Source: Siemens 2023 | Author: Daniel Henningsen
At Siemens, the ultrasonic flow meter SITRANS FUE380 and the calculator SITRANS FUE950 are certified with type approval according to the Measuring Instruments Directive (MID) under MI-004. This certification allows the measurement to be used for billing purposes. The MI-004 approval specifically applies to heat meters, making it relevant for the SITRANS FUE380 and the FUE950 energy calculator.
Generally, a heat meter consists of one or more devices, including the following components:
- 1x Flow meter
- 1x Energy calculator
- 2x Temperature sensors
This document aims to explain the design of the individual devices, giving customers better insight to ensure they receive the right devices for their tasks.
1. SITRANS FUE 380
The SITRANS FUE 380 is our inline ultrasonic flow meter, certified according to the MI-004 type approval. Similar to the design of flow meters under MI-001 (water meters), the flow limits are relevant here. These limits are , , and (DIRECTIVE 2014/32/EU OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL, 2014).
: lowest value of q that is permissible for the correct functioning of the heat meter
: highest value of q that is continuously permissible for the correct functioning of the heat meter
: highest value of q that is permissible for the correct functioning of the heat meter for a short period
: 105% of
To select a FUE380, and are especially relevant. Depending on the nominal size, an MI-004 variant is available.
Example:
Flow rate: 40 m3/h : DN 65 → Nominal flow rate between and
The flow rate should be below . Short-term higher values are allowed but not suitable for permanent use. Therefore, the flow rate should not be permanently between and .
Additionally, the impulse value and the impulse duration must be considered during the design. The impulse value is given in l/impulse and defines how sensitively the output signal responds to fluctuations in the flow rate, see image. The impulse value cannot be changed afterwards without invalidating the approval. The impulse duration and the impulse value must match the flow rate. The possible combinations are automatically checked by the PIA Life Cycle Portal during the design.
This is crucial because the impulse input of the energy calculator is configured according to the impulse of the flow meter. The impulse value range that the energy calculator FUE950 can process ranges from 1l/impulse to 1000l/impulse.
2. SITRANS FUE950
The SITRANS FUE950 is a computing unit that can be used for cooling and heating applications. During configuration, the impulse value set in the FUE380 must be adopted.
Installation location:
The installation location must also be specified. The reason is that the density must be considered in the calculation of the heat quantity, and this depends on the temperature of the medium. Both warm-side and cold-side installations are possible. In the area of heat quantity measurement, warm-side installation means that the flow meter is installed in the supply line, and cold-side installation means it is installed in the return line. Generally, the flow meter is installed on the cold side.
Like the flow meter, the calculator for billing must be approved. Therefore, the FUE 950 must have an EU type examination certificate.
Like the calculator and the flow meter, the used temperature sensors must also be approved according to MI-004. Therefore, these must also be selected during the configuration of the SITRANS FUE950, see image:
In summary, here is a checklist of questions that should be answered beforehand when designing a measurement system approved for heat quantity billing.
Checklist:
Nominal and Maximum Flow Rate
- Compare the nominal flow rate and select the nominal size based on it.
Impulse Value
- Select the impulse value based on the flow rate. This determines how quickly changes can be reflected in the computation unit.
Temperature Sensor Length
- Two identical pairs of sensors approved according to MI004 are available.
- Always purchase in pairs as both sensors need to be calibrated together.
Installation Location of FUE380
- Possible on the cold side (return) or warm side (flow). Must be specified when designing the FUE950.