Thermal Oil Heat Meter – kW and Mcal Measurement up to 400 °C

A thermal oil heat meter measures oil flow together with supply and return temperatures to calculate heat output (kW, Mcal/h) and total heat consumed (MWh, Mcal) by each dryer, press or cooker. You learn exactly how much heat each product uses, spot losses and optimise the heater in line with ISO 50001 energy management.

ISE thermal oil heat meter system

How a thermal oil heat meter works

The energy calculator takes three inputs: oil volume flow qv, supply temperature T1 and return temperature T2 (a matched Pt100 pair). Heat output: P = qv · ρ · cp · (T1 − T2), where density ρ and specific heat cp are taken at actual temperature for the specific oil in use.

Thermal oil heat meter system: flow sensor, supply and return temperature sensors, energy calculator
Figure 1. Thermal oil heat metering: return-line flow sensor, T1/T2 sensors and energy calculator.

Specifications

Parameter Value
Size DN25 – DN500
Operating temperature Up to 400 °C
Operating pressure PN25
Accuracy ±1 %
Display Oil flow (m³/h), supply and return temperature (°C), heat rate (Mcal/h), total heat (Mcal)
Outputs 4–20 mA, Modbus RTU RS485
Monitoring Online by phone or PC: values, alarms, history

Calculating thermal oil heat

Example: 50 m³/h oil, 280 °C supply, 260 °C return, ρ ≈ 800 kg/m³, cp ≈ 2.5 kJ/kg·K → P ≈ 556 kW ≈ 478 Mcal/h, about 13.3 MWh per day in continuous operation. Because ΔT is often only 15–30 K, temperature error dominates: use a matched class A Pt100 pair per EN 60751 in correctly sized thermowells.

Thermal oil heat calculation from flow, density, specific heat and ΔT
Figure 2. Typical mineral thermal oil properties versus temperature and a worked heat calculation.

Installation

  • Fit the flow sensor on the cooler return line with the straight runs the manufacturer specifies.
  • T1 on supply, T2 on return, close to the consumer; insulate the sensor points.
  • Load the correct ρ and cp tables for the oil into the calculator.
  • Design and operate the thermal oil system to DIN 4754-1; pressure parts must comply with PED 2014/68/EU.

Applications

Heat delivered to dryers, wood presses, cookers, textile dyeing machines and bitumen tanks; energy cost allocation by workshop; heater efficiency checks together with our temperature sensors. For steam, use a vortex steam flow meter with P/T compensation.

Reference standards

Standard Scope
EN 1434-1…-6 Heat meters – calculator principle and paired temperature sensors (written for water; for oil the calculator uses oil properties)
EN 60751 Pt100 temperature sensors
DIN 4754-1 Heat transfer installations using organic fluids
2014/68/EU (PED) Pressure equipment
EN 61326-1 Electromagnetic compatibility
ISO 50001 Energy management systems

FAQ

Can a water heat meter be used for oil?

No: water meters use water ρ and cp and are usually limited below 150 °C. Thermal oil needs a 300–400 °C flow sensor and a calculator loaded with oil properties.

How do Mcal/h and kW convert?

1 kW ≈ 0.86 Mcal/h; 1 Mcal/h ≈ 1.163 kW.

Contact EQUIPMENT INDUSTRIAL SOLUTION CO., LTD (ISE) – Sales +84 909 617 185 – Technical +84 979 117 185 – [email protected].

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