SPED Fluid Dynamics & Flow Analysis 3

Question 1

In gas pipeline design, the Weymouth equation is most accurate for:

Accepted Answer

High-pressure, large-diameter, long gas transmission lines

Answer

The Weymouth equation is empirically developed for high-pressure gas transmission pipelines and assumes fully turbulent flow.

Question 2

Choked flow in a gas line occurs when the gas velocity at the restriction reaches:

Accepted Answer

The local speed of sound (Mach 1)

Answer

Choked (critical) flow occurs when gas velocity reaches Mach 1 at the minimum cross-section; further reducing downstream pressure cannot increase mass flow.

Question 3

The equivalent length method for minor losses converts a fitting's resistance into:

Accepted Answer

A length of straight pipe with the same frictional pressure drop

Answer

The equivalent length Le expresses a fitting's pressure loss as the length of straight pipe that would produce identical friction loss, so Le = K·D/f.

Question 4

Flashing in a liquid piping system occurs when:

Accepted Answer

Static pressure drops below the fluid's vapor pressure

Answer

Flashing occurs when local static pressure falls below the saturation (vapor) pressure, causing partial vaporization of the liquid.

Question 5

For a gas flowing through a pipe, the Panhandle A equation accounts for which factor that Weymouth does not explicitly include?

Accepted Answer

Pipe roughness effects at lower Reynolds numbers

Answer

The Panhandle A equation was developed for partially turbulent flow regimes and includes an efficiency factor that implicitly accounts for friction variation with Reynolds number.

(SPED) Society of Piping Engineers and Designers Certification Practice Test

(SPED) Society of Piping Engineers and Designers Certification Practice Test

SPED Fluid Dynamics & Flow Analysis 3