Convert Technical Atmospheres to Inches of Water
Convert Technical Atmospheres (at) to Inches of Water (inH₂O) instantly and accurately.
Conversion Formula
inH₂O = at × 393.7007874
About Technical Atmospheres
One technical atmosphere (at) = exactly 1 kgf/cm² = 98,066.5 Pa ≈ 0.968 standard atmospheres. The metric technical pressure unit used in pre-SI European and Japanese engineering for boilers, hydraulic cylinders, and compressed gas systems. A steam boiler at 10 at operates at 0.981 MPa; hydraulic presses are rated at 200-600 at. Still used parenthetically in old German and Japanese machinery manuals and standards (DIN 1301-3 legacy). Converts simply from kgf/cm²: 1 at ≡ 1 kgf/cm². 1 at = 98,066.5 Pa.
About Inches of Water
One inch of water column (inH₂O or in WC) = pressure from 1 inch of fresh water at standard gravity ≈ 249.09 Pa. The standard unit for low-pressure measurement in US HVAC and plumbing: ductwork static pressure, fan performance, filter ratings, and gas appliance manifold pressures are all specified in inches WC. Household natural gas supply pressure is typically 7 in WC (0.25 psi). Blower door tests for building air-tightness use 50 Pa ≈ 0.2 in WC test pressure. 1 inH₂O = 249.089 Pa.
Quick Reference Table
| Technical Atmospheres (at) | Inches of Water (inH₂O) |
|---|---|
| 1 at | 393.701 inH₂O |
| 2 at | 787.402 inH₂O |
| 5 at | 1968.5 inH₂O |
| 10 at | 3937.01 inH₂O |
| 25 at | 9842.52 inH₂O |
| 50 at | 19685 inH₂O |
| 100 at | 39370.1 inH₂O |