Inch of water
Inches of water is a non-
HVAC
unit.
It is defined as the pressure exerted by a column of water of 1 inch in height at defined conditions. At a temperature of 4 °C (39.2 °F) pure water has its highest density (1000 kg/m3). At that temperature and assuming the standard acceleration of gravity, 1 inAq is approximately 249.082 pascals (0.0361263 psi).[2]
Alternative standard in uncommon usage are 60 °F (15,6 °C), or 68 °F (20 °C), and depends on industry standards rather than on international standards.
Feet of water is an alternative way to specify pressure as height of a water column; it is conventionally equated to 2,989.067 pascals (0.4335275 psi).[3]
In
pounds per square inch (psi, lbf/in2) for larger pressures. One usage is in the measurement of air ("wind") that supplies a pipe organ and is referred simply as inches. It is also used in natural gas
distribution for measuring utilization pressure (U.P., i.e. the residential point of use) which is typically between 6 and 7 inches WC or about 0.25 lbf/in2.
1 inAq ≈ 0.036 lbf/in2, or 27.7 inAq ≈ 1 lbf/in2.
1 inH2O = 249.0889 pascals[3] = 2.490889 mbar or hectopascals = 2.54 cmH2O≈ 0.002458316 atm≈ 1.868320 mmHg≈ 0.0735559 inHg ≈ 0.03612729 lbf/in2
See also
- Pressure head
- Barometer
- Centimetre of water
- Inch of mercury
- Millimetre of mercury
References
- ^ "My pressure gauge is scaled in 'inches' - what does this mean?" http://www.npl.co.uk/science-technology/mass-and-force/faqs/
- ^ "The International System of Units (SI) – Conversion Factors for General Use" (PDF). 2006. p. 12. Archived from the original (PDF) on 2017-10-05. Retrieved 2017-10-05.
- ^ a b Guide for the Use of the International System of Units (SI) (PDF). 2008. p. 50.