Speed Probe Airpax – High-Precision Non-Contact Rotational Speed Sensor

The Speed Probe Airpax is a high-precision sensing device used for detecting rotational speed in demanding industrial applications. Engineered for accuracy and reliability, this speed probe is ideal for environments where performance and consistency are critical.

With its non-contact magnetic sensing technology, the Speed Probe Airpax delivers real-time feedback on rotating equipment such as motors, generators, turbines, and compressors. Its rugged construction allows it to operate in harsh conditions, including high vibration and temperature extremes, ensuring dependable performance over long operational lifetimes.

Airpax speed probes are well-known in the industry for their robust mechanical design and electromagnetic compatibility. The probe is typically installed near a rotating gear or shaft, detecting gear teeth or slots as they pass by. It converts this motion into a frequency signal that is proportional to the rotational speed, enabling accurate control and monitoring by PLCs, controllers, or instrumentation systems.

The Speed Probe Airpax supports wide voltage ranges and output types (such as digital or frequency), allowing flexible integration into various systems. It is resistant to oil, dust, and other industrial contaminants, ensuring long-term operation with minimal maintenance.

Key applications include engine speed sensing, shaft rotation monitoring, overspeed protection, and machine synchronization. Its high signal integrity and low susceptibility to noise make it an excellent choice in high-performance automation and control systems. Whether in power generation, marine, railways, or aerospace sectors, the Speed Probe Airpax helps protect assets and optimize operations.

This speed probe meets international standards and is tested for accuracy, response time, and environmental resilience. Installation is simple, and most models are available with threaded or flange-mounted designs to suit your specific application.

Correct probe selection and installation air gap are what determine long-term signal reliability in the field. For industries seeking reliability, precision, and durability, the Speed Probe Airpax is a trusted solution. Its proven design and high signal fidelity make it essential for any setup requiring precise speed monitoring.

Technical Specifications

Airpax/AI-Tek speed probes of this class use variable-reluctance magnetic pickup technology: as ferrous gear teeth or a toothed target wheel pass the sensor’s pole piece, the changing magnetic field induces an AC voltage in the internal coil, producing a frequency output directly proportional to rotational speed — with no external power required to generate the signal.

Why Passive Sensing Matters

Because the variable-reluctance design generates its own signal from the target’s motion rather than requiring an external excitation supply, these probes are inherently simple and rugged, with no active electronics at the sensing tip to fail from heat, vibration, or contamination — a significant advantage in high-temperature gearbox and turbine casing locations where an active (powered) sensor’s electronics would be the more likely failure point. The tradeoff is that output amplitude varies with target speed and air gap, so the receiving instrument (tachometer, speed switch, or governor) must be matched to the probe’s expected voltage range at the application’s minimum operating speed.

Application Notes: Overspeed Protection and Synchronization

In overspeed protection service, two or more speed probes are often installed redundantly on the same shaft, each feeding an independent trip channel, so that a single probe or wiring fault cannot mask a genuine overspeed condition — a common architecture on turbines, compressors, and generators governed by API 670 or similar machinery protection standards. In synchronization applications, the probe’s frequency output is compared against the grid or reference frequency to time breaker closure, where the sensor’s frequency response and signal integrity at the specific target speed directly affect synchronization accuracy.

Because the mounting air gap between the probe tip and the target wheel affects output amplitude, correct installation per the manufacturer’s gap specification is essential: too large a gap can drop the signal below the receiving instrument’s trigger threshold, particularly at low speeds where output amplitude is already reduced.

Industries Served

Seven Star LLC supports refineries, gas processing plants, marine vessels, and power generation facilities across Oman and the GCC with genuine Airpax and AI-Tek speed sensing hardware for critical rotating equipment, including replacement probes matched to an existing installation’s mounting thread and electrical characteristics so a spare part swap does not require re-engineering the monitoring loop.

Selection Checklist

A mismatched output range is one of the most common field issues with passive speed sensors: an instrument set to trigger on a 40 V signal will not reliably detect a probe delivering only 5-10 V at low target speed, so always cross-check the receiving tachometer or governor’s input sensitivity against the probe’s rated output at the slowest speed the system must detect.

Before ordering a replacement probe, confirm the mounting thread size, the required frequency/output voltage range at your equipment’s minimum and maximum operating speed, the target wheel’s number of teeth, the mounting air gap specified for your installation, and the ambient temperature at the sensor location — a gearbox-mounted probe on a hot compressor casing may need the high-temperature variant rated to +232°C rather than the standard -55°C to +107°C range.

Why Seven Star LLC

Seven Star LLC supplies genuine Airpax/AI-Tek passive speed sensors to industrial customers across Oman and the wider GCC, verifying the exact mounting thread, frequency range, and output voltage class against your existing tachometer, overspeed trip, or governor system before dispatch.

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