Can Venturi Steam Traps Fail? A Comparison of Steam Trap Failure Mechanisms.

All mechanical steam traps fail in only two ways … failed open and failed closed. Let’s walk through each one of these and compare the failure mechanisms of Venturi steam traps to mechanical type steam traps.

FAILED OPEN

MECHANICAL STEAM TRAP: This means that the mechanism that prevents steam from getting past the trap has “stuck open” and it is allowing steam to just blow through the trap. For example, a float and thermostatic trap has a float ball that actuates the valve that closes the downstream opening. When the attachment mechanism breaks. or the float loses buoyancy, the opening cannot be closed and steam will escape. Having live steam in the condensate system is not a good situation since now the pressure of the condensate system is at the same pressure as the steam system. This higher pressure and live steam can cause other steam traps to stop working and it will cause the condensate return system to fail in multiple places. And with live steam leaking past the trap, steam wastage in the system will increase and cause the steam boilers to run more often with longer cycles, which increases fuel costs, raw water costs, and water treatment costs.

SMART VENTURI STEAM TRAP: Since these traps have no internal mechanical parts at all, the Venturi steam trap cannot fail open.

FAILED CLOSED

MECHANICAL STEAM TRAP: This means that the mechanism that is supposed to hold the steam back has failed to operate and is in the “stuck closed” position. In this situation, condensate will form and will not be discharged from the trap. Condensate will continuously back up, eventually filling the heat exchanger and application inlet with warm condensate. In a heating application such as a radiator or a unit heater, this means that the heater will not produce the amount of heat that it is designed to produce. In a process application, this will result in a failure to heat the material properly, causing serious process yield or quality issues. From a safety standpoint, the meeting of cold condensate and hot steam will produce “water hammer”. In severe cases, the water hammer effect can cause valves and other system piping components to catastrophically rupture, spraying hot steam and warm condensate in the area of the failure.

SMART VENTURI STEAM TRAP: Since SMART Venturi traps have no mechanical parts, they cannot fail closed in the traditional sense. However, if the channel opening at the mouth of the Venturi becomes clogged with debris from the steam system piping, condensate can begin to back up and the results would be the same as explained above. To help prevent this situation from occurring, SMART Venturi traps have two built-in strainers to prevent the channel opening from being clogged. These strainers are easily accessible for cleaning and maintenance. For the best operation of a system with Venturi traps, it is imperative that the steam system and the steam/condensate be free of products of corrosion. Also, a good water treatment program needs to be in place in addition to a good preventative maintenance program for Y-strainers and Mud Legs throughout the steam system.