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.
+/- 1 inH2O compound range pressure sensor
DP transmitter with for measuring 300inH2O gas flow across orifice plate
Standby generator 20inH2Og range 0-5Vdc output natural gas and propane pressure sensor
40 inH2O g OEM pressure transmitter with 4-20mA current output
Request info on inh2o - inches of water column unit range pressure measurement products for your application.
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 conversion factors below to convert from inH2O to other pressure units or vice 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.
See how inH2O are derived from SI units or check other forms for describing inH2O.
- Wet wet DP sensor for 10 inches of water range
Genset hydrostatic sensor for measuring level of small diesel tank up to 12 inches- DP transmitter with for measuring 300inH2O gas flow across orifice plate
Minus 0.25 inWG differential pressure transmitter for negative air pressure difference
Request info on inh2o - inches of water column unit range pressure measurement products for your application.
Contents
Conversion Factors
- 0.00249089 bar
- 0.0361273 psi
- 2.49089 mbar
- 249.089 N/m²
- 249.089 Pa
- 2.49089 hPa
- 0.249089 kPa
- 0.000249089 MPa
- 0.00254000 kg/cm²
- 25.4 mmH2O 4°C (39.2°F)
- 2.54 cmH2O 4°C (39.2°F)
- 0.0254 mH2O 4°C (39.2°F)
- 1 inH2O 4°C (39.2°F)
- 0.0833333 ftH2O 4°C (39.2°F)
- 1.86832 mmHg 0°C (32°F)
- 0.186832 cmHg 0°C (32°F)
- 0.0735559 inHg 0°C (32°F)
- 1.86832 Torr
- 1868.32 mTorr
- 0.00245832 atm
- 0.00254000 at
- 2490.89 dyn/cm²
- 0.578037 oz/in²
- 1868.32 µHg 0°C (32°F)
- 0.0000161283 tsi (uk, long)
- 0.0000180636 tsi (usa, short)
- 0.00260117 tsf (usa, short)
- 5.20233 psf
- 2.54 g/cm²
Please note that the conversion factors above are accurate to 6 significant figures.
25 inH2Og range 4-20mA output natural gas pressure sensor for use in generator supply
Seawater solution 60 inH2O hydrostatic pressure sensor for 190degF temperature
20 inWG Liquid compatible pressure transmitter- Wet wet DP sensor for 10 inches of water range
Request info on inh2o - inches of water column unit range pressure measurement products for your application.
Derivation
The calculation below shows how the pressure unit Inches of Water Column (inH2O) is derived from SI Units.
Formula
- Pressure = Force / Area
- Force = Mass x Acceleration
- Mass = Density x Volume
- Volume = Area x Height
- Acceleration = Distance / (Time x Time)
SI Units
- Mass: kilogram (kg)
- Length: metre (m)
- Time: second (s)
- Force: newton (N)
- Pressure: pascal (Pa)
Input Values
- Density = Water Density at 4degC = 1000 kg/m³
- Area = 1 m²
- Height = 1 in = 0.0254 m
- Acceleration = Standard Gravity = 9.80665 m/s²
Calculation
- 1 inH2O Mass = 1000 kg/m³ x 1 m² x 0.0254 m = 25.4 kg
- 1 inH2O Force = 25.4 kg x 9.80665 m/s² = 249.08891 N
- 1 inH2O Pressure = 249.08891 N / 1 m² = 249.08891 Pa
100 inH2Og 4-20mA low concentration acid solution pressure sensor for CIP cleaning- Minus 0.25 inWG differential pressure transmitter for negative air pressure difference
- DP transmitter with for measuring 300inH2O gas flow across orifice plate
- 0.06 inWG positive air pressure transmitter for HVAC blower fan control
Request info on inh2o - inches of water column unit range pressure measurement products for your application.
Alternate Descriptions
These are the different versions used for identifying inH2O that you may find elsewhere.
- Inches of H2O
- Inch of H2O
- Inches of Water Column
- Inch of Water Column
- Inches of Water Gauge
- Inch of Water Gauge
- inH2O
- inWC
- inWG
- inWS
- inAq
- in H2O
- in WC
- in WG
- in WS
- in Aq
- “H2O
- “WC
- “WG
- “WS
- “Aq
Conversion Tables
Select a look up table for converting a pressure reading in inches of water column to other measurement units.
- mmH2O, mbar, psi and mmHg
- bar » 1 to 1000 inH2O → 0.00249089 to 0.00249089 bar
- psi » 1 to 1000 inH2O → 0.00361273 to 3.61273 psi
- Pa » 1 to 1000 inH2O → 249.089 to 249,089 Pa
- kPa » 1 to 1000 inH2O → 0.249089 to 249.089 kPa
5 inH2O g range 4-20mA output air pressure sensor for air cleaning use- DP transmitter with for measuring 300inH2O gas flow across orifice plate
1 inH2O differential intrinsically safe 4-20mA out air pressure sensor for HVAC use- Standby generator 20inH2Og range 0-5Vdc output natural gas and propane pressure sensor
Request info on inh2o - inches of water column unit range pressure measurement products for your application.
Measurement Unit Related Terms
More pages related to measurement unit technical terms.
- at – Technical Atmosphere Pressure Unit
- atm – Standard Atmosphere Pressure Unit
- bar Pressure Unit
- cmH2O – Centimetres of Water Column at 4 deg C Pressure Unit
- cmHg – Centimetres of Mercury at 0 deg C Pressure Unit
- daPa – Dekapascal Pressure Unit
- dyn/cm² – Dyne per Square Centimetre Pressure Unit
- ftH2O – Feet of Water Column at 4 deg C Pressure Unit
- g – Acceleration due to Gravity
- g/cm² – Grams per Square Centimetre Pressure Unit
- hPa – Hectopascal Pressure Unit
- inHg – Inches of Mercury at 0 degrees C Pressure Unit
- kg/cm² – Kilogram per Square Centimetre Pressure Unit
- kg/mm² – Kilogram per Square Millimetre Pressure Unit
- kPa – Kilopascal Pressure Unit
- ksi – Kilopounds per Square Inch Pressure Unit
- mbar – Millibar Pressure Unit
- mH2O – Metres of Water Gauge at 4 deg C Pressure Unit
- mmH2O – Millimetres of Water Column at 4 deg C Pressure Unit
- mmHg – Millimetres of Mercury at 0 deg C Pressure Unit
- MPa – Megapascal Pressure Unit
- mPa – Millipascal Pressure Unit
- mTorr – Millitorr Pressure Unit
- N/cm² – Newton per Square Centimetre Pressure Unit
- N/m2 – Newton per Square Metre Pressure Unit
- N/mm² – Newton per Square Millimetre Pressure Unit
- oz/in² – Ounce per Square Inch Pressure Unit
- Pa – Pascal Pressure Unit
- Pressure
- Pressure Units
- psf – Pounds per Square Foot Pressure Unit
- psi – Pounds per Square Inch Pressure Unit
- Specific Gravity
- Torr Pressure Unit
- tsf – Tons per Square Foot (USA, Short) Pressure Unit
- tsi – Tons per Square Inch (UK, Long) Pressure Unit
- tsi – Tons per Square Inch (USA, Short) Pressure Unit
- Water Density
- µHg – Micron of Mercury at 0 deg C Pressure Unit