Ad ition of tec nical o tion These are c an es whic ad new or modif y existin tec nical req irements, in a way that new o tion are given, but without in re sin req irements f or eq ipmen
Aspirated equipment
Attach the equipment to the test rig as shown schematically in Figure B.1
The test rig features two gas lines: one for clean air and the other for test gas These flows can be alternated between the equipment inlet and the exhaust, ensuring that while one flow is directed to the equipment, the other is sent to the exhaust It is essential that the switching of these flows occurs simultaneously.
The gas line connecting the test rig to the equipment should have an outlet for excess gas
The volume of the gas line connecting the test rig to the equipment should be kept to a minimum
The outlet for excess gas should be closed
The flow rates of the two gas lines should be set to the minimum flow rate specified in the instruction manual
The response time measurement begins when switching from clean air to the test gas It is essential to adjust this response time to account for the switching duration between the gas lines and the time required to purge the dead volume between the switching device's outlet and the equipment's inlet.
The outlet for excess gas should be opened
To ensure optimal performance, the gas inlet to the equipment must be properly restricted, maintaining a flow rate that is 10% above the threshold at which the flow failure signal is triggered.
To prevent reverse flow in gas lines, it is essential to set the flow rates correctly The outlet's excess flow rate should be at least 20% higher than the required rate to ensure safe operation.
The response time measurement begins when transitioning from clean air to the test gas It is essential to adjust the response time to account for the switching duration between the gas lines and the time required to purge the dead volume between the switching device's outlet and the equipment's inlet.
Figure B.1 – Schematic example of test rig for use with aspirated equipment
Equipment that samples by diffusion
Calibration mask method
This method should only be used for measuring response times of "other gases" (5 3.2) in order to compare the response times of different gases
The test rig described in B 1 1 should be used The test should be performed as for equipment without an internal pump (see B 1 2)
To ensure optimal performance, the flow rate through the mask must be adjusted to the minimum flow rate indicated in the instruction manual In cases where only a nominal flow rate is provided, it is essential to utilize this nominal flow rate.
Diffusion or flow methods
The diffusion and/or flow method should be used for measuring the time of response of the equipment for the standard test gases according to 5.4 1 5
A suitable method should be used which has been validated Examples are diffusion (by immersion or containment) or flow methods d etecti on Gas eq ui pmen t Gas inlet
Ou tl et of swi tchi ng d evi ce
I EC 60050, International Electrotechnical Vocabulary (IEV)
I EC 60529, Degrees of protection provided by enclosures (IP Code)
I EC 60079-1 , Explosive atmospheres – Part 1: Equipment protection by flameproof enclosures
I EC 60079-2, Explosive atmospheres – Part 2: Equipment protection by pressurized enclosure
IEC 60079-5, Explosive atmospheres – Part 5: Equipment protection by powder filling “q”
I EC 60079-6, Explosive atmospheres – Part 6: Equipment protection by liquid immersion "o" IEC 60079-7, Explosive atmospheres – Part 7: Equipment protection by increased safety "e"
IEC 60079-1 0-1 , Explosive atmospheres – Part 10-1: Classification of areas – Explosive gas atmospheres
I EC 60079-1 1 , Explosive atmospheres – Part 11: Equipment protection by intrinsic safety "i"
I EC 60079-1 5, Explosive atmospheres – Part 15: Equipment protection by type of protection
IEC 60079-1 8, Explosive atmospheres – Part 18: Equipment protection by encapsulation “m” IEC 60079-25, Explosive atmospheres – Part 25: Intrinsically safe electrical systems
I EC 60079-26, Explosive atmospheres – Part 26: Equipment with equipment protection level (EPL) Ga
IEC 60079-29-2, Explosive atmospheres – Part 29-2: Gas detectors – Selection, installation, use and maintenance of detectors for flammable gases and oxygen
IEC 60079-29-3, Explosive atmospheres – Part 29-3: Gas detectors – Guidance on functional safety of fixed gas detection systems
I EC 60079-29-4, Explosive atmospheres – Part 29-4: Gas detectors – Performance requirements of open path detectors for flammable gases
ISO 61 42, Gas analysis – Preparation of calibration gas mixtures – Gravimetric method
ISO 61 45-1 , Gas analysis – Preparation of calibration gas mixtures using dynamic volumetric methods – Part 1: Methods of calibration
ISO 61 45-2, Gas analysis – Preparation of calibration gas mixtures using dynamic volumetric methods – Part 2: Volumetric pumps
ISO 61 45-4, Gas analysis – Preparation of calibration gas mixtures using dynamic volumetric methods – Part 4: Continuous syringe injection method
I SO 61 45-5, Gas analysis – Preparation of calibration gas mixtures using dynamic volumetric methods – Part 5: Capillary calibration devices
I SO 61 45-6, Gas analysis – Preparation of calibration gas mixtures using dynamic volumetric methods – Part 6: Critical orifices
I SO 61 45-7, Gas analysis – Preparation of calibration gas mixtures using dynamic volumetric methods – Part 7: Thermal mass-flow controllers
ISO 61 45-9, Gas analysis – Preparation of calibration gas mixtures using dynamic volumetric methods – Part 9: Saturation method
I SO 61 45-1 0, Gas analysis – Preparation of calibration gas mixtures using dynamic volumetric methods – Part 10: Permeation method