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For diesel-fired boilers and industrial burners, the oval gear flow meter is the standard choice. It handles diesel viscosity from 2 to 5 cP, gives ±0.5% accuracy without straight pipe runs, and fits the tight space around a burner skid. For most boilers in the 1 to 10 ton/h range, a DN15 to DN40 oval gear meter on the supply line, paired with a second meter on the return line, gives true net fuel consumption. Add a PT100 sensor and pulse output to a flow computer for temperature-compensated billing.
Most diesel applications measure one-way flow. A burner does not. Boilers run with a fuel ring main: the pump pushes more diesel than the burner needs, and the excess flows back to the tank. If you only meter the supply line, you over-count by 20 to 40 percent.
Here's the standard fix. Install one flow meter on the supply line and a second on the return line. Net consumption = supply minus return. Most flow computers and PLCs handle this subtraction directly. We have shipped this setup to bottled water plants in Indonesia, palm oil mills in Malaysia, and textile factories in Bangladesh, all running diesel-fired steam boilers between 2 and 8 ton/h.
Three reasons matter for boiler rooms:
Tight space, no straight runs. Burner skids are packed. A turbine meter needs 10D upstream and 5D downstream of straight pipe. An oval gear meter does not. You can mount it 200 mm from an elbow.,As below picture shows no straight pipeline needed before and after flow meter.
Viscosity tolerance. Return-line diesel is hot, sometimes 60 to 80 °C. Viscosity drops from 4 cP to under 2 cP. A turbine meter's accuracy drifts. Oval gear accuracy stays at ±0.5% across the range.
Works without power. Mechanical register oval gear meters keep totalizing during power cuts, which matters in Nigeria, Pakistan, and most of Sub-Saharan Africa.
Mechanical diesel flow meter
Use this as a starting guide. Confirm with your burner nameplate fuel consumption.
| Boiler / Burner Size | Diesel Consumption | Recommended Meter Size | Typical Model |
| Small burner (100–500 kW) | 10 – 50 L/h (2.6 – 13 GPH) | DN10 – DN15 (3/8"–1/2") | LC-M6, LC-M9 |
| Medium boiler (1 – 3 ton/h steam) | 60 – 250 L/h (16 – 66 GPH) | DN15 – DN25 (1/2"–1") | LC-M12, LC-M25 |
| Large boiler (5 – 10 ton/h steam) | 400 – 800 L/h (105 – 211 GPH) | DN25 – DN40 (1"–1.5") | Oval gear LC series |
| Industrial furnace (>10 ton/h) | 1,000+ L/h (264+ GPH) | DN50+ (2"+) | Oval gear or Coriolis |
Rule of thumb: 1 ton/h of steam needs roughly 70 to 80 L/h of diesel for a well-tuned boiler. A 4 ton/h boiler at full fire pulls about 300 L/h. Size the meter so this point sits at 50 to 70% of the meter's max flow.
Strainer for oval gear flow meter
Most boiler control rooms run on Modbus RTU or 4-20 mA. Our oval gear flow meters come with pulse output as standard, 4-20 mA as option, and Modbus RTU on the digital display version. For automatic burner management systems (Honeywell, Siemens LMV, Weishaupt), the pulse output feeds the burner controller directly. For SCADA reporting, use 4-20 mA or Modbus.
Send us your boiler capacity (ton/h or kW), burner type (dual-fuel, oil-only, atomizing), peak diesel flow (L/h or GPH), supply temperature (°C), whether you have a return line, and required output (pulse, 4-20 mA, Modbus). We will quote the right meter size and seal type within one working day. See our complete diesel flow meter guide for technology comparison, or our oval gear flow meter product page for full specs.
we will contact you within 24 hours..
