Hiscox’s Heintz steam trap uses a semicircular element made from two metals: their different thermal expansion moves a valve. The calculator below is a separate assumed flow-scaling exercise. Its bucket illustration does not depict this historical temperature-responsive mechanism, and its values are not Heintz capacity ratings.
Heintz Steam Trap Interactive Calculator
Explore diameter-squared and square-root-pressure scaling from an explicitly stated reference case: 600 lb/h at 5/16 in and 80 psi. This is not a trap rating or selection calculator.
Equation Used
- The assumed reference case is exactly 600 lb/h at 0.3125 in and 80 psi differential.
- Flow scales with area and the square root of differential pressure for this comparison only.
- The bucket illustration is separate from the historical Heintz thermal mechanism.
- No discharge coefficient, fluid state, density, subcooling, flash steam, backpressure, venting, startup load, dirt, wear, installation, materials, pressure rating or safety model.
Reference-scaling arithmetic only. The 600 lb/h normalization is an assumption, not a Heintz rating. These results do not size a trap or establish pressure-equipment operating conditions.
A temperature-responsive valve
Entry 413 in Hiscox’s Mechanical Movements, Powers, Devices and Appliances describes two metals in a semicircular arc. Their unequal expansion opens or closes the valve. This is a thermal operating principle, distinct from buoyancy acting on a bucket.
The illustration below the controls is a generic bucket-and-valve sketch with a preset seven-second cycle. It does not represent the Heintz thermal element, and none of the calculation inputs determines the bucket’s motion.
Steam-trap function
Steam traps discharge condensate from steam systems using mechanisms responsive to temperature, density or fluid behavior. Different operating principles require different selection information.
For an actual trap, use its identifiable manufacturer capacity data, pressure-temperature limits and installation requirements. The hypothetical reference in this calculator cannot supply those product details.
The assumed scaling rule
dcomparison = 0.3125√[(L/600)/√(ΔP/80)]
difference = 100(C/L − 1)
F = ΔPπd²/4
Diameter d is in inches, differential pressure ΔP in psi, and comparison load L in lb/h. The hypothetical reference is 600 lb/h at 0.3125 inch and 80 psi. It is an assumed normalization, not measured Heintz performance.
The comparison diameter is the algebraic solution that makes C equal L under that same rule. Scenario difference compares C with L as a percentage; it is not a capacity margin. F is pressure difference times a circular projected area in square inches, giving lbf. It does not include a valve stem, spring, thermal element or leverage.
The tool includes no fluid density, discharge coefficient, temperature, phase-change behavior or thermal-valve motion. Consequently neither its flow comparison nor its diameter result can select a steam trap or replacement seat.
A numerical comparison
With d = 0.3125 inch, ΔP = 80 psi and L = 600 lb/h, C is 600 lb/h by definition, comparison diameter is 0.3125 inch and scenario difference is zero. The ideal projected-area force is 80π(0.3125)²/4 ≈ 6.14 lbf.
At the same diameter and 20 psi differential, the assumed scaled value is 300 lb/h because √(20/80) = 0.5. Against the same 600 lb/h comparison load, the reported difference is −50%. These ratios demonstrate the equation, not actual trap behavior.
Limits of the comparison
Actual condensate discharge depends on the trap, fluid conditions and rating basis. Temperature, backpressure, air handling and startup load can matter. This arithmetic does not establish the pressure rating, material condition, operating setting or suitability of any historical or current trap.
Frequently asked questions
Is the displayed flow a rated capacity?
No. It is calculated from an assumed 600 lb/h reference at 0.3125 inch and 80 psi differential.
What does comparison diameter mean?
It is the diameter that makes the assumed scaling equation equal the entered comparison load. It is not a seat dimension or modification recommendation.
Does the bucket animation depict the Heintz trap?
No. Hiscox describes a two-metal semicircular thermal element. The bucket drawing is a separate generic sketch.
Do inputs control the illustrated valve cycle?
No. The illustration has a fixed seven-second cycle and does not calculate bucket buoyancy or thermal-valve response.
What does ideal pressure force calculate?
Only differential pressure times the projected circular area. It is not an operating force for the complete valve mechanism.
References and calculation basis
- Gardner D. Hiscox, Mechanical Movements, Powers, Devices and Appliances, entry 413: the Heintz thermal element.
- Spirax Sarco: steam-trap operating principles.
The 600 lb/h normalization is a hypothetical calculation assumption. It is not sourced to a product capacity table.
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