Steam Traps

Thermostatic Steam Traps

Thermostatic Steam Traps, AKA “Rad Traps”, operate using a bellows or capsule element that opens or closes the trap based on the surrounding temperature, relative to the operating pressure. Their simple operation makes for easy use and repair.

Available Steam Traps

Scroll the chart below for an overview of thermostatic steam traps Keystone commonly supplies.

Please contact us for questions, quotations and inquiries. We can also help you find thermostatic  steam traps not listed here.

For chart information on Materials, Capacities, and Dimensions for Barnes & Jones or Edison steam traps, please see below.

Barnes & Jones


Industrial (High-Pressure)

Contact Us

Do you still have questions? Are you looking for pricing information or to place an order?

Do you have questions about thermostatic steam traps?

Thermostatic Steam Traps are balanced pressure devices that use vapor pressure, within a diaphragm or bellows, to open and close within the trap body dependent upon the surrounding temperature. The trap is normally open to expel the ‘cooler’ air and condensate. As the ‘hotter’ saturated steam surrounds the unit, the volatile fill inside the element flashes into a vapor, creating an internal volume induced pressure rise. This increased pressure causes the element to expand to its natural length or “closed position” thus closing the orifice and preventing steam from passing its point of use until the ‘cooler’ condensate once again surrounds the element. The presence of condensate will cool the element and condense the vapor within, reinstating the vacuum, causing the element to retract to its open position and allowing the condensate to drain from the trap.

Thermostatic steam traps are most commonly used in radiators.

They are also used in process applications (especially batch processes) up to 250 pounds pressures.

The main advantages of thermostatic steam traps is that they have a large water handling capacity, as well as a large air handling capacity.

  • All working parts are factory calibrated within the “Cage Unit” ensuring absolute uniformity of performance.
  • 100% Factory tested under live steam and condensate.
  • Heavy Duty Cast Bronze Body.
  • Stainless Steel Valve & Seat.
  • Forged Brass Cover, Union Nut & Tailpiece.
  • Available in angle, straightway, vertical, left hand & right hand piping patterns.

Edison/Barnes & Jones Thermostatic Steam Traps are designed to prevent live steam from passing its point of use, while allowing air and condensate to be expelled from the steam supply into the return line. All Edison/Barnes & Jones Thermostatic Steam Traps are equipped with one-piece, self contained “Cage Units” that are 100% factory calibrated and tested, under live steam and condensate, to ensure uniform operation in the field. The one-piece, self contained design allows for the ease of on-line repair. There are no piping connections that need to be broken, or multiple internal components to be removed. The body of the trap acts merely as a housing for the “Cage Unit” which performs the actual steam trap functions.

Industrial thermostatic steam traps are designed for all types of steam distribution systems, including the following: Tracer lines Sterilizer Platen presses Drying rolls Steam kettles Laundry equipment Textile equipment Petrochemical processing Large mains where air handling is critical Plating tanks High pressure air heating coils Cooking equipment The ability of an industrial steam trap to stop steam at its point of use and expel vast amounts of air and condensate is extremely important to the proper operation of the equipment mentioned above. Working up to pressures of 300 PSIG, an inferior trap can be responsible for incredible waste.

The Barnes & Jones industrial thermostatic trap is rugged enough for the most demanding environment, but also sensitive enough to afford great efficiency for the equipment it is trapping. The unique, solidly encased, one piece thermostatic element, the Cage Unit, is constructed of monel and stainless steel and has been calibrated at the factory under live steam to ensure uniform operation in the field. This element, because of its one piece construction, is fully removable for testing in a test body eliminating the need to ever take the trap off line and dramatically reducing down time of the equipment.

Adoptions of the “Cage Unit” are available to renew all manufacturers’ industrial thermostatic steam traps. Call for “Steam Trap Repair Guide.”

Using a monel bellows, within which is a volatile liquid, sealed under vacuum, the trap opens and closes in a modulating manner dependent upon the temperature affecting it. The trap’s normal state is that of being wide open to expel air and condensate. When surrounded by steam at saturated temperatures, the volatile fill has flashed, creating an internal pressure equal to the surrounding pressure. This equalization of pressures allows the bellows to expand to its natural length or “closed” position, preventing steam from passing. The presence of condensate sufficiently cools the bellows to condense the vapor within, causing the external pressure to be greater and the bellows to revert back to its contracted or “open” position, allowing the condensate to drain from the trap, permitting more steam to enter, thus the modulating action of the trap.