Hi-Endurance Switching, Sensing
& Linear Position Sensors

Thermals for Avionic Applications

The safety and redundancy requirements of modern aircraft are one of the many area’s that drive the use of advanced mechanical thermal switches like CPI Thermals. It turns out that while cheap sensors and microcontrollers are a fair solution to many non-critical monintoring apps, the heavy lifting of safe temperature detection is often deffered to one of CPI’s three lines of thermal switches.

The key reasons for this have to do with the robust nature of a thermocouple based solution (particularly CPI’s) and the completely standalone nature of the solution. A local switch closure using our thermals requires no signal interpretation by a complex microprocessor = more things that can go wrong. The extreme reliability of CPI thermal detection around the set point can activate or deactivate systems directly  and provide immediate response to hazardous thermal conditions even when other systems have failed.

CPI Thermal Families Used in Aircraft

CPI offers three lines of thermal switches, covering a detection range from -40F to 1750F depending on the application. These thermals come in a variety of form factors depending on need and if nothing off the shelf suits you there is always CPI custom solutions.

A short overview of our switch families is shown below

Slide 5 Image 1

Bimetallic snap disc technology is reliable in high vibration environments. Single or dual setpoints. 5A resistive, 3A inductive

CPI SnapStat Thermal Switch Family

Compact package, tight specs plus high temperature capability. Bimetallic strip technology with slow make & break contacts

Slide 5 Image 3

Utra-High Temperature Set point capability with quick response. Hysterisis less than 5F. Options for Hermetically sealed designs 

Applications for CPI Thermals

CPI Thermals solve tough problems in temperature detection and mitigation in applications all over the aircraft.


ECS Bleed air O/T

Coolant System O/T

Engine Fire Detection

Engine Anti-Icing Syst

Environmental Control

Oxygen Generation

Starter System

Engine Hydraulics O/T

APU oil O/T

General Fire Detection

Gearbox Oil O/T

Switch Family

Rod & Tube


Rod & Tube





Rod & Tube


Rod & Tube


Switch Model

X1030, X2019




M2 Various



AD059, AD065, AD192



L1007, L1015


Aircraft Type

Learjet L45, P1 Patrol

MD500 Series Chopper


Citation 5

747, 737, DHC7, S-76 



747, Chinook (234)

S-76 Blackhawk

Twin Otter, Various

A109, P109


CPI Thermals Have a Lot of Unhappy Customers

The truth is that a lot of our business comes from engineers who become unhappy with their present source for thermal controls. Whether that’s because they don’t work, don’t work reliably, or they become an unreliable source of supply, they usually end up at our doorstep. The fact that all our parts are “made in the USA” and that we’ve been manufacturing and improving thermal switches for over 75 years, doesn’t hurt either.

For a consult with a knowledgeable expert about your thermal switch application, call our engineering team today at (973) 887-9400

Make The "Switch" to CPI

If your momentary switch application demands high performance, we think you should demand CPI. Please call us today to speak with our engineering team about your needs.

(973) 887-9400