<차례>
1. 防爆의 一般····························································································································································· 1
① 폭발이란? ······················································································································································ 1
② 연소의 3요소·················································································································································· 1
③ 방폭이란?························································································································································ 1
④ 방폭의 방법····················································································································································· 2
2. 방폭기기의 표기····················································································································································· 2
1) IEC········································································································································································· 2
① 방폭구조의 종류············································································································································· 3
② 기기의 분류····················································································································································· 3
③ 폭발성 가스의 분류······································································································································· 4
④ 최고표면온도와 온도등급····························································································································· 5
⑤ IP등급 ······························································································································································ 6
2) NEC······································································································································································· 7
① 위험물질의 분류 (CLASS)··························································································································· 7
② 위험장소의 분류 (DIVISION)······················································································································ 7
③ 위험물질의 종류 (GROUP) ······················································································································ 8
3. 위험장소별 방폭구조 적용··································································································································· 8
① 위험장소 구분················································································································································· 9
② 본질안전방폭구조의 종류····························································································································· 9
③ 분진의 종류····················································································································································· 9
1. 防爆의 一般
① 폭발이란?
: 기체의 체적이 급격히 팽창하여 압력이 급상승하는 연소의 일종.
② 연소의 3요소
◎ 가연성물질 - 타는 물질, 가스, 분진 등
◎ 산소 - 공기중에 포함
◎ 점화원 - 열, 전기적 에너지, 기계적 에너지,
(가연성물질과 산소가 혼합되어 있는 상태 : 폭발성 위험분위기)
③ 방폭이란?
: 점화원이 발생하지 않도록 하는 것,
점화원이 위험분위기와 만나지 않도록 하는 것.
④ 방폭의 방법
점화원의 격리
- 점화원 부분을 가연성물질과 접촉하지 못하게 함. (유입, 압력)
- 내부에서 발생한 폭발이 외부로 전달되지 않도록 함. (내압)
