PTB Ex Proficiency Testing Program
Interlaboratory comparison - type of protection “d”
(Test Round “d”)
In Test Round “d“, the explosion pressure (reference pressure) is determined in accordance with standard IEC 60079-1 for different configurations of test sample “d“
Test sample “d“:
Test sample “d“ consists of two tubular chamber made of steel which are 250 mm (chamber A) and 500 mm (chamber B) in length and closed by flanges on both sides. The inner diameter amounts to 161.5 mm. The explosion pressure for the chambers is measured separately and in combination with the orifice. For the measurements, thus four configurations result.
Figure A.1: Diagrammatic sketch of test sample "d"
Preparation:
To ensure the comparability, all test samples “d“ will be prepared in advance by PTB; by this, the position of the test borings will be defined uniformly for all the test samples used in Test Round “d“ . Where necessary, the participants must perform additional preparations to adapt the samples to the pressure transducers, ignition sources and gas leads used in their laboratory.
Performance of the test:
The reference pressure P is determined in accordance with IEC 60079-1, section 15.1.2, for four different configurations with two selected gas mixtures specified by the above-mentioned standard.
For each ignition test, the explosion pressure is measured at two positions: on the side of the explosion vessel opposite to the ignition source and on the side of the ignition source.
The mixture shall be ignited by only one ignition source. The type of the ignition source must be indicated in the records.
The explosion pressure is determined with the following configurations of the chambers and the orifice for five ignitions each:
a) Chamber A separately with two gas mixtures (hydrogen 31 %, ethylene 8 %, ignition side 1 or 2)
b) Chamber A combined with B and two gas mixtures (hydrogen 31 %,
ethylene 8 %, ignition side 1 or 2)c) Chamber A combined with B and orifice with two gas mixtures
(hydrogen 31 %, ethylene 8 %, ignition side 1)d) Chamber A combined with B and orifice with two gas mixtures
(hydrogen 31 %, ethylene 8 %, ignition side 2)For all measurements performed, the requirements stated in the above standard and the general requirements of ISO/IEC 17025 must be met.
Figure A.2: Example of Test Sample "d" (Configuration a)
Data acquisition:
The forms for the recording of the measured data and any additional information will be made available electronically. Each participant will receive a model documentation.
All measurement records and forms with the data determined by the participants shall normally be returned online via the Internet platform, they may, however, also be forwarded by e-mail or as hardcopy.
Specialists to be contacted for Test Round “d“:
Physikalisch-Technische Bundesanstalt (PTB)
Bundesallee 100
D-38116 Braunschweig
Joachim Kühne
E-mail: joachim.kuehne@ptb.de
Phone: (+49)531-592-3554
Dipl.-Ing.(FH) Jörg Flötotto
E-mail: joerg.floetotto@ptb.de
Phone: (+49)531-592-3599
Annex B
PTB Ex Proficiency Testing Program
Interlaboratory comparison - type of protection “i”
(Test Round “i”)
Comparison of the ignition capability of different test circuits with the spark test apparatus in accordance with IEC 60079-11, Annex B, by means of practical ignition tests
For the performance of practical ignition tests on electric circuits, the spark test apparatus described in IEC 60079-11, Annex B, is used. However, the test conditions defined there may lead to significant deviations in the test results. Especially large deviations can be found in the case of specific types of mixed circuits and in the case of circuits with dynamic behaviour (e.g. electronic current limiter, crowbar circuits and others).
However, to achieve internationally comparable and reproducible ignition results, possible error sources must be detected and analyzed. This is why the ignition probabilities of different spark test apparatuses shall be determined for defined circuits by interlaboratory comparison measurements performed by selected test institutions. In Test Round "i", additional test circuits with dynamic behaviour will be investigated and compared on the basis of the simple circuits (such as resistive, inductive, capacitive or mixed circuits) described in the standard. A total of twelve circuits shall be tested: seven simple and mixed circuits and five circuits with dynamic behaviour. Here, the test conditions will be defined considerably more precisely than in IEC 60079-11.
The interlaboratory comparison thus allows systematic and random error sources to be detected, corrections of the normative regulations (IEC 60079-11) - were appropriate - to be prepared and instructions to be harmonized as a measure for quality improvement.
Test box “i“:
Test box "i“ must be regarded as a black box which accommodates all twelve test circuits to be connected manually, including the required energy supplies.
The ignition behaviour of five circuit types of different dimensionings is tested in twelve ignition tests. The circuits are permanently installed in test box “i“ for determination of the ignition probabilities:
Table B. SEQ Table_B. \* ARABIC 1: Circuits of test box "i"
No.
