Decree No. 381 / 2006 Coll.
Order laying down requirements for temperature sensors used as part of a specified meter
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Order
Effective from 01.10.2006
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01.10.2006
02.08.2006
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381
DECLARATION
of 11 July 2006
laying down requirements for temperature sensors used as part of a specified gauge
The Ministry of Industry and Trade provides pursuant to Sections 6 (2), 9 (1) and 27 of Act No. 505 / 1990 Coll., on Metrology, as amended by Act No. 119 / 2000 Coll. and Act No. 137 / 2002 Coll.:
This decree sets out the requirements for temperature sensors with or without a current or voltage converter used as part of a specified gauge (hereinafter referred to as "temperature sensors'), the type approval procedure and the verification procedure. This Decree was notified in accordance with Directive 98 / 34 / EC of the European Parliament and of the Council of 22 June 1998 laying down a procedure for the provision of information in the field of technical standards and regulations and rules and of rules on information society services, as amended by Directive 98 / 48 / EC.
For the purposes of this decree, temperature sensors shall be considered as:
(a) resistance temperature sensors for heat meters supplied by a heat transfer liquid;
(b) resistance temperature sensors for heat meters supplied by water vapour;
(c) resistance temperature sensors for flow meters.
The terminology, the requirements for temperature sensors, the type approval procedure and the verification procedure are set out in the Annex.
This Decree shall take effect on 1 October 2006.
Minister:
Ing. Urban v. r.
Annex to Decree No 381 / 2006 Coll.
1 TERMINOLOGY
1.1 The sensor is a sensitive part of the temperature sensor (resistor) which reacts to temperature change by changing resistance.
1.2 A member of a heat meter is a part of a heat meter that scans the physical quantities needed to determine the amount of heat or receives and provides mathematical processing of these quantities. The heat meter members are water meters, temperature sensors and calorimetric counter.
1.3. The T0,5 response time is the time interval between the moment when the temperature sensor is exposed to the temperature jump change and the moment when the sensor resistance change thus induced reaches 50% of its steady state.
1.4 The lower temperature range limit is the lowest temperature at which the temperature sensor error is guaranteed.
1.5 The temperature sensor head is the component used to connect the internal line to the connection cable; can be made as a connector or terminal board.
1.6 The upper limit of the temperature range is the highest temperature at which the permissible temperature sensor error is guaranteed.
1.7 A temperature sensor error (static) is the difference between the temperature sensor reading (output signal) and the temperature of its sensor at steady state.
1.8 The nominal resistance of the temperature sensor is the basic resistance of the temperature sensor as determined by the manufacturer's technical conditions.
1.9 The combined heat meter is a measuring instrument which is composed of separable components.
1.10 The compact heat meter is a measuring instrument which does not have separable components.
1.11 The measuring resistance is a resistor designed for temperature sensing, consisting of a skeleton, winding or a layer of material with a defined thermal dependence of electrical resistance and of outlets; is the component of the temperature sensor.
1.12. The heat meter is a measuring instrument designed to measure the amount of heat that is surrendered or taken from the heat transfer device.
1.13 Uncertainty is the estimate assigned to the result of the measurement and characterising the interval of values that are claimed to be within it of the correct value.
1.14. The smallest temperature difference is the smallest temperature difference for which the heat meter is intended and at which permissible errors are not exceeded.
1.15. The protective tube (stem tube) is a component protecting the measuring resistance and internal line from damage. It is finished with a temperature sensor, connector or cable header.
1.16 The platinum temperature resistance sensor is a temperature sensor whose temperature sensor has a platinum element as a sensor.
1.17. The temperature sensor is a structural unit consisting of a measuring resistance, internal line, protective (stem) tube, warhead and, where appropriate, connecting cable.
1.18 The temperature difference is the absolute value of the temperature difference of the heat transfer medium in the supply and return pipes.
