ISA TR12.13.03

Combustible gas detection used for process safety management mayalso be used to provide protection from explosion or fires byminimizing the possibility of an accumulation of combustible gasesreaching ignitable levels. Criteria are developed to establishcombustible gas levels to initiate alarms, initiate increase inventilation rates and to initiate shutdown of processes to shutoffthe flow of combustible gas that has breached containment. It isthe intent of this document to compile and refine techniques forthe use of combustible gas sensors and controllers to monitor andcontrol sources of combustible gas release into the atmospherewithin designated spaces. It is also the intent that these productsand techniques be adapted by industries and used with processesthat have historically not employed combustible gas detection as amethod of protection.

This document provides guidance on the use of a combustible gasdetection system as a method of protection in Class I hazardous(classified) locations as defined within the following specificdocuments:

• ANSI/NFPA 70 (NEC) where for specific applications, electricalequipment that would not otherwise be permitted in the hazardous(classified) location may be used in conjunction with combustiblegas detection equipment;

• API RP 500 and API RP 505 for the use of combustible gasdetection equipment to augment ventilation to ensure adequatedilution of combustible gas to prevent the possibility ofignition;

• Title 29 Code of Federal Regulations 1910.119(k) OSHAregulations to support the hot work permit.

NOTE 1 — Applicable combustible gas detection equipmentperformance standards include ANSI/ISA-12.13.01 and ANSI/FM6325/ISA-12.13.04.

For the purpose of this document combustible gases includecombustible and flammable gases and vapors.

Documents other than API RP 500 and RP 505 that describe areaclassification techniques, but which have not included combustiblegas detection as part of the process to reduce the probability ofignition are ANSI/NFPA 497 and ANSI/ISA-TR12.24.01 (IEC 60079-10Mod). Application of combustible gas detection and control asdescribed in this document can provide additional protection fromfire and explosion over typical area classification protectiontechniques by risk reduction methods. Industries that use these andother area classification documents can benefit by application ofthe techniques and criteria presented in this document.

NOTE 2 — Where mandatory text is provided in this TechnicalReport, the basis of the mandatory text is derived directly fromreferenced standards.

This document provides guidance on the use of portablecombustible gas detection apparatus to allow live maintenance onequipment or work with electrical powered tools within hazardous(classified) locations.

This document provides guidance on the use of combustible gasdetection as a supplement in adequately ventilated spaces.

For the purpose of this document, apparatus includes

fixed apparatus;

portable apparatus; and

transportable apparatus.

This document is NOT intended to cover the following:

a) Guidance on area classification

b) Apparatus intended only for the detection of non-combustibletoxic gases

c) Apparatus of laboratory or scientific type intended only foranalysis or measurement purposes

d) Apparatus intended for mining applications

e) Apparatus intended for applications in explosives processingand manufacture

f) Apparatus intended only for process control applications

g) Apparatus intended for the detection of a potentiallycombustible atmosphere resulting from dust or mist in air

h) Appartus intended for confined space entry.

Combustible gas hardware as described in this document may beapplied as stand alone sensor/controllers or may be incorporatedwith or into another system such as, Basic Process and ControlSystem (BPCS), Safety Instrumented System (SIS) or Fire and GasSystem that may be employed in an industrial facility. Whenventilation rates must be controlled by the various responses ofthe combustible gas detection and control devices, there must alsobe interaction with the HVAC control system or devices.

Edition:

09

Published:

12/14/2009

ANSI:

ANSI Approved

Number of Pages:

32

File Size:

1 file , 150 KB