|
Home
> Pressure Measurement Glossary
inH2O - Inches of Water Column at 4 deg C Pressure Unit
Inches of water gauge or column is an english and american unit for measuring liquid level. 1 inch of water column at 4 degrees celsius equals 249.089 Pascals.
The hydrostatic pressure generated by a certain liquid level is typically represented by the equivalent height of a water column. Since the pressure exerted by one inch of water is dependent on its density and the local gravity it is not a fundamental unit of measure for pressure but a derived one which is called a manometric unit.
Inches of water column or water gauge are used throughout the world for measuring shallow liquid level and low pressures such as differential air pressures in ventilation systems.
Since the density of a liquid is affected by changes in temperature, inches of water column should be accompanied by the temperature of the liquid that the units were derived. A pure water density of 1000 kg/m3 at 4 deg C and standard gravity of 9.80665 m/s2 is used in the calculation of this pressure unit. The significance of 4 degrees Celsius (39.2 degrees Fahrenheit) is that it is very close to the temperature that water reaches its maximum density.
It is conventional practise to use 1000 kg/m3 as the density of pure water at 4 deg C which is very close to the precise density and for most measurements this does not introduce any significant error. In fact since the temperature can vary significantly, measuring pressure in inches of water is never going to be a precise representation of the true liquid height. Local gravity also varies at different geological locations, which also adds some minor uncertainties to the use of inches of water gauge as an indication of exact water level in different parts of the world.
Use the following conversion factors to convert from inH2O to other pressure units or vica versa. To convert a reading in inH2O to another unit multiply it by the relevant pressure conversion factor. To convert a reading in any pressure unit to inH2O divide it by the relevant pressure conversion factor.
Alternatively convert from inH2O into another unit using the inches of water converter table or the pressure unit converter.
inH2O Pressure Conversion Factors
Please note that the conversion factors above are accurate to 6 significant figures.
Home
> Pressure Measurement Glossary
Request Info | Ask a Question
|
Site Last Updated: 10/09/10
Reference
Glossary - Find explanations for terminology used in specifying and using pressure instruments
Pressure Conversion - Look up conversion factors or select a conversion table for a particular pressure unit
Pressure Measuring Guide - Collection of guidance notes for sourcing, setting up and using pressure measurement equipment
News Articles - Archive of application notes, product releases and technical information
Specify
Pressure Sensor Specification - Select parameters with PSAT to generate a spec for your own use or to submit as an enquiry
Product Finder - Choose multiple product and application types to filter out a suitable product
Contact
|