1.19. Internal lines are conductors connecting the measuring resistance pins to the temperature sensor head. It can be two-wire, three-wire, four-wire, with a helping loop or with a ground wire.
1.20. The basic resistance R0 is the resistance of the temperature sensor at 0 ° C.
2 TEMPERATURE REDUCTION REQUIREMENTS
2.1. METHOLOGICAL REQUIREMENTS
2.1.1 General
2.1.1.1. The relationship between resistance and temperature can be expressed by the equation:
for range (-200 to 0) ° C
Rt = R01 + A.t + B.t2 + Ct-100 ° Ct3
for range (0 to 850) ° C
Rt = R01 + A.t + B.t2
Where: A = 3,9083.10-3 ° C-1
B = -5,775.10-7 ° C-2
C = -4,183.10-12 ° C-4
2.1.1.2 Resistance values
The temperature sensors shall be so designed that their nominal resistance at 0 ° C is 100, with the exception of the pair temperature sensors, the nominal resistance of which may be 500 or 1000,
2.1.1.3. Allowed errors
Allowed temperature sensor errors are:
| třída | hodnota dovolené chyby v °C |
|---|---|
| A | 0,15 + 0,002 | t | |
| B | 0,30 + 0,005 | t | |
where bf 124; t bn 124; is the absolute temperature value.
Values of class error allowed A does not apply to temperature sensors of 100 ° C at temperatures above 650 ° C.
2.1.2. Specific requirements by type
2.1.2.1. Resistance temperature sensors for heat meters supplied by a heat transfer liquid
The maximum permissible error of the resistance temperature sensor for heat meters supplied by the heat transfer fluid Et is defined by:
Et = ± 0,5 + 3,
the absolute value of the difference between temperature fluid temperatures in the inlet and return branches of the heat exchange device
The latter is the lowest value of the latter at which the heat meter can operate without exceeding the greatest permissible error
The largest permissible error of the resistance temperature sensor for heat meters supplied by the heat transfer liquid Et expresses the relationship between the indicated and conventional right value, which results from the relationship between the difference in temperature resistance sensor data for heat meters supplied by the heat transfer fluid and the difference in temperature.
The relationship between the temperature and the electrical resistance of each individual resistance temperature sensor for heat meters supplied by the heat transfer fluid from the pair shall not differ from the values resulting from the relationship referred to in paragraph 2.1.1.1 using standard values of constants A, B, C by more than 2 ° C.
2.1.2.2. Resistance temperature sensors for water vapour supplied heat meters, resistance temperature sensors for flow meters
The failure of the resistance temperature sensors for the heat meters supplied by the water vapour and temperature sensors for the flow meters shall not exceed the permissible errors values specified in paragraph 2.1.1.3 or specified by the manufacturer.
2.2 TECHNICAL REQUIREMENTS
2.2.1 General
2.2.1.1. Temperature sensors shall meet the following technical requirements:
(a) the stem tube material shall be non-aggressive to the platinum and mechanically resistant even at the highest temperatures for which the temperature sensor is intended;
(b) the tightness of the stem tube shall withstand a pressure of 3,5 MPa;
(c) the prescribed lowest values of the insulation resistance are:
(at rated highest. temperature):
100 MPa at temperature (15 to 35) ° C and 100 V DC DC,
10 MKV in the range (100 to 300) ° C and 10 V DC DC,
2 MKs in the range (301 to 500) ° C and 10 V DC DC,
0,5 Mbps in the range (501 to 850) ° C and 10 V DC DC,
(d) temperature sensors shall be designed to be suitable for use in measurement systems using DC current or AC current with frequencies up to 500 Hz;
(e) temperature sensors may be designed with different configuration of internal conductors (double, tri- and quadruple conductors); the clamps must be clearly marked,
(f) each temperature sensor shall be marked in such a way as to show resistance, class, conductor configuration and temperature range.
