Airtac M5B Basic Type Mechanical Valve M5B21008G
Mechanically actuated · no coil, no pilot airThe AirTAC Airtac M5B Basic Type Mechanical Valve M5B21008G is a genuine 5/2-way basic (plunger) type control valve. A plain plunger head. Pushed by a machine part, a jig or a fingertip. It is an external control, direct-acting valve - the spool is moved mechanically, so there is nothing to wire and no pilot line to plumb. Ports are PT1/4 with a 12.0 mm2 (Cv 0.67) effective area.
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Specifications
| Model | M5B21008G |
|---|---|
| Valve type | 5/2 way, external control, direct acting |
| Actuation | Basic (plunger) type |
| Reset | Automatic (spring) restoration |
| Body series | 200 Series, single control |
| Port size | PT1/4 |
| Effective area | 12.0 mm2 (Cv 0.67) |
| Button colour | Green |
| Fluid | Air, filtered by a 40 um element |
|---|---|
| Pressure range | 0 - 1.0 MPa (0 - 145 psi) |
| Proof pressure | 1.5 MPa (215 psi) |
| Temperature | -20 to +70 C |
| Body material | Aluminium alloy |
| Lubrication | Not required |
| Thread standard | G (BSPP parallel) |
| Spool stroke | 2.0-3.3 mm |
Sliding-column (spool) construction, so operating force is not affected by working pressure - there is no back-pressure effect. Lubrication is not required, but once the valve has been run on lubricated air it must stay on lubricated air; AirTAC suggests ISO VG32 or equivalent. The control set is engineering plastic and must be operated by hand only - never switch it by striking it with a tool. The exhaust outlet sits on top of the body, so a silencer fits directly.
About the M5B21008G
The M5B21008G is a 5/2 way external control, direct acting valve that is thrown purely by hand or by machine contact - there is no solenoid coil and no pilot port anywhere on it. A plain plunger sits on top of the body: a jig, a moving clamp arm or a fingertip presses it, the spool shifts, and a spring snaps the valve back the moment the plunger is released. The green button on this 200 series body makes it easy to spot at a glance on a multi-valve panel. Flow is the largest in the M5 range: a 12.0 mm2 orifice (Cv 0.67) through 1/4in PT ports.
Because the spool is a sliding-column design, the force needed to change over does not rise with working pressure - there is no back-pressure effect, so the plunger feels the same at low pressure as at the full 1.0 MPa. The exhaust outlet sits on top of the body, so a silencer screws straight in without a bracket or elbow. The control set is engineering plastic, which is specified for manual pressing only: press it with a smooth surface or jig, never strike it with a tool.
Typical applications
Clamp-confirmation on a drilling fixture
Mount the valve so the swinging clamp arm of a jig presses the plunger only when the workpiece is fully down. Its output then feeds the drill-cycle start circuit, so the cycle cannot begin on a part that is not clamped. The spring return kills the signal the instant the arm lifts.
End-of-stroke signal on a cut-to-length feed
On a pneumatic feed cylinder pushing stock through a saw or press, a fixed stop plate depresses the plunger at full extension. The 12.0 mm2 orifice keeps a 1/4in signal line to the main valve charged quickly, and the spring return readies the valve for the next stroke.
Manual purge on a spray-booth air line
In a booth where electrical switches are undesirable, an operator presses the green-buttoned plunger to route supply air to a purge cylinder and lets go to exhaust it. No wiring, no coil, and the spring return leaves the line safe if the operator walks away mid-press.
How to choose
If the valve must be hit without aiming, step up from this basic plunger to the M5PM mushroom head; if the plunger would suit a direct push but the trip point is reached by a passing carriage, choose the M5R roller instead, which trips from the side. If the state must HOLD after release - a clamped jig that must stay pressurised while both hands are free - leave the spring-return family and look at the M5Y lever or M5PL latching button. On sizing, this 210 body with a 1/4in port moves 12.0 mm2 (Cv 0.67); the same body on a 1/8in port drops to 9.0 mm2 (Cv 0.50) and the 100 series body to 8.0 mm2 (Cv 0.45), so match the Cv to the cylinder bore before fixing the body size. Respect the published reversal stroke: the spool travel on M5B is only 2.0-3.3 mm. Over-stroking the plunger is an installation error and AirTAC states explicitly that it damages the valve - fit a mechanical stop rather than relying on the operator's feel.
Frequently asked questions
It is a 5/2 way external control, direct acting, mechanically actuated valve with a basic plunger and green button on the 200 series body. Working pressure range is 0-1.0 MPa (0-145 psi), proof pressure 1.5 MPa (215 psi), and working temperature -20 to +70 C with filtered air through a 40 um element. Ports are PT1/4, the effective orifice area is 12.0 mm2 (Cv 0.67), and the body is aluminium alloy. Lubrication is not required, though if lubricated air is used it should be kept consistent - AirTAC suggests ISO VG32.
The published spool (reversal) stroke for M5B is 2.0-3.3 mm, and as a plunger type it has no separate actuator over-travel built in. Exceeding the reversal limit damages the valve - AirTAC warns of this explicitly - so the trip face must meet the plunger against a fixed stop that bottoms out within the limit. If your mechanism cannot guarantee a controlled stop, a roller actuator such as the M5R, which has its own 4.6-6.8 mm actuator travel, is the safer choice.