Circuit types
1.
1a
resistive (dimensioning A)
2.
1b
resistive (dimensioning B)
3.
2
inductive
4.
3a
capacitive (dimensioning A)
5.
3b
capacitive (dimensioning B)
6.
4a
mixed resistive – inductive – capacitive (dimensioning A)
7.
4b
mixed resistive – inductive – capacitive (dimensioning B)
8.
5a
electronic current limiter (dimensioning A)
9.
5b
electronic current limiter (dimensioning B)
10.
5c
electronic current limiter (dimensioning C)
11.
5d
electronic current limiter (dimensioning D)
12.
5e
electronic current limiter (dimensioning E)
Test box “i“ will be made available to all participants by the coordinator. The box is designed as a “black box“. The twelve circuits permanently installed in the “black box“ guarantee homogeneity and stability, as they cannot be changed during the entire test round. The dimensioning of the single circuits and the values for the electrical parameters on which the measurements are based will also be specified by the coordinator and will not be known until the test round is completed. By this, it shall be achieved that during the entire test round, the measurements will not be influenced by subjective expectations and assumptions.
In test box “i“, the single circuits will be connected to the output of the spark test apparatus by means of relays. A detailed process description for operation of test box “i“ is made available by the coordinator together with test box “i“
Figure B.1: Test box "i" (under construction)
Preparation:
For Test Round “i“, no special preparations must be made by the participants - except for the provision of the spark test apparatus with the test gas supply connected. For all ignition tests, tungsten wires which have been uniformly prepared in advance by PTB will be made available. Only these wires may be used for the tests!
Performance of the ignition tests with the spark test apparatus:
The ignition probabilities are determined for each of the twelve circuits by means of a spark test apparatus in accordance with IEC 60079-11, Annex B, with a gas mixture of group IIC, Table 7, with 21±2 % hydrogen in air with the safety factor 1.0.
The participants describe the concrete realization of the gas mixture preparation in their laboratories.
(Reply to the question: How is the test gas mixture composed in practice?)
Before each test, the spark test apparatus must be calibrated with the test circuit – the result must be documented.
For each one of the 12 tests, new (fresh) tungsten wires must be used. The number of contactings (alternatively: the time) until ignition must be recorded. For each one of the 12 test circuits, 20 ignitions must be realized.
If - after 1000 revolutions (4000 contactings) - no ignition is possible, the tungsten wires must be exchanged and the spark test apparatus be recalibrated with the test circuit. After that, the test must be repeated. After a total of 3000 revolutions without ignition, the test of this circuit must be stopped.
Data acquisition:
The forms for the recording of measured data and any additional information will be made available electronically. Each participant will receive a model documentation. Normally, all measurement records and forms with the data determined by the participants shall be returned online via the Internet platform; they may, however, also be returned by e-mail or as hardcopy.
To be returned to the coordinator after completion of the measurements:
12 measurement protocols of the (12x20) 240 ignition tests of all circuits;
- a description of the gas mixture preparation;
- one or two photos showing the condition of the cadmium disk used (1 x total view and 1 x close-up view of the disk);
- one photo of the spark test apparatus;
- one photo of the device for gas mixture preparation;
- test box “i“
Specialists to be contacted for Test Round “i“:
Physikalisch-Technische Bundesanstalt(PTB) Bundesallee 100
D-38116 Braunschweig
Dr. Udo Gerlach
E-mail: udo.gerlach@ptb.de
Phone: (+49)531-592-3620
Dipl.-Ing.(FH) Thomas Uehlken
E-mail: thomas.uehlken@ptb.de
Phone: (+49)531-592-3543
Annex C
PTB Ex Proficiency Testing Program
Declaration of participation
Information about the participant:
Test laboratory:
Address:
Person to be contacted:
Phone:
E-mail:
Person to be contacted
Test round “d“:
Person to be contacted
Test round “i“:
We will participate in the PTB Ex Proficiency Testing Program (pilot phase) in test round/s
Intrinsic safety “i”:0 Flameproof enclosure “d”:0
Date: ____________________ Signature: ____________________
The filled-in “Declaration of participation in the PTB Ex Proficiency Testing Program” must be returned to the coordinator (e-mail: ex-proficiency-testing@ptb.de) before the middle of March 2010. The receipt of the declaration of participation will be confirmed by the coordinator
Annex D
PTB Ex Proficiency Testing Program
Time Schedule
