Gas pipe sizing is crucial to the correct performance of the connected gas appliances, pipe must be sized correctly to provide enough gas to each appliance under all conditions.

STEP 1

Sketch pipe layout and add total appliance MJ/h ratings together for a total installation load. 56 + 184 + 34 + 30 = 304 MJ/h

STEP 2

Identify the pipe path with the biggest load. (A-G) and calculate the length of the path in metres.
12 + 2 + 6 + 2 = 22m

STEP 3

Consult the appropriate KemPex Gas Pressure loss chart (this example uses Chart #3 – 2.75 kPa with .275kPa or 10% pressure drop) and find the equal or greater metres value for STEP 2 along top of chart (22 metres).

Take the total rating from STEP 1 which was 304 MJ/h and look down the chart until you locate the equal or next highest MJ/h rating (410 MJ/h). The far right hand column indicates the fittings allowance factor (0.5).

STEP 4

Calculate the number of fittings on the (A-G) pipe run, in this case 5 fittings were used. Now multiply the fittings factor in STEP 3 by the number of fittings used (5 x .5 = 2.5 metres). Add 2.5 metres to your original pipe run length, 22m + 2.5 m = 24.5m Note Every fitting in the pipe run should be included except straight joiners.

STEP 5

Now using the new pipe length of 24.5 metres, find the equal or next highest metres value on Chart #3 as in STEP 3 (25m) and look down the chart until you locate the equal or next highest MJ/h rating (382 MJ/h). Look at the left hand column to determine the correct pipe size for this run (32mm). You have just sized run (A-G).

STEP 6

Using the same 25 metre portion of the Chart #3, match the MJ/h ratings flowing through each section of pipework to the equal or next highest MJ/h rating in the chart to determine the individual pipe size for each section.

STEP 1. SKETCH PIPE LAYOUT

STEP 2. PIPE PATH BIGGEST LOAD

STEP 3. KEMPEX GAS
PRESURE LOSS CHART

PIPE SIZING USER GUIDE V2.0