Sensors, Switches, & Bellows

Sensors, switches, and integrated sensing systems are among the most precise components and instruments in any aviation, industrial, or space application. Unison has unparalleled expertise and experience in the design, development, and manufacture of these critical products.

Speed & Temperature Sensors


Whether custom designed to fit a customer's specific needs, or one of our proven off-the-shelf solutions, our line of speed and temperature sensors are perfect for everything from high altitude, high performance aircraft to ground-based turbine and industrial applications.

Unison sensors are made rugged enough to withstand temperature and vibration extremes, stable enough to withstand high overpressure and pressure transients, and sensitive enough to provide accurate controls. Sensor types include temperature-sensitive fluid-filled bellows assemblies, Type K or E thermocouples, Resistance Temperature Detector (RTD), Exhaust Gas Temperature (EGT), Total Air Temperature (TAT), and magnetic speed sensors. From prototype to production, Unison has custom solutions for even the most demanding sensing requirements and budgets.

Typical Speed Sensor Characteristics
Speed Range: 50 to 30,000 RPM
Output Amplitude: 0.5 to 125 volts peak to peak
Pulse Shape: Approximately sinusoidal, symmetrical around zero
Physical Air Gap: .015 to .050 inches
Load Impedance: > 1000 ohms
Operating Temperature: –65°F to 500°F
Connectors: Stud, eyelets, circular

Typical Unison Thermocouple Sensor Characteristics
Temperature: Up to 2300°F
Response Time: 0.25 to 0.50 seconds
Accuracy: Per “special limits of error” material standards
Sheath Material: InconelTM 600, InconelTM X–750, Haynes 188
Typical Unison RTD Characteristics Temperature: –100°C to 500°C
Time Constant: Typically 3 sec at 2ft/sec oil flows
Accuracy: Per IEC 60751 Class B
Housing: 304L, 347, InconelTM 600, InconelTM X–750

Pressure & Limit Switches


Using our extensive experience and specialized production facilities, we have the ability to design and build custom switches that meet the unique specifications of our customers' needs. Our best sellers include our limit, precision, snap-acting, position, fuel flow and pressure switches.

Pressure Switches

Unison pressure switches are designed to perform in the harshest environments on the ground and in the air. Able to withstand temperatures ranging from -320 F to 1050 F and pressures up to 15,000 PSI, our precision- crafted switches are engineered to endure the hostile vibration, shock, pressure, and temperature conditions inherent in today's operating environments. Unison's snap-acting pressure switches offer greater set point stability, vibration resistance, over-pressure capability and cycle life. Our capabilities include absolute, gauge and differential pressure switches as well as differential gauges.

Limit Switches

Unison limit switches are custom designed for the rigors of your application. We offer a variety of actuation and de-actuation mechanisms, including rollers, plungers and buttons. Single-pole and multi-pole, single and double throw designs are also available. We specialize in switches for extremes in temperature, shock and vibration, corrosion and other hostile environmental conditions, as well as switches with longevity requirements.

Limit/Position Switch Performance Characteristics Ranges Electrical Rating: 0.25–2.0 amps at 6 to 28 volts (Logic Level Available)
Temperature Range: –320°F – 1050°F
Terminal Data: MIL–Spec and other connectors, flying leads, solder lugs
Endurance Life: 50,000–100,000 cycles
Case Seal: Open, pressure tight, hermetic, environmental
Construction: Welded, all–metal outer enclosures
Vibration Resistance: 20Gs 10–20,000 hertz
Shock Resistance: 50Gs
Dielectric Strength: 1000 volts max


Unison can design and build custom bellows with smooth contours, uniform wall thickness, and greater strength for any application, in any industry.

Custom Designed Precision Components

From high stress oil-extracting equipment to pressure controls on space missions, Unison bellows are custom engineered to perform under stress, shock, vibration and corrosive agents. Our state-of-the-art manufacturing facilities can accommodate prototype, short runs and long-term volume production. We provide intelligent solutions that include theoretical analysis, design, material selection, manufacturing, testing, field evaluation and service.

Typical Thermal Sensing Bellows Performance Characteristics Temperature: –125°F to 350°F (oil filled goes up to 800°F)
Operating Pressures: 200–300 psia internal, 2–22 psia external, 180–300 psia differential, up to 1050 PSIG Max
Response: Less than 6 seconds in agitated liquid baths for 63.3% total stroke
Vibration: Per MIL–E–8595
Liquid Fill Material: Methanol, butyl alcohol, oil
Life: 150,000 cycles

Tight Tolerances in Tight Spaces

Unison bellows are the perfect solution for applications that require utmost precision. Our manufacturing techniques allow us to maintain tight tolerances on critical dimensions, even holding the outer diameter to within a +/- 0.005" margin.

Omega Design

In addition to our conventional bellows, Unison also specializes in Omega Design Bellows. These bellows feature internal or external flat convolutions, offering extreme flexibility and providing greater control and more equalized stress distribution. This unique and economical design is ideal in tough, high-stress applications where repeatability, reduced hysteresis, constant spring rate, resistance to extreme pressure and longevity are required.