2.2.1.2. The manufacturer shall provide the user with the following information for each temperature sensor:
(a) the maximum values of the relevant electrical quantities (e.g. sensor capacity, ground capacity and inductance);
(b) a minimum dive using a temperature sensor;
(c) response time in seconds and medium used;
(d) the self-heating effect of the temperature sensor in ° C / mW; and
(e) the value of the resistance of conductors on two-wire sensors and, at the request of the user of the meter, the value of the resistance of internal conductors for other connections.
2.2.2 Resistance temperature sensors for heat meters supplied by a heat transfer liquid
2.2.2.1. The manufacturer shall provide the user with the following information for each measuring instrument:
(a) type identification;
(b) temperature limits (θmin and θmax);
(c) temperature difference limits (latter),
(d) maximum permissible working pressure for directly mounted gauges (PN class);
e. Electrical connection of measuring instruments (e.g. four or two conductors),
(f) the principle of action;
(g) the maximum effective value of the current of the meter;
(h) dimensions;
(i) installation requirements (for example, for fitting into a pit);
(j) a maximum liquid speed for gauges exceeding 200 mm in length;
(k) the total electrical resistance of the two-wire cable;
(l) minimum draught,
(m) an output signal for a specific activity (type / level); and
(n) response time.
2.2.2.2. Resistance temperature sensors for heat meters supplied by heat transfer liquid, which measure temperature differences in supply and return pipes, resistance temperature sensors for heat meters supplied by heat transfer liquid selected as paired pairs.
Where dimensional tolerances are not specified, values from Table 1 are used.
Table 1 - Tolerances
| Rozměry mm | 0,5 do 3 | přes 3 do 6 | přes 6 do 30 | Přes 30 do 120 | přes 120 do 400 |
|---|---|---|---|---|---|
| Tolerance mm | ± 0,2 | ± 0,3 | ± 1 | ± 1,5 | ± 2,5 |
2.2.2.3 Construction
For pipe sizes up to and including DN 250, the following types of resistance temperature sensors are standardised for heat meters supplied by the heat transfer liquid:
(a) short resistance temperature sensors for heat meters supplied by a heat transfer fluid without a sink - Type DS,
b) long resistance temperature sensors for heat meters supplied by a heat transfer fluid without a sink - Type DL
c) long resistance temperature sensors for heat meters supplied by heat transfer fluid to the pit - Type PL
The resistance temperature sensors for heat meters supplied by the heat transfer fluid referred to in points (b) and (c) may be with the head or with a permanently connected connection line.
The resistance temperature sensor for the heat meter supplied by the heat transfer fluid referred to in point (a) shall have a permanently connected cable outlet.
2.2.2.4 Materials for protective tube and thermometer
The heat sink and temperature absorber protection tube for heat meters supplied by the heat transfer fluid referred to in paragraph 2.2.2.3 (a) and (b) shall be of a material sufficiently strong and corrosion resistant.
2.2.2.5 Dimensions of short resistance temperature sensors for heat meters supplied by a heat transfer fluid without a sink - DS type
The dimensions shall correspond to those shown in Figure 1.
2.2.2.6. Dimensions of long resistance temperature sensors for heat meters supplied by heat transfer fluid without a sink - Type DL
The dimensions shall correspond to those shown in Figure 2.
2.2.2.7 Dimensions of long resistance temperature sensors for heat meters supplied by heat transfer fluid to the pit - Type PL
The dimensions shall be as shown in Figure 3.
2.2.2.8 Dimensions of the thermometer pit
The thermometer is intended only for use with resistance temperature sensors for heat meters supplied by a heat transfer fluid according to paragraph 2.2.2.3 (c). It is designed so that it can be inserted into the wall of a pipe to which the outside was soldered or welded. Only in this case it is interchangeable with a long temperature sensor for mounting without a pit of corresponding nominal length.
The dimensions shall be as shown in Figure 4.
2.2.2.9 The design of short resistance temperature sensors for heat meters supplied by heat transfer fluid without a sink - DS type with regard to installation.
