c) A valve is required to regulate the flow of natural gas. Details of the gas are given in table below. It can be assumed that the pipe size and the valve size are the same [i.e. piping geometry does not have to be allowed for].

The chosen valve type is the V250 rotary ball valve by Fisher Controls International [the V250 data sheet is available on Blackboard].

i) Determine the required valve size in inches from the range of sizes given in the data sheet [the data sheet gives a range of nominal pipe sizes (NPS) in inches].

ii) Estimate the percentage the chosen valve would have to be open to carry the required flow.

Required volumetric flow rate [@ STP] 2.8 x 106 litre per minute

Density [@ STP] 0.752 kg per m3

Specific heat ratio 1.31

Inlet pressure 20 bar gauge

Outlet pressure 6 bar gauge

Inlet Temperature 20 C