Steam Theory 1. Basics of Steam What is Steam? Principal Applications for Steam Types of Steam Flash Steam How to Read a Steam Table 2. Steam Heating Heating with Steam Steam Heating Mechanism Overall Heat Transfer Coefficient What is Vacuum Steam? Tracing the Causes of Heat Maintenance Issues 3. Basics of Steam Traps What is a Steam Trap? The History of Steam Traps #1 The History of Steam Traps #2 How Mechanical Traps Work: A Look at their Mechanism and Merits How Disc Traps Work: A Look at their Mechanism and Merits How Bimetal-Type Thermostatic Steam Traps Work: A Look at their Mechanisms and Merits 4. Steam Trap Selection Steam Trap Selection: How Application Affects Selection Steam Trap Selection: Understanding Specifications Steam Trap Selection: Safety Factor and Life Cycle Cost Traps and Orifices Part 1 Traps and Orifices Part 2 Casting vs. Forging Applications of Different Types of Steam Traps Don't Get Steamed : Selecting Steam Trap Design Understanding Steam Traps Compare Two Fixed Orifice Venturi Products to a Variable Orifice Free Float Steam Trap 5. Steam Trap Problems Is My Trap Leaking Live Steam? Temperature Control Trap Precautions Trap Installation Orientation Trap Back Pressure Double Trapping Group Trapping Steam Locking Air Binding My Steam Trap Is Good - Why Doesn't It Work? 6. Steam Trap Management Introduction to Steam Trap Management Steam Trap Losses - what it costs you A Guide to Steam Trap Testing Implement a Sustainable Steam Trap Management Program Impact Plant Performance by Improving the Steam System 7. Water Hammer Water Hammer: What is it? Water Hammer: The Mechanism Water Hammer: Cause and Location Water Hammer: In Steam Distribution Lines Water Hammer: In Equipment Water Hammer: In Condensate Transport Piping Identifying Water Hammer Using a Thermal Camera Mitigation of Water Hammer in Vertical Flashing Condensate Transport Piping Stop Knocking Your Condensate Return Steam Trap Management: Do Something; Anything. Please! 8. Risk Mitigation Steam System Optimization and Risk Mitigation Risk Based Methodology for Industrial Steam Systems Why Bad Things Happen to Good Steam Equipment Beware of the Dangers of Cold Traps Steam System Winterization: How to Protect Your Plant 9. Steam Quality Wet Steam vs. Dry Steam: The Importance of the Steam Dryness Fraction Separators and their Role in the Steam System Clean & Pure Steam Temperature Problems Caused by Air Removing Air from Steam Equipment Air Vents for Steam Steam Quality Considerations 10. Steam Distribution Best Practices for Condensate Removal on Steam Lines Installation Tips for Steam Traps on Steam Mains Erosion in Steam and Condensate Piping Corrosion in Steam and Condensate Piping Allocate New Plant Focus to Steam System Design—Part 1 11. Condensate Recovery Introduction to Condensate Recovery Returning Condensate and When to Use Condensate Pumps Condensate Recovery: Vented vs. Pressurized Systems Condensate Recovery Piping What is Stall? Methods of Preventing Stall Cavitation in Condensate Pumps Steam Heat Exchangers are Underworked and Over-Surfaced Allocate New Plant Focus to Steam System Design—Part 2 Optimize Reboiler Performance via Effective Condensate Drainage Vent Away Condensate Pump Frustrations in a Flash 12. Energy Efficiency Tips to improve steam plant efficiency Advice on Winter Preparation for Steam Systems Insulating Traps Steam Compressors Why Save Energy? Management Strategies for Conserving Energy Recovering Steam Clouds and Waste Heat Waste Heat Recovery Boiler Energy Saving Tips Steam Line Energy Saving Tips Steam-Using Equipment Energy Saving Tips Preventing Steam Leaks Handle Steam More Intelligently Optimize the Entire Steam System Use Available Data to Lower System Cost 13. Compressed Air / Gas Removing Condensate from Compressed Air Preventing Clogging of Air Traps Air Compressor Energy Saving Tips Improving Compressed Air Quality and Countermeasures Against Leaks 14. Other Valves Types of Manual Valves Bypass Valves Check Valve Installation and Benefits Pressure Reducing Valves for Steam Is My Trap Leaking Live Steam? Contents: Have you ever wondered about the vapor clouds seen at the outlet of steam traps? These wisps of vapor can be either live steam or simply flash steam. This article aims to deepen understanding