2S Series Pilot-Operated Normally Closed

More Than a "Switch": The AirTAC 2S Pilot Series — A Stainless Steel Beast

In industrial automation, engineers face a polarizing dilemma: the need for massive fluid flow rates coupled with the reality of harsh or corrosive media. Traditional brass valves often suffer from a short service life when exposed to deionized water, cleaning agents, or fuels. Conversely, using a "direct-acting" valve for high-volume flow requires a solenoid so large it becomes an electrical liability.

The AirTAC 2S-Pilot (Normally Closed) Series is the definitive response to this challenge. It is a precision-engineered solution built specifically for the "High-Flow, High-Corrosion" matrix. By utilizing fluid physics to amplify a low-power control signal, the 2S series delivers uncompromised reliability in the factory's most demanding zones.

Pilot-Operated Leverage: Uses a low-power 6.5W coil to "un-cork" massive orifices, achieving flow rates (up to 49.0 Cv) impossible for direct-acting coils.
Zero-Contamination Materials: Standardized with a SUS304 Stainless Steel body and FPM-F (Viton) seals for total resilience against weak acids, oils, and high-purity water.
MOPD Efficiency: Optimized for pressure-assisted systems, requiring a Minimum Operating Pressure Differential of 0.05 MPa (7.3 psi).
Massive Scalability: A seamless family of valves scaling from 1/2" to a full-bore 2" main-line header.
IP65 Field Readiness: Choice of modular DIN (CDA) or flying lead (CLA) connections for varied OEM and maintenance environments.

1. The Leverage Strategy: Internally Piloted NC

The 2S Series uses the system's own fluid pressure as the "muscle." This "lever" strategy allows a small, efficient coil to manage heavy-duty loads:

How it Works

Power OFF: Inlet pressure travels through a tiny pilot channel to a chamber above the diaphragm. Since the top area is larger than the main orifice, the valve seals itself tighter as system pressure increases.

Power ON: The coil opens a tiny release valve. This "dumps" the pressure above the diaphragm. The massive inlet pressure from below then easily lifts the entire main seal, allowing a tsunami of flow with minimal electrical effort.

2. Engineering Decision: The 0.05 MPa Threshold

The 2S Series relies on Minimum Operating Pressure Differential (MOPD). This is the "fuel" for the pilot engine. If the difference between your inlet (P1) and outlet (P2) is below 0.05 MPa (7.3 psi), the valve will click, but the main seal will remain shut.

⚠️ DESIGNER'S RULE: Use the 2S-Pilot Series for pump-driven circuits, city water supplies, and main air lines. DO NOT USE for gravity-draining, vacuum, or closed-loop systems where pressure equalizes. For those tasks, specify the AirTAC 2KS Direct-Acting series.

3. The Material "Fortress": SUS304 + FPM-F

AirTAC has made a "no-compromise" choice for the 2S Series chemical interface:

SUS304 Structural Defense

Provides superior resistance to deionized water (which leaches zinc from brass) and provides FDA-compliant purity for food and pharmaceutical applications.

FPM-F (Viton) Standard

Unlike NBR or EPDM, FPM-F is the "universal survivor." It maintains seal integrity when exposed to petroleum oils, fuels, and mineral acids up to 150°C.

4. The Flow Ladder: Volumetric Mastery

The 2S Series is defined by its Cv (Flow Coefficient). Sizing should be performed based on required throughput, not just line size:

2S150 (G1/2")

Cv = 5.50
Standard for machine tool coolant inlets and medium process lines.

2S250 (G1")

Cv = 12.50
The workhorse for facility air drops and rapid tank filling.

2S500 (G2")

Cv = 49.00
The flagship "Behemoth." Engineered for facility-wide shutoffs and large-scale reactor dumping.

Technical FAQ

"Can I use the 2S for Acetone or Ketones?"

NO. While Viton (FPM) is a powerhouse against oils, it is severely degraded by ketones and esters. For those specific solvents, you must consult our team for a PTFE-sealed variant.

"How do I choose between DIN (CDA) and Flying Leads (CLA)?"

For end-users, DIN (CDA) is the superior investment; it allows a 1-minute coil swap during maintenance. Flying Leads (CLA) are cheaper for high-volume OEMs but require a licensed electrician for every coil replacement.

Uncompromised Fluid Integrity

In the world of fluid control, there is no "best" valve, only the "right" valve. The AirTAC 2S Pilot Series has a clear identity: it is the specialized problem-solver for high-flow, corrosive, or high-purity applications. By combining the pilot principle for energy efficiency with a SUS304 + Viton armor set, it provides the robust performance that modern Industry 4.0 demands.