Determination of explosion reference pressure is important in designing and testing flameproof enclosures (Ex d). Although relative humidity affects to explosion pressure, its effect is not well investigated for the gas group IIB, IIA, and I. This study tested explosion pressure for Ethylene (8 vol.%), Propane (4.6 vol.%), and Methane (9.8 vol.%), which are the representative gas of the gas group IIB, IIA, and I, at ambient temperature and atmospheric pressure (1 atm) under different relative humidity (0% ~ 80%). Ethylene- and Propane-air mixed gases generally tended to decrease as the relative humidity increased; however, explosion pressure was largely dropped at 20% of relative humidity compared to 0% and 10% of relative humidity. On the other hand, Methane-air mixture gas showed similar pressures at 0% and 10% of relative humidity; but no explosion occurred at more than 20%. The results of this study can be used in setting a testing protocol of explosion reference pressure for designing and testing a flameproof enclosure.

Abstract
1. 서 론
2. 실험 방법
    2.1 실험 장치
    2.2 실험 절차
    2.3 통계 분석 방법
3. 실험 결과
    3.1 에틸렌-공기 혼합가스
    3.2 프로판-공기 혼합가스
    3.3 메탄-공기 혼합가스
4. 토의 및 결론
5. References

• 김용태(울산대학교 산업경영공학과) | Yongtae Kim (School of Industrial Engineering, University of Ulsan)
• 정기효(울산대학교 산업경영공학과) | Kihyo Jung (School of Industrial Engineering, University of Ulsan) Corresponding Author