**Oil column height calculation**

To calculate the height of an oil column of specific gravity 0.9 equivalent to a gauge pressure of 20.3 KPa, we can use the equation for pressure in a fluid:

Pressure = ρgh

Where:
- Pressure is the gauge pressure (20.3 KPa)
- ρ is the density of the fluid (oil) in kg/m³
- g is the acceleration due to gravity (9.81 m/s²)
- h is the height of the fluid column in meters

**Density of the oil**

Given that the specific gravity of the oil is 0.9, we can determine the density of the oil using the relationship:

Specific gravity = ρ / ρ_water

Where:
- Specific gravity is 0.9
- ρ is the density of the oil
- ρ_water is the density of water (1000 kg/m³)

Rearranging the equation, we can solve for the density of the oil:

ρ = Specific gravity x ρ_water
= 0.9 x 1000 kg/m³
= 900 kg/m³

**Calculating the height of the oil column**

Now that we have the density of the oil, we can substitute the values into the pressure equation to solve for the height of the oil column:

Pressure = ρgh

Rearranging the equation, we can solve for h:

h = Pressure / (ρg)
= 20.3 KPa / (900 kg/m³ x 9.81 m/s²)
= 20,300 N/m² / (900 kg/m³ x 9.81 m/s²)
≈ 2.21 meters

Therefore, the height of the oil column with a specific gravity of 0.9 equivalent to a gauge pressure of 20.3 KPa is approximately 2.21 meters.

2.3m