Question

In hot water heating systems; How can i do pipe calculations and how can i fill the pipe chart ? Can u tell step by step ? In most general way.

Answer 1

Answer:

Pipe calculations in hot water heating system:

The follwing steps as given below are used for pipe calculation and sizing the pipes in hot water sytems

Total pressure loss in hot water piping system can be given as

= Total pressure loss in the system ()

= Major pressure loss due to friction ()

= Minor pressure loss due to fittings ()

Major pressure loss due to friction in the pipe can be alternatively calculated as

Where

i=Major pipe friction resistance per unit leangth of the pipe ( per meter pipe)

l= length of pipe in meters

In the above terms, friction resistance in case of actual pipes and the volume flows can be calculated or obtained from the pipe charts.

Mminor pressure duw to fittings as elbows, bends, valves can be given or presented as

or can be written as the head loss as

Here

Minor cofficient of friction

= Density of the fuid

= Head loss

v= velocity of flow

g= accleration due to gravity

So above calculation are used for pipe calculation in the hot water heating system.

Filling of pipe charts for hot water heating system:

Filling of pipe charts are being done on the basis of calculation of all the unknown parameters and calculation on the basis of requirement. Size of pipe is specified generally with the two non dimesnional numbers

• Schedule number
• Nominal pipe size

Insude diameter of pipe is calculated with the help of relation between schedule number and nominal pipe size.For different material of pipes different values are available which are used for the calculation.

The following process are being adapted to calculate the various value required to fill the values in pipe charts and the process us as given below

• Haet loss calculation from the spaceor room
• Boiler out put calculation
• Selection of heater unit
• Pump type, duty circulation requiremnt check and selection
• Pipe scheme preperation and calculation of pipe size

From the above terms, we can know all the values required and the values covers the standardisation of the dimesions for the high as well as low temprature and pressure applications

Generally with the help of pipe data chart is used to find the pipe size, diameter of pipe, wall thckness and pressure used in the wroking.

As we shown above that there are two important factors are required for pipe charts filling and in case of schedule number, regardless of this, pipe of a perticular size and having same outside dia. as the schedule number increase the wall thckness also increae and actual bore of the pipe reduces.

For example in case of 4 inch pipe, having schedule number 40 and 80 in two different conditions and if both pipe have outr dia as 4.5 inch so in that case the wall thicknees and the bore will be .237 and 4.026 inches respectively for the first pipe, while in second case it will be .337 and 3.826 inches

So like this with the help of various data we can get the values and same can be filled for pipe chart calculations and filling.