pulse, and the fixture cylinder holds at centre with no electronics in the hazard zone.
Size by flow first: the 4A300 sits mid-range, so step DOWN to the 4A200 (Cv 1.0) for smaller cylinders or step UP to the 4A400 (Cv 2.82) if your Dia 50-80 mm cylinder is running fast or over longer lines. Within the body, pick this 30C closed centre when the load must stay put at mid-position; choose the 30E exhaust centre if the cylinder should float free, or the 30P pressure centre if both sides should be live. If you would rather have spring return with a single signal, the 4A310 and 4A320 5/2 variants are the same envelope.
An air pilot earns its place wherever a solenoid struggles: no coil to burn out, no certification needed in explosive or dusty air, and it tolerates wash-down and vibration on the machine. For replacements, match all four points: body size 4A300, function 30C, port 08, thread PT. One valve works alone; several can share a 300M manifold base with a 3/8 inch common inlet, up to 12 stations.
Quick checklist
It is a 5/3 closed-centre, double air pilot valve with a published effective area of 21.3 mm2 (Cv 1.25), a no-load maximum of 3 cycles per second and an operating pressure range of 0.15-0.8 MPa (21-114 psi). That places it on double-acting cylinders around Dia 50-80 mm; for higher flow step up to the 4A400 (Cv 2.82), for less use the 4A200 (Cv 1.0).
A short air pulse on either pilot port throws the spool; at the centre position all five ports are blocked, so the cylinder ports are sealed and the load stays where it stopped. For suspending or fall-hazard loads, add a pilot-operated check valve or a mechanical brake at the cylinder - never rely on the valve alone as a safety brake. Supply air must pass a 40 um filter, and the PT tapered threads seal on the flanks with PTFE tape.
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