♨️ MECH

Free Online Steam Trap Selection Calculator

Select and size a steam trap from condensate load, pressure and application. IS 5290 / ASME basis. Free online mechanical / steam tool, no sign-up.

📐 Standard: IS 5290 / ASME
✅ Free to use
📄 PDF export
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♨️
Steam Trap Selection Calculator
Reference: IS 5290 / ASME
♨️ MECH
Select and size a steam trap from condensate load, pressure and application. IS 5290 / ASME basis. Free online mechanical / steam tool, no sign-up.
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ℹ️ About This Calculator

A steam trap discharges condensate and air from a steam system while holding back live steam. This calculator sizes the trap from the condensate load and the differential pressure, and helps choose the trap type for the application, following IS 5290 / ASME practice.

Traps are sized on the condensate load with a safety factor (2-3× for process, more for start-up), against the differential pressure across the trap. The type matters as much as the size: float & thermostatic for process heat exchangers (continuous, modulating loads), thermodynamic for steam mains and tracing (robust, superheat-tolerant), and balanced-pressure thermostatic for air venting and light loads.

📐 Steam Trap Sizing

IS 5290 / ASME

Trap capacity ≥ condensate load × safety factor

condensate load = process heat / latent heat, kg/h
safety factor = 2-3 (running), higher for start-up
differential ΔP = steam pressure − back pressure
Trap capacity is read at the actual ΔP.

🧮 Worked Example

Example: A heat exchanger condensing 200 kg/h of steam at a 4 bar differential needs a trap rated for at least 200 × 2.5 = 500 kg/h at 4 bar. A float & thermostatic trap suits this modulating process load, discharging condensate continuously as it forms without backing up into the exchanger.

📊 Steam Trap Types & Applications (IS 5290)

Match the trap type to the duty - the wrong type waterlogs equipment or wastes steam:

Trap typeBest forCharacter
Float & thermostatic (FT)Process heat exchangersContinuous, modulating, good air venting
Thermodynamic (TD)Steam mains, tracingRobust, tolerates superheat & freezing
Balanced-pressure thermostaticAir venting, light loadsDischarges cooled condensate, sub-cools
Inverted bucketMains, generalHandles dirt, needs steam priming

Sizing & Best Practice

Apply a safety factor of 2-3 on the running load (more for cold start-up when condensate peaks), size at the actual differential pressure, and check the back pressure in the condensate return. A stalled or undersized trap floods the equipment and kills heat transfer; an oversized or failed-open trap wastes live steam.

Indicative guidance - confirm against IS 5290 and manufacturer capacity charts.

❓ Frequently Asked Questions

How do I size a steam trap? +
Take the condensate load in kg/h, multiply by a safety factor of 2-3 (more for start-up), and select a trap whose capacity at the actual differential pressure meets or exceeds it. A 200 kg/h load at 4 bar needs a trap rated for about 500 kg/h at 4 bar.
What safety factor is used for steam traps? +
Typically 2-3 times the running condensate load, because condensate peaks at cold start-up and loads vary. Heat exchangers and process loads at the higher end; steam mains can use a lower factor since their running load is small.
Which steam trap type should I use? +
Float & thermostatic for process heat exchangers with modulating loads, thermodynamic for steam mains and tracing, balanced-pressure thermostatic for air venting and light loads, and inverted bucket where dirt tolerance matters. Matching the type to the duty is as important as the size.
What is a float and thermostatic steam trap? +
A trap with a float that discharges condensate continuously as it forms, plus a thermostatic element that vents air. It suits modulating process loads like heat exchangers because it drains condensate immediately without backing up and killing heat transfer.
What is differential pressure for a steam trap? +
The pressure across the trap - the steam-side pressure minus the condensate return (back) pressure. Trap capacity is quoted against this differential; a higher back pressure lowers the available differential and the trap's discharge capacity.
What happens if a steam trap is undersized? +
Condensate cannot discharge fast enough and backs up into the equipment, flooding the heat-transfer surface, causing waterlogging, poor performance and water hammer. Sizing with a proper safety factor prevents this.
How do I know if a steam trap has failed? +
A trap failed open blows live steam (visible flash, high loss); failed closed floods the equipment and cools it. Ultrasonic, temperature or sight-glass checks during maintenance surveys detect failures, which waste steam and hurt process performance.
What standard covers steam traps? +
IS 5290 covers steam traps in India, alongside ASME and manufacturer capacity charts. They define the types, testing and capacity ratings used for selection and sizing.

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⚠️ Disclaimer: For preliminary engineering design only. Verify all results with a licensed engineer before use. Full disclaimer →