This document is an instruction manual for Fuji Electric's cross-stack laser gas analyzer (Type: ZSS). The document includes information on the installation, operation, and maintenance of the gas analyzer. Users are advised to carefully read this manual to avoid accidents or failures due to improper handling. The manual also states that any modification of the gas analyzer without written approval from the manufacturer is strictly