短语词组短语firedamp emission 沼气泄出firedamp limit 瓦斯极限含量allowable firedamp 容许瓦斯气量firedamp layer [矿业]瓦斯积聚层;瓦斯层firedamp pool 沼气池firedamp alarm 沼气警报firedamp indicator 沼气检定器;瓦斯指示器firedamp accumulation 瓦斯积聚firedamp migration [矿业]瓦斯迁移 返回 firedamp