The gauge shall be mounted perpendicular to the direction of flow and the sensor placed in the centre of the pipe. For internal pressures up to PN 16, the gauge shall be designed to be mounted in the connecting part of the pipe.
2.2.2.10 Design of long resistance temperature sensors for heat meters supplied by heat transfer liquid with sink - Type PL and without sink - Type DL with regard to installation
The gauge shall be so installed that the sensor is located in the centre of the pipe.
The gauge shall be designed to be fixed to the following types of installation (for internal pressures up to PN 16):
(a) in a line ≤ DN 50 mounted in a bend with an anti-flow-facing stem using a coating
(b) in a line ≤ DN 50, mounted at an angle of 45 ° with an anti-flow-facing stalk
(c) in pipes DN 65 to DN 250 mounted perpendicular to the direction of flow using the coating
2.2.3 Platinum temperature resistance sensor
2.2.3.1. Specific provisions for two-wire connection of platinum temperature resistance sensors (see Figure 5)
Total electrical resistance of platinum resistance temperature sensor circuit
RC = R1 + R2 + R3
Electrical resistance of platinum resistance temperature sensor R = R1 + R2
Manufacturer specified electrical resistance of the coupling line R3
All calculations use the electrical resistance of the platinum resistance sensor R.
Note - If a four-wire connection of platinum resistance temperature sensors is used, then the electrical resistance values of the coupling line need not be known.
The total electrical resistance of the platinum resistance temperature sensor circuit (see Figure 6) is RC = R1 + R2.
The electrical resistance of the platinum resistance temperature sensor is R = R1 + R2.
In all calculations, the electrical resistance value of the platinum temperature sensor R is used.
Note - If a four-wire connection of the platinum resistance temperature sensors is used, then it is not necessary to know the value of the electrical resistance of the coupling line to the platinum resistance temperature sensor.
2.2.3.2 Resistance characteristics
The mean electrical resistance values of a platinum resistance temperature sensor for heat meters supplied by a heat transfer liquid or water vapour shall be interpolated by the following relationship:
Rt = R01 + A.t + B.t2
where:
Rt is the value of the electrical resistance at t in the h (except the electrical resistance of the coupling line - see Figures 5 and 6)
R0 value of electrical resistance at 0 ° C (baseline) (excluding electrical resistance of the coupling line)
A = 3,9083 × 10-3 ° C-1
B = -5,775 × 10- 7 ° C-2
Note: National temperature ethalons are expected to be implemented according to ITS-90 (International Temperature Scale 1990).
2.2.3.3 Connection lines
Cable conductors may be used for connecting lines or, in the case of platinum resistance temperature sensors, with a wire conductor head. If cable wires are used, then they must have a modified end (for example, by means of an end lead sleeve). The heating of the ends to prevent the cable from dissolving is not permitted. A soldered connection for connecting a platinum resistance temperature sensor to a calorimetric counter shall be permitted only if the platinum resistance temperature sensors are unmistakable.
In the case of shielded cables, platinum resistance temperature sensors shall not have any connection between the shielding and the protective casing.
2.2.3.4 Platinum resistance temperature sensors for two-wire measurement method
The length and cross-section of the conductors of the connecting line of the separable platinum resistance temperature sensors shall be identical.
The length of the coupling line, as indicated by the manufacturer, shall not be changed.
The supply length for platinum resistance temperature sensors shall be within the range specified in Table 2.
Table 2 - Maximum supply lengths for platinum resistance sensors Pt 100
| Průřez přívodu | Maximální délka pro Pt 100 |
|---|---|
| 0,22 mm2 | 2,5 m |
| 0,50 mm2 | 5,0 m |
| 0,75 mm2 | 7,5 m |
| 1,50 mm2 | 15,0 m |
For platinum resistors with higher electrical resistance values, the limits may be increased proportionally.
2.2.3.5 Platinum resistance temperature sensors for the four-wire measurement method
The four-wire connection of platinum resistance temperature sensors shall be used if the cable length requirements set out in paragraph 2.2.3.4 cannot be met.
