LPG & Natural Gas Piping Lab
Add up the gas appliances, apply diversity, then size the main and every branch for the pressure drop you can afford, for LPG or natural gas at low or medium pressure. Size the LPG cylinder bank or bulk tank for vaporisation and autonomy, check separation distances and run through the Civil Defence and AS/NZS 5601 rules.
How to use: pick the gas and pressure, list the appliances with their branch lengths, set the main run. Tap i on any input for help.
1. Inputs
2. Gas system
Schematic with pipe sizes, a 3D view of storage and building, and the tank level between deliveries.
3. Checks
4. Main and branch sizes
Smallest size that keeps the total drop to each appliance within the allowance.
5. Main pipe, every size
6. How it works
Load and diversity
Each appliance is listed by its gas input from the rating plate. A commercial kitchen rarely runs every burner at full rate, so a diversity factor applies to the main (often 70 to 100% for kitchens, much lower for many apartments). Branches to single appliances use the full rate.
Pressure drop
Low pressure LPG is usually 37 mbar in the Gulf and UK practice (2.75 kPa in AS/NZS 5601), natural gas 21 mbar (1.13 kPa in AS/NZS 5601). Only a small drop is allowed to the appliance, typically 1 mbar for natural gas and 2.5 mbar for LPG. Medium pressure distribution (for example 0.7 to 2 bar) carries the gas around a building in small pipes, with a regulator at each unit or kitchen. The lab uses Darcy-Weisbach with the gas density at the working pressure.
LPG storage
LPG must boil off as vapour as fast as it is used. A cylinder can only supply so much continuously before it chills, so banks are sized on vaporisation, with a duty and a standby side and an automatic changeover. Bulk tank vaporisation depends on the wetted surface and the ambient temperature. Storage is filled to 80% and reordered at about 20%, so 60% of the water capacity is usable.
Safety rules
The UAE Fire and Life Safety Code asks for central gas systems by approved contractors, no LPG storage in basements, gas detection with automatic shut off valves in kitchens, an emergency shut off outside the building and pressure testing before use. In New Zealand and Australia, AS/NZS 5601.1 and AS/NZS 1596 apply with certified gasfitters.
Concept sizing tool. Final design, separation distances and approval come from the gas contractor, the gas supplier and Civil Defence or the gas regulator.