3.5kVA Dual-Fuel Generator (Petrol or LPG)

What Is a Dual-Fuel Generator?

A dual-fuel generator is an open-frame petrol generator fitted with an additional LPG carburetor or fuel injection system that allows it to run on LPG from a standard 9kg or 19kg gas cylinder. Switching between fuels typically requires turning off the generator, adjusting a manual valve, and restarting. The dual-fuel design does not require modification or special installation — it ships ready to run on either fuel.

The Load Shedding Advantage

During sustained high-stage load shedding, petrol stations in South Africa often experience long queues, temporary supply shortages, and pumps offline due to the stations’ own power outages. LPG sold in 9kg cylinders is available at Pick n Pay, Checkers, Builders Warehouse, and Afrox depots — outlets with longer trading hours and less affected by fuel supply disruptions. A dual-fuel generator owner can switch to LPG when petrol is scarce and return to petrol when supply normalises — without any loss of backup power coverage.

LPG Performance vs Petrol

On LPG, most dual-fuel generators produce approximately 10–15% less power than on petrol. For a 3.5kVA rated on petrol, expect approximately 2.4–2.6kW on LPG — still sufficient for all standard household load shedding needs. LPG burns cleaner than petrol — reducing carbon deposits in the engine, extending spark plug life, and potentially reducing oil change frequency.

LPG Storage Safety

A standard 9kg gas cylinder contains approximately 9 litres of LPG. Always store LPG cylinders outdoors or in well-ventilated areas, away from naked flames and heat sources. Do not store more than 2 cylinders per dwelling under South African fire regulations.

Safety — Carbon Monoxide

Dual-fuel generators produce carbon monoxide on both petrol and LPG. While LPG combustion is cleaner than petrol, the generator must still be operated outdoors at all times. Never run the generator in a garage, enclosed courtyard, tent, or any space that shares air with occupied rooms. Carbon monoxide is odourless and lethal in concentration.

Frequently Asked Questions

Q: How do I switch between petrol and LPG?
A: Switching is done manually using a fuel selector valve. Turn off the generator, turn the valve to the desired fuel, connect or disconnect the LPG regulator hose as needed, and restart. The process takes under 2 minutes.

Q: Where do I buy LPG cylinders?
A: 9kg and 19kg LPG cylinders are available at Pick n Pay, Checkers, Builders Warehouse, Afrox depots, and most hardware and camping stores across South Africa.

Q: Does running on LPG damage the generator?
A: No. LPG is a recognised generator fuel used worldwide. It is cleaner than petrol and causes less carbon buildup on valves and pistons. Long-term use on LPG does not damage the engine.

Q: Does a 9kg gas cylinder last as long as a tank of petrol?
A: A 9kg cylinder runs a 3.5kVA generator at moderate load for approximately 6–9 hours. A 5-litre petrol tank provides approximately 3–5 hours at similar load. LPG provides longer runtime per unit of stored fuel, though the cylinder is heavier to transport.