P 119
Gas Detectors Portable Contd.
Let us analyze what is the fundamental difference between Zone'0' and Zone'1' conditions .
As per API/IEC/IS ,
Zone'0'-Hazardous Area that part of the plant hazardous area in which a flammable atmosphere is present continuously or for long period or frequently.
In refinery/ petrochemical complex, that sort of condition prevail only in underground open pits or inside atmospheric tanks or columns/vessels/drums. Yes, all electrical &instrumentation device fixed in those areas have to necessarily meet that zone classification strictly. But when it comes to portable devices to be possessed by each individual , does it call for Zone'0' rating? The answer is big NO for the following reasons:
1) No one is supposed to go to those areas when hydrocarbon inventory is present in that zone area.
2) Assuming somebody has tresspassed into that area without knowledge, the device will go into alarm mode and he has to escape.
3) The fundamental issue of change of zone status will never be noticed and demarkation limit will not be known to anybody.
Zone'1'- Hazardous Area that part of hazardous area in which a flammable atmosphere is likely to occur in normal operation occassionally.
These condition can occur near any equipment/device having several flange joints or valves, where gasket failure or gland packing release develop . That time, it is essential for operations/ maintenance to visit that spot to undertake emergency actions to prevent any unsafe condition in operations/atmosphere. Here only there is an absolute need for a person to possess a bump tested gas detector portable for his/her personal safety. If he carries a zone'1' certified device, the moment he approaches that sensitive area, if there is any flammable gas or toxic gas release present beyond the set alarm limit, the device will go into alarm mode and caution that person. That means that he comes to be cautioned for the change of zone - from normal zone'2' to zone'1' and he can think of emergency steps of operation/escape/evacuation etc.
Under normal operations of a hydrocarbon processing operations only Zone'2' condition will be prevalent. Zone'2' Hazardous Area that part of hazardous area in which a flammable atmosphere is not likely to occur in normal operations and if at all arise, it will persist for a short period only.
That is the condition that normally prevail in the complex where steady state operations take place with good house keeping and having high Reliability Assurance program.
But somehow the CHSEE group could not appreciate the importance of this zone transition indication requirement essentiality between Zone'1' to Zone'0' and through S&OR management insisted to opt for Zone'0' approval only! All these happened since the interested vendors wanted to push their bid. and our team could not understand the essential safety requirement. Because such a mandate has come from the top, we had to abide that for the top-up requirement; but that has created another dispute.
Before going into that aspect, let us look ,how we arrived at the various grouping in each plant area
and how we arrived at the quantity requirement for each plant area and where the bump module for each group have to be located with what gas canister and how many?
For that , one should understand the function of bump module, its configuration and how it functions
& its essentiality for signalling the device status and data gathering etc.
Contd......
Key Aspects :- Incident analysis, Technical issue
Gas Detectors Portable Contd.
Let us analyze what is the fundamental difference between Zone'0' and Zone'1' conditions .
As per API/IEC/IS ,
Zone'0'-Hazardous Area that part of the plant hazardous area in which a flammable atmosphere is present continuously or for long period or frequently.
In refinery/ petrochemical complex, that sort of condition prevail only in underground open pits or inside atmospheric tanks or columns/vessels/drums. Yes, all electrical &instrumentation device fixed in those areas have to necessarily meet that zone classification strictly. But when it comes to portable devices to be possessed by each individual , does it call for Zone'0' rating? The answer is big NO for the following reasons:
1) No one is supposed to go to those areas when hydrocarbon inventory is present in that zone area.
2) Assuming somebody has tresspassed into that area without knowledge, the device will go into alarm mode and he has to escape.
3) The fundamental issue of change of zone status will never be noticed and demarkation limit will not be known to anybody.
Zone'1'- Hazardous Area that part of hazardous area in which a flammable atmosphere is likely to occur in normal operation occassionally.
These condition can occur near any equipment/device having several flange joints or valves, where gasket failure or gland packing release develop . That time, it is essential for operations/ maintenance to visit that spot to undertake emergency actions to prevent any unsafe condition in operations/atmosphere. Here only there is an absolute need for a person to possess a bump tested gas detector portable for his/her personal safety. If he carries a zone'1' certified device, the moment he approaches that sensitive area, if there is any flammable gas or toxic gas release present beyond the set alarm limit, the device will go into alarm mode and caution that person. That means that he comes to be cautioned for the change of zone - from normal zone'2' to zone'1' and he can think of emergency steps of operation/escape/evacuation etc.
Under normal operations of a hydrocarbon processing operations only Zone'2' condition will be prevalent. Zone'2' Hazardous Area that part of hazardous area in which a flammable atmosphere is not likely to occur in normal operations and if at all arise, it will persist for a short period only.
That is the condition that normally prevail in the complex where steady state operations take place with good house keeping and having high Reliability Assurance program.
But somehow the CHSEE group could not appreciate the importance of this zone transition indication requirement essentiality between Zone'1' to Zone'0' and through S&OR management insisted to opt for Zone'0' approval only! All these happened since the interested vendors wanted to push their bid. and our team could not understand the essential safety requirement. Because such a mandate has come from the top, we had to abide that for the top-up requirement; but that has created another dispute.
Before going into that aspect, let us look ,how we arrived at the various grouping in each plant area
and how we arrived at the quantity requirement for each plant area and where the bump module for each group have to be located with what gas canister and how many?
For that , one should understand the function of bump module, its configuration and how it functions
& its essentiality for signalling the device status and data gathering etc.
Contd......
Key Aspects :- Incident analysis, Technical issue
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