설비의 안전도 증강
- 고장시 점화원이 되는 설비에 적용
- 고장이 발생할 확률을 0으로 낮춤. (안전증)
본질적 억제
- 최소착화에너지 (본질안전)
2. 방폭기기의 표기
1) IEC : Ex d IIB T4 IP44
(현재 국내 및 일본, 유럽지역에서 사용)
<방폭표기의 의미>
Ex |
d |
II |
B |
T4 |
IP44 |
방폭기기 |
방폭구조 |
기기분류 |
가스등급 |
온도등급 |
보호등급 |
|
|
|
|
|
|
방폭기기
|
내압 방폭구조
|
산업용
|
가스등급 B
|
최고표면온도100℃ 초과 135℃ 이하 |
∅1mm의 고체 와 튀기는 물 에 대해 보호 |
① 방폭구조의 종류
방폭구조 |
정 의 |
기 호 |
내압 방폭구조 |
용기내 폭발시 용기가 폭발압력을 견디며, 접합면, 개구부 통해 외부에 인화될 우려 없는 구조 |
Ex d |
압력 방폭구조 |
용기내에 보호가스를 압입시켜 폭발성 가스나 증기가 용기내부에 유입되지 않도록 된 구조 |
Ex p |
안전증 방폭구조 |
정상운전중에 점화원 발생방지위해 기계적, 전기적 구조상 혹은 온도상승에 대해 안전도를 증가한 구조 |
Ex e |
유입 방폭구조 |
전기불꽃 아크, 고온 발생부분을 기름으로 채워 폭발성 가스 또는 증기에 인화되지 않도록 한 구조 |
Ex o |
본질안전 방폭구조 |
정상시 및 사고시(단선, 단락, 지락)에 폭발 점화원 (전기불꽃,아크, 고온)의 발생이 방지된 구조 |
Ex ia Ex ib |
비점화 방폭구조 |
정상동작시 주변의 폭발성 가스 또는 증기에 점화시 키지 않고 점화가능한 고장이 발생되지 않는 구조 |
Ex n |
몰드 방폭구조 |
전기불꽃, 고온발생부분을 콤파운드로 밀폐한 구조 |
Ex m |
충전 방폭구조 |
전기불꽃 등 발생부분을 용기내에 고정시키고 주위를 충전물질로 충전하여 가스의 유입, 인화를 방지한 구조 |
Ex q |
특수 방폭구조 |
기타의 방법으로 폭발성 가스 또는 증기에 인화를 방지시킨 구조 |
Ex s |
특수방진방폭구조 |
틈새, 접합면 등으로 분진이 용기내부에 침입하지 않도록 한 구조 |
Ex SDP |
보통방진방폭구조 |
틈새, 접합면 등으로 분진이 용기내부에 침입하기 어렵게 한 구조 |
Ex DP |
방진특수방폭구조 |
기타의 방법으로 방진방폭성능이 확인된 구조 |
Ex XDP |
② 기기의 분류
I : 탄광용
II : 공장 및 산업용
③ 폭발성 가스의 분류
폭발성 가스의 분류 |
A |
B |
C |
최대안전틈새범위 (내압) |
0.9mm 이상 |
0.5mm 초과 0.9mm 미만 |
0.5mm 이하 |
최소점화전류비 (본질안전) |
0.8 초과 |
0.45 이상 0.8 이하 |
0.45 미만 |
적용기기 (내압, 본질안전, 비점화) |
IIA |
IIB |
IIC |
대표적 가스 |
암모니아, 일산화탄소, 벤젠, 아세톤, 에탄올, 메탄올, 프로판 |
부타디엔, 에틸렌, diethyl ether, 에틸렌옥사이드, 도시가스 |
아세틸렌, 수소, 유화탄소 |
☆ 예전의 국내분류
- 폭발성 가스를 발화도 및 폭발등급에 따라 세분
☆ 예전의 국내에서의 폭발등급 분류
폭발등급 |
1 |
2 |
3 |
기준 |
0.6mm 초과 |
0.4mm초과 0.6mm이하 |
0.4mm이하 |
④ 최고표면온도와 온도등급
최고표면온도의 범위 (℃) |
온도등급 |
300 초과 450 이하 |
T1 |
200 초과 300 이하 |
T2 |
135 초과 200 이하 |
T3 |
100 초과 135 이하 |
T4 |
85 초과 100 이하 |
T5 |
85 이하 |
T6 |
☆ 예전의 국내에서의 발화도 분류
발화점의 범위 (℃) |
발화도 |
450이상 |
G1 |
300이상 450미만 |
G2 |
200이상 300미만 |
G3 |
135이상 200미만 |
G4 |
100이상 135미만 |
G5 |
⑤ IP등급
|
첫째숫자 (분진) |
둘째숫자 (물) |
기타기호 (숫자보다엄격) |
|
0 |
무방호 |
무방호 |
A |
손침입 방호 |
1 |
∅ 50mm의 고체 (손) 침입 방호 |
수직으로 떨어지는 물방울 |
B |
손가락침입 방호 |
2 |
∅ 12.5mm의 고체 (혹은 손가락) 침입방호 |
수직에서 최대 15°로 떨어지는 물방울 |
C |
장비침입 방호 |
3 |
∅ 2.5mm의 고체 (기구) 침입 방호 |
수직에서 최대 60°로 떨어지는 물방울 (비) |
D |
전선침입 방호 |
4 |
∅ 1mm의 고체 (전선) 침입 방호 |
(전방향으로) 튀기는 물 |
|
|
5 |
동작에 이상없는 분진침입 방호 |
(전방향으로) 물분출 |
H |
고전압기구 |
6 |
분진침투 없음 |
(전방향으로) 강력한 물분출 |
M |
동작중 물침입에 이상없음 |
7 |
- |
잠시동안 침수 (사용자요구) |
S |
비동작중 물침입에 이상없음 |
8 |
- |
연속적인 잠수 (사용자요구) |
W |
추가된 날씨조건 하에서 사용가능 |
2) NEC : Class I, Division 2, Groups B,C,D
(현재 미주지역에서 사용)
<방폭표기의 의미>
Class I |
Division 2 |
Group B, C, D |
위험물질의 분류 |
위험지역 |
위험물질의 종류 |
① 위험물질의 분류 (CLASS)
분류 |
물질의 종류 |
대표적 적용지역 |
I |
가스, 증기 |
공장, 석유화학공장, 건조지역(dry cleaning), 도색공장, 분무지역(spray area), 석유분배지역(petroleum dispensing), 가스취급시설, 항공기격납고 |
II |
가연성 분진 |
곡물창고, 녹말 취급장소(starch handling), 불꽃 취급장소 (fireworks handling), 밀가루나 사료 제조공장, 분쇄기계, 석탄제조지역(coal preparation), |
III |
점화되기 쉬운 섬유, 털부스러기(flying) |
목재작업지역(wood-working area), 직물제조공장, 조면기(cotton-gin), 목화씨 공장(cotton-seed mill), 아마섬유생산지역(flax production) |
② 위험장소의 분류 (DIVISION)
Division |
1 |
2 |
장 소 |
정상상태시 위험발생장소 |
이상상태시 위험발생장소 |
③ 위험물질의 종류 (GROUP)
Class |
Group |
해 당 물 질 |
I |
A |
아세틸렌 (acetylene) |
B |
수소 |
|
C |
에틸렌 |
|
D |
hexane, propane, benzene, gasoline |
|
II |
E |
금속분진 (aluminum, magnesium 등과 이들의 혼합물) |
F |
carbon black, 석탄(coal) dust, 코크스(coke) dust |
|
G |
밀가루(flour), 녹말(starch), 곡물(grain) dust |
○ NEC와 IEC의 간단한 구분
- Group A : 아세틸렌
Group B : 아세틸렌을 제외한 IIC 해당 가스
Group C : IIB 해당 가스
Group D : IIA 해당 가스
- 단, 분류법이 IEC와 틀리기 때문에 몇몇 가스는 속해있는 그룹이 다름.
