IEC 61779-5:1998 pdf download – Electrical apparatus for the detectionand measurement of flammable gases -Part 5: Performance requirements for group l apparatusindicating a volume fraction up to 100 % gas

IEC 61779-5:1998 pdf download – Electrical apparatus for the detectionand measurement of flammable gases -Part 5: Performance requirements for group l apparatusindicating a volume fraction up to 100 % gas.
1.1 This part of IEC 61779 specifies requirements for group II (as defined in part 1) portable. transportable and fixed apparatus for the detection and measurement of combustible gas or vapour concentrations with air. The apparatus, or parts thereof. may be installed or used in potentially explosive atmospheres, other than mines susceptible to firedamp (i.e. group If. The requirements and test methods applicable to the apparatus covered by this standard are specified in part 1.
1.2 This standard is restricted to apparatus intended for the detection and measurement of volume ratios of combustible gas or vapour in air in volume fractions from 0 % to 100 %.
NOTE 1 — Apparatus covered by this standard will noimally be intended to operate in volume ratios greater titan
100% LEL.
NOTE 2 — AJiliough apparatus 01 the types covered by this standard may be Suitable lot deieci.ng a wide range 01 combustible gases, particular gases (ag msthane or propan.l are specih.d in part I as It,. cornpon.nls oh the test gases br th. purpose oh practical convenience. lit. perbormance reQuirements specled In rn,s standard should th,i4o,e be consid*red with caution when the apparatus is used to detect other conibusitble gases. as some parameters — such as time Oh response — well be modIfied.
2 DefInitions
For the purpose of this part of IEC 61779. the definitions given In part 1 apply
3 General requirements
The apparatus shall comply with the general requirements specified in part 1 and with the performance requirements specified In clause 4 of this standard.
Compliance shall be determined in accordance with the appropriate test requirements and methods, including initial calibration, specified in part 1.
It shall be verified that the contents of the manufacturer’s instruction manual are in accordance with the requirements specified in part 1
4 Performance requirements
4.1 General
The normal conditions for tests are specified in 4.3 of part 1. Compliance shall be determined in accordance with the test methods specified in 4.4 of part 1.
4.2 Unpowered storage
After being submitted to the conditions specified in 4,4.2 of part 1, the apparatus shall meet the requirements spec,f ted in 4.3 to clause 5 of this standard.
4.3 Calibration curve (not applicable to alarm-only apparatus)
4.3.1 CalIbration curve
After initial adjustment with the standard test gas, each individual indication in the three sets of indications (after correction using the manufacturer’s calibration curves, if necessary) obtained for each of the tour gas volume ratios distributed over the measuring range, shall not differ from these volume ratios by more than ±5% of the measuring range or ±10 % of the indication. whichever is the greater.
4.3.2 Response to gases other than the test gas
The apparatus indications (after correction using the manufacturers calibration curves, if necessary) obtained for each of the three gas volume ratios of each gas tested shall not differ from these volume ratios by more than ±7% of the measuring range or ±15% of the indication. whichever is the greater.
4.4 StabIlity (continuous duty apparatus)
Continuous duly apparatus shall comply with the following requirements:
a) short-term stability
The short.term variallon shall not exceed ±3 % of the measuring range or ±10 % of the indication, whichever is the greater.
b) long-term stability (fixed and transportable apparatus)
The long-term variation shall not exceed ±7 $ of the measuring range or ±15 $ of the indication, whichever is the greater.
c) long-term stability (portable apparatus)
The long-term variation shall not exceed ±5 % of the measuring range or ±10 % of the indication, whichever is the greater.
4.5 StabilIty (spot-reading apparatus)
The variation of the indication shall not exceed ±3 % of the measuring range or ±10 % of the indication, whichever is the greater.
4.6 Alarm
The alarm(s) shall operate during every cycle of the test. If a latching alarm is provided, the manual reset action shall be checked.