What is the ratio of suction pressure to discharge pressure in a centrifugal compressor operating at 3 psig and 10 psi respectively?

To determine the ratio of suction pressure to discharge pressure in a centrifugal compressor, you would first need to convert the provided pressure values from psig to absolute pressure (psia).

Pressure in psia is calculated by adding atmospheric pressure (approximately 14.7 psi at sea level) to the gauge pressure (psig).

For the given values:

• Suction pressure: 3 psig + 14.7 psi = 17.7 psia

• Discharge pressure: 10 psig + 14.7 psi = 24.7 psia

Next, the ratio of suction pressure to discharge pressure is calculated as follows:

Ratio = Suction Pressure (psia) / Discharge Pressure (psia)

Ratio = 17.7 psia / 24.7 psia

Carrying out this division gives you approximately 0.715. Since the choices provided are greater than 1, we may need to recheck which ratio is being asked.

If instead, one needs the inverse of this ratio (representing discharge pressure over suction pressure, which is common in compressor discussions), the calculation would proceed as follows:

Ratio = Discharge Pressure (psia) / Suction Pressure (psia