Solenoid Valve Voltage Selection Guide: Electrical Specifications and Airtac Standards

July 5, 2026

In pneumatic automation design, selecting the correct voltage profile for solenoid valve coils is a foundational decision that directly links the mechanical pneumatic system with the electronic control network (such as a PLC or industrial PC). The solenoid coil is an inductive load responsible for converting electrical energy into the linear magnetic force required to shift the valve spool.

Sizing or specifying the incorrect voltage code introduces systemic errors: over-voltage accelerates thermal breakdown and burnouts, while under-voltage causes dynamic switching failures and system stalls. This technical guide outlines the engineering principles of voltage selection, distinguishes between AC and DC power dynamics, and cross-references standard electrical options within the Airtac product architecture.

1. AC vs. DC Voltage: Core Electrical Principles

Solenoid valve coils are wound with copper magnet wire and are engineered to operate under either Alternating Current (AC) or Direct Current (DC). The underlying electrical behavior changes fundamentally between these two source types.

A. Direct Current (DC) Coil Characteristics

Direct Current flows uniformly in a single direction.

Impedance Profile: The electrical current flowing through a DC coil is governed purely by the steady-state electrical resistance ( $R$ ) of the copper wire, according to Ohm’s Law ( $I = V/R$ ).
Inrush Currents: DC coils maintain a consistent, uniform current draw from the millisecond they are energized until they are powered down. There is no large surge current upon activation.
Holding Stability: DC systems are widely chosen for modern electronic automation because they emit minimal electromagnetic interference (EMI) and do not produce the audible hum or chatter sometimes associated with AC magnetic fields.

B. Alternating Current (AC) Coil Characteristics

Alternating Current periodically reverses direction, standardly cycling at a frequency of 50 Hz or 60 Hz.

Impedance Profile: The total opposition to current in an AC coil is defined as Impedance ( $Z$ ), which combines both the standard DC resistance ( $R$ ) and the Inductive Reactance ( $X_L$ ). Inductive reactance depends strictly on the physical positioning of the internal iron plunger.
The Inrush Current Phenomenon: When an AC coil is first energized, the internal iron plunger is in its unseated position, meaning the magnetic circuit is open and the coil inductance is at its lowest baseline. This causes a massive spike known as Inrush Current, which can be 3 to 5 times higher than the continuous Holding Current.
Risk of Burnout: If mechanical debris or an internal component binding issue physically prevents the plunger from sealing completely when energized, the coil remains stuck in the high-inrush phase. This rapidly overheats the copper windings, leading to insulation failure and coil burnout.

2. Standard Voltage Options and Airtac Suffix Nomenclature

Airtac designs and labels its directional control solenoid valves (such as the standard 4V series, 3V series, and 2W series) with standardized classification codes to identify the required coil electrical configuration.

When configuring an Airtac part number string, the primary operating voltage is designated by a specific standard suffix letter positioned at the end of the ordering block:

Voltage Suffix Code	Nominal Voltage	Power Type	Electrical Frequency
A	AC220V	Alternating Current	50 Hz / 60 Hz
B	DC24V	Direct Current	N/A (Steady State)
C	AC110V	Alternating Current	50 Hz / 60 Hz
E	AC24V	Alternating Current	50 Hz / 60 Hz
F	DC12V	Direct Current	N/A (Steady State)

Industrial Application Context for Common Voltages

DC24V (Suffix B): This is the dominant standard across modern industrial automation, automotive lines, and PLC control panels. It provides high safety margins for human interaction and interfaces directly with transistorized solid-state outputs without requiring auxiliary mechanical relays.
AC220V (Suffix A): Frequently utilized in facility infrastructure systems, water treatment plants, or standalone machinery installations where direct heavy mains power is accessible without configuring a dedicated DC switching power supply unit.

3. Electrical Tolerances and Power Consumption Profiles

Operating a solenoid valve outside its designated electrical parameters causes predictable component degradation. Engineers must design power budgets around verified manufacturer limits.

A. Voltage Tolerance Windows

Airtac technical manuals specify a standardized allowable voltage fluctuation window to ensure reliable armature actuation:

\text{Allowable Fluctuation} = \pm 10\% \text{ of Nominal Rated Voltage}

Under-Voltage Risks: If a DC24V system drops below $21.6\text{ V}$ due to line resistance or inadequate power supply capacity, the magnetic flux generated may fail to overcome the internal return spring force. The valve will stick or display an inconsistent, lagging response time.
Over-Voltage Risks: If an AC220V circuit exceeds $242\text{ V}$ , the excess current accelerates thermal loading within the encapsulation resin, leading to degradation of the wire varnish and eventual structural failure.

B. Power Consumption Specifications (Power Scale)

The required electrical wattage changes depending on the valve body frame size and application class. Standard Airtac industrial coils (such as those configured for the 4V210 series) display the following baseline power draws under continuous-duty operation:

Direct Current (DC24V / DC12V): Standard power consumption typically ranges from $3.0\text{ W}$ to $4.8\text{ W}$ . Low-power high-efficiency variants can drop to approximately $2.0\text{ W}$ to reduce heat build-up in tightly packed manifold arrays.
Alternating Current (AC220V): Standard continuous holding power scales around $3.5\text{ VA}$ to $5.5\text{ VA}$ (Volt-Amperes), with inrush values tracking significantly higher.

4. Electrical Termination Types and Environmental Protection

Airtac valves offer different electrical connection styles that dictate how the coil interfaces with physical wiring networks and handles environmental dust and water ingress.

A. Terminal / DIN Connector Type

This design utilizes a standardized detachable plastic plug housing conforming to international industrial standards (such as ISO 4400 / EN 175301-803 Form B or Form C).

Wiring Method: Screw terminals are housed inside the removable plug, allowing technicians to detach the entire electrical supply line without physically unscrewing the valve from the pneumatic manifold.
Ingress Protection Rating: Typically achieves IP65 compliance when installed with the correct integrated rubber sealing gasket and retention screw, protecting against dust intrusion and direct water jets.

B. Grommet Type

Features fixed, insulated flying wire leads extending directly out from the molded epoxy coil encapsulation.

Wiring Method: Requires hardwired connections inside an external junction box or wire conduit.
Application Context: Selected for compact space limitations or basic machinery setups where modular connector detachment is unnecessary.

5. Engineering Field Selection Checklist

Prior to final submission of a procurement order or automated design draft involving Airtac electronic control elements, execute this verification protocol:

Match Control Output Type: Cross-check the PLC output module specifications. If using an NPN/PNP transistor card, ensure the Suffix B (DC24V) coil option is specified. Do not connect AC coils directly to standard solid-state DC logic outputs.
Calculate Total Power Budget Capacity: Sum the aggregate wattage of all solenoid valves capable of simultaneous execution. Verify that the system's 24V DC switching power supply has sufficient amperage headroom, especially when factoring in inductive line losses across long cable runs.
Verify Insulation Temperature Limits: Standard Airtac coils conform to Class B or Class F insulation standards. Ensure that ambient operating environments do not exceed the standard continuous limit of $50^\circ\text{C}$ to $60^\circ\text{C}$ when the coil is held energized over long production cycles.
Confirm Ingress Protection Requirements: If the valve block is mounted near liquid spray or chemical washdown processes, specify the Terminal Type with a complete DIN connector gasket setup to maintain IP65 environmental protection.

Back to blog