of the subtle difference between the two. Live Steam vs. Flash Steam Live steam is invisible, and when a trap is leaking the short distance of space between the pipe outlet and visible vapor will tend to be clear and of relatively higher velocity and force. If the vapor seen is lower velocity and appears visible immediately at the pipe outlet, then it is most likely flash steam. A quick check of the trap operation will confirm its condition. Trap Discharging to Atmosphere Condensate discharged to atmosphere will always form a slight amount of vapor due to flash evaporation. Unfortunately, without checking, traps may often be misinterpreted as leaking due to the exiting vapor clouds, when in fact the vapor is just comprised of small, high energy condensate droplets that flashed at the lower outlet steam pressure. What Causes the Vapor Clouds at the Outlet of Steam Traps? Condensate flows through piping at a pressure higher than atmosphere. When condensate is discharged to atmosphere, a portion of it immediately evaporates because of the pressure difference. This phenomenon is know as flash evaporation. Flash Evaporation During Condensate Discharge Condensate discharged out of the orifice of a trap partially evaporates (flash evaporation) due to the pressure difference (illustration). The vapor clouds at the outlet of traps appear when this flash evaporated steam (flash steam) condenses in the air to form tiny water droplets. Because of the pressure difference between the trap inlet and outlet, traps discharging hot condensate will always generate some flash steam. The appearance of flash steam (by velocity and force) differs from live steam because when a trap is leaking live steam, the majority of the fluid exiting the trap is typically high pressure steam, which is invisible. On the other hand, with flash steam, typically only a small percentage by mass of the high pressure condensate flashes into steam due to the exit pressure drop. How Much Vapor Is Too Much? Flash steam vapor can appear to be a larger amount than it actually is because the difference in specific volume of flash steam compared to condensate may be over 1,500 times greater. Condensate formed at higher pressure has a corresponding higher temperature, which creates a higher % of Flash and results in greater amounts of visible vapor. Example: If a trap releases 10 kg/h of condensate at 10 barG to atmosphere, the amount of flash steam generated is about 1.6 kg/h. This has a volume of roughly 2.7 m3 (greater than the capacity of 2 large bathtubs). As the flash steam diffuses, it turns into a vapor cloud, which can appear to be large in volume. It's important to remember that this is not steam leakage, but condensate that has flash evaporated. Visual Example of Properly Discharging Trap Discharge from Free Float® traps on a Steam Main In short, good condition traps can operate normally but still appear to be leaking steam because the vapor cloud often seen at the outlet of a trap is caused by the flash evaporation of condensate (flash steam). As the condensate discharge rate fluctuates, the amount of flash steam produced will also vary. When unsure whether a trap is leaking or not, a quick check of the trap condition is recommended. Additional Note As a note of caution, some traps (such as the bimetal-type) may be designed to have a significant amount of sub-cooling of the condensate before discharge. Significant sub-cooling can reduce the amount of visible flash steam, but sub-cooling can result in extremely long condensate back-up at the trap inlet. For applications such as steam main drip or high temperature tracing, such sub-cooling traps are not recommended. Although sub-cooling traps may exhibit less flash steam than traps with little or no sub-cooling, only non-sub-cooling traps are typically recommended for drip or high temperature tracer service to maintain safety and reliable operation. For more information on flash steam, please refer to the article: Flash Steam. Compare Two Fixed Orifice Venturi Products to a Variable Orifice Free Float Steam Trap Temperature Control Trap Precautions Also on TLV.com Free Float® Steam Traps for Process Use Free Float® Steam Traps for Steam Mains and Tracer Lines Steam and Condensate Training Seminars Engineering Calculator