3. 위험장소별 방폭구조 적용
장 소 |
본질안전 |
내압 |
압력 |
안전증 |
유입 |
|
ia |
ib |
|||||
0종 장소 |
○ |
- |
- |
- |
- |
- |
1종 장소 |
○ |
○ |
○ |
○ |
△ |
○ |
2종 장소 |
○ |
○ |
○ |
○ |
○ |
○ |
폭연성분진 위험장소 |
특수방진구조 |
|||||
가연성분진 위험장소 |
특수방진구조, 보통방진구조 |
* 안전증방폭구조 : 국내에서는 2종장소에만 적용
(IEC에서는 1종장소에도 적용)
① 위험장소 구분
- 0종장소 : 위험분위기가 정상상태에서 계속해서 발생하거나 또는 발행할 우려가 있는 장소
예) 인화성 액체의 저장용기내 상부공간, 가연성가스용기내부, 가연성액체가 모여있는 Pit Trench 등
- 1종장소 : 위험분위기가 정상상태에서 발생할 우려가 있는 장소
예) 0종장소 주변, 급유구 주변, 운전상 열게되는 연결부주변,
- 2종장소 : 위험분위기가 이상상태(통상적인 유지보수, 고장, 오동작 등)에서 단기간 존재할 수 있는 장소.
예) 1종장소 주변, 설비의 연결부 주변, Pump의 Sealing 주변
☆ 위험장소의 각 기준별 비교
위험분위기 |
정상상태에서 지속적 위험분위기 |
정상상태에서 일시적 위험분위기 |
이상상태에서 위험분위기 |
국내, 일본 |
0종장소 |
1종장소 |
2종장소 |
IEC, 유럽 |
Zone 0 |
Zone 1 |
Zone 2 |
미국 |
Division 1 |
Division 2 |
② 본질안전방폭구조의 종류
- ia : 임의의 2개 고장가정시 점화에대한 안전율을 1.0으로 잡은 것
(안전부품을 3개 사용)
- ib : 정상상태 및 1개의 고장가정시에 안전율을 1.5로 잡은 것.
(안전부품을 2개 사용)
③ 분진의 종류
- 가연성 분진 : 공기중 산소와 발열반응을 일으키고 폭발하는 분진
- 폭연성 분진 : 공기중 산소가 적은 분위기 또는 이산화탄소중에서도 착화하고, 부유상태에서는 심한 폭발을 발생하는 금속분진
<발화도의 구분에따른 온도상승한도와 분진의 종류>
발화도 |
온도상승한도 (℃) |
폭연성분진 |
가연성분진 |
||
과부하 우려없을때 |
과부하 우려있을때 |
도전성 |
비전도성 |
||
11 |
175 |
150 |
마그네슘, 알루미늄, 알루미늄브론즈 |
아연, 코크스, 카본블랙 |
소맥,고무, 염료,페놀수지, 폴리에틸렌 |
12 |
120 |
105 |
알루미늄(수지) |
철, 석탄 |
코코아, 리그닌, 쌀겨 |
13 |
80 |
70 |
|
|
유황 |
4. Engineering Plastic
① Engineering Plastic이란?
- 기존의 방폭기기는 금속제품이 대부분.
- 산업의 발달로 기존 금속을 대신할 수 있는 소재의 개발.
- 장점 : 경량화 (기존금속중량대비 약 70~80%)
내부식성 (내약품성, 내화학성)
가공성 (성형법 : 압축, 압출, 사출.....)
원가절감
② Engineering Plastic 적용제품의 개발
- 방폭제품의 세계적 추세가 금속제품에서 신소재(Engineering Plastic)를 이용하는쪽으로 바뀜.
- 시장 확보
- 기술력 축적
③ 장점
- 경량소형화
- 절연성 우수
- 기능성 우수 (방수성, 기밀성, 내부식성 등)
- 유지보수간편
출처:남북전기교육교재
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