CPI Rod & Tube Thermal Switches – Unique Problem Solvers.

CPI Rod&Tube Thermal Switches

One of the most unique switches in the CPI product catalog, may be our high temperature line of thermal switches, know as “Rod & Tube” thermal switches. With the ability to operate at set points up to 1750F, the CPI Rod & Tube thermal switch stands out. In a world dominated by bimetallic snap-disc thermal switch designs, the rod & tube variety is about as rare as a hot pink unicorn.

And yet for some of the highest temperature applications, ones that require accurate set point switching well over 1000F, there is really no other kind of thermal switch or sensor technology that can take the heat!

When to Consider a Rod & Tube Thermal Switch for Your Application

In fairness, Rod & Tube thermal switches are also considered a bi-metallic thermal switch but the internal architecture of the switch is different allowing for some unique switching characteristics.

Rod & Tube Thermal Switch Diagram

As pictured above, this type of temperature switch operates by utilizing differences in coefficients of expansion of two materials – the rod and the tube.  Since the external tube is the high expanding element, these products (our X, AB, and W Series) offer outstanding response times. They also have the highest set point capability operating from 0F to 1750F (-17.8C to 954.4C).  

Rod and Tube thermal switches and indeed all CPI thermals are designed for high reliability, specifically to be both shock and vibration resistant. The combination of thermal accuracy, fast switching, and high durability make them appropriate for especially challenging military and commercial thermal sensing requirements.

Applications for Rod & Tube Thermal Switches

Critical heat and fire detection applications often rely on our X series Rod & Tube thermal switches owing to their fast switching times and ability to survive in high vibration environments.

X-Series Rod & Tube Thermal Switches
  • Engine Overheat Detection -Pratt & Whitney engines use our X series thermals on certain engine designs to detect engine overheat.
  • Compartment Overheat – Fire detection applications on Gulfstream aircraft for baggage compartment overheat detection.
  • Galley or commercial kitchen fire detection. CPI Rod & Tube thermals are used for critical galley fire detection/prevention systems on Navy ships.
  • Environmental Control system thermal cutoff detection – In commercial aircraft, the ECS (environmental control system) uses our switch to bleed air in case the primary temperature sensors fail. Our X series thermal switches are located after the bleed air valve. If all should fail, the temperature can exceed the 500F rating of the aluminum heat-exchanger further downstream. In this application our switch prevents a shutdown of the cabin HVAC system.
  • Refinery process control – In steel mills, CPI thermals have been used for cauldron temperature monitoring and triggering safety alarm.
  • Plastics Manufacturing – Extrusion machine temperature monitoring. The high temperatures used in plastics manufacturing are monitored using our Rod & Tube thermals (X series)

Other applications for these unique switches include generator over-temp monitoring,  railroad switch flame detection, stack scrubber temperature monitoring, turbine exhaust monitoring, and brake over temp indication on large construction equipment to name a few.

Are CPI Rod & Tube Thermal Switches right for Your Application?

Our rod and tube thermals are typically purchased directly from the factory where we can program the setpoint accurately and insure quality control. All our parts are made right here in the USA in our factory in East Hanover NJ.

For more information, please contact our sales engineers today.