AS 26142:2020 pdf free.Hydrogen detection apparatus – Stationary applications (ISO 26142:2010 (ED 1.0) MOD).
4 General requirements
4.1 Construction
4.1.1 General
The hydrogen detection apparatus designed to be used in a hazardous area shall comply with IEC 60079-0 and the relevant parts of IEC 60079.
4.1.2 Enclosure
If the application demands it, all parts of the enclosure shall be constructed of corrosion-resistant materials or be protected against corrosion.
4.1.3 Measuri Jig range
The measuring range of the hydrogen detection apparatus shall be declared by the manufacturer. The measuring range shall cover a minimum of one order of magnitude. If the hydrogen detection apparatus uses two or more hydrogen sensor technologies or principles to cover a wide measuring range, the manufacturer shall declare the number of hydrogen sensors and/or specify the measuring range pertaining to each hydrogen sensor technology or principle.
4.1.4 Alarm system
4.1.4.1 Alarm
The hydrogen detection apparatus shall have at least one latching alarm with a fixed or adjustable alarm set point. If two or more alarm set points are provided, the lower may be non-latching, based on user preference. While the alarm condition is still present, the hydrogen detection apparatus shall be designed in such a way that any alarms, except for optional audible alarms, shall remain in operation. Alarm devices shall be tamper-proof.
At least one alarm set point shall be available at or below a hydrogen volume fraction in air of I x 10-2.
4.1.4.2 Fault signals
The hydrogen detection apparatus shall provide a fault signal in the event of loss of power. A short circuit or open circuit in the connection to any remote hydrogen sensor shall also be indicated by a fault signal. An aspirated hydrogen detection apparatus shall indicate the adequacy of flow conditions and produce a fault signal in the event of a flow failure.
4.1.5 Indicators
4.1.5.1 Power indication
The detection apparatus shall provide a visual power indicator that clearly indicates if the power to the hydrogen detection apparatus is on or off.
4.1.5.2 Signals for recording
For a hydrogen detection apparatus where the resolution of the read-out device is inadequate to demonstrate compliance with this International Standard, the manufacturer shall identify suitable points for connecting, indicating or recording devices for the purpose of testing the compliance of the hydrogen detection apparatus with this International Standard.
4.1.5.3 Measuring range
Any under-range or over-range measurements shall be clearly indicated.
If the hydrogen detection apparatus covers more than one measuring range, the measuring range selected shall he clearly identified.
All indications may be shown on the separate control unit.
4.1.5.4 Indicating colours
If only one indicating light is provided for alarm, fault or other indications, it shall be red in colour. If separate indicating lights are used, the colour shall be used in the following order of priority:
a) red for alarm indication;
b) yellow for fault indication; c) green for operation.
In addition to the colour requirements, the indicator lights shall be labelled to show their functions.
4.1.6 Adjustments
All adjustment devices shall be designed so as to discourage unauthorized or inadvertent interference with the hydrogen detection apparatus. Examples would include procedural devices such as a keyboard instrument, or mechanical devices such as a cover requiring the use of a tool.
A fixed explosion-protected hydrogen detection apparatus or hydrogen sensor housed in explosionprotected enclosures shall he designed so that, if any facilities for adjustment are necessary for routine recalibration and for resetting or similar functions, these facilities shall be externally accessible. The means for making adjustments shall not degrade the explosion protection of the hydrogen detection apparatus or hydrogen sensor.
The adjustments of the zero and signal amplification shall be so designed that adjustment of one will not affect the other.AS 26142 pdf download.