2.2.3.6. The connections shall be clearly identifiable in such a way that there is no confusion.
For platinum temperature resistors with headers, 0,5 mm2 is recommended and the platinum temperature resistors with cable outlet have a minimum diameter of 0,14 mm2.
2.2.3.7. Response time
The supplier shall specify the response time of the T0,5 platinum temperature sensor as defined in paragraph 3.3.1.3.
2.2.4 The measuring converter shall comply with the specifications given by the manufacturer and shall be installed and ready to operate as instructed by the manufacturer.
APPROVAL
3.1. Procedure for type approval
3.1.1. When applying for type-approval (1), the applicant shall, at the request of the Czech Metrology Institute, submit a free number of meters for testing. Depending on the test procedure, the Czech Metrology Institute can ask the applicant for additional delivery of additional meters.
3.1.2 The Czech Metrology Institute will carry out tests for the type-approval of measuring instruments, including an assessment of the submitted technical documentation.
3.2 Control aids
The following devices shall be used to perform the type-approval test of the gauge:
(a) a preparation for the implementation of a melting point of ice allowing simultaneous testing of at least 5 pieces of temperature sensors and their dives to a depth of at least 200 mm;
(b) a water bath for measuring in the range of temperatures (0 to 95) ° C with a working area of 80 mm or more and a height of 200 mm or more; the temperature field in the working area at all working temperatures shall have no more than 0,02 ° C; the temperature variation in the working area shall be less than 0,02 ° C;
(c) an oil bath for measurements in the temperature range (20 to 300) ° C with a working space of 80 mm or more and a height of 200 mm or more; the temperature field in the working area at all operating temperatures shall be no more than 0,02 ° C and the temperature variation in the working area shall be less than 0,03 ° C;
(d) a salt bath for measurements in the range of temperatures (200 to 600) ° C with a working area of not less than 40 cm2 and a height of not less than 250 mm, a temperature field in the working area at all working temperatures shall not be more than 0,05 ° C and a temperature variation in the working area shall be less than 0,05 ° C; The salt bath shall be equipped with thermometer sinks for inserting temperature sensors, the difference between the diameter of the temperature sensor and the temperature sink may not exceed 1 mm;
(e) an air bath (peak) for measurements in the temperature range (100 to 850) ° C, the upper limit of the temperature range shall be selected according to the requirement of the highest temperature checked; The air bath shall be capable of testing at least two temperature sensors simultaneously, the conformity of temperature between sinks shall not vary by more than (0,05 to 0,5) ° C; the depth of the temperature transducers to the air bath shall be at least 150 mm, the temperature variation in the working area shall not exceed (0,02 to 0,3) ° C;
(f) platinum temperature resistance sensor - secondary first or second order etalon for the required temperature range with approximately the same basic resistance as the test platinum temperature resistance sensors;
(g) measuring devices for measuring resistance (AC or DC current) with range and sensitivity according to the basic resistance of the test temperature sensors and the etalon thermometer, the accuracy class of the resistance measurement device shall be better than 0,01; it shall enable the necessary measurement current size to be set, the uniform measuring device shall be equipped with a commuter of the measuring current and, if possible, the current in the measuring device for measuring resistance. Digital voltmeters or multimeters are recommended; alternating bridges (specially designed for measuring resistance temperature sensors) with range (1000 to 4000) are the most suitable.
(h) an isolation resistance meter with a DC voltage of up to 100 V, the permissible error of which is not more than 10% and a range of not less than 500 MCS;
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Regulation Information
| Citation | Decree No. 381 / 2006 Coll. |
|---|---|
| Regulation Type | Order |
| Author | - |
| Collection | Code of Laws |
| Date of Promulgation | 02.08.2006 |
|---|---|
| Effective from | 01.10.2006 |
| Effective until | - |
| Status | Valid |
The regulation text is for informational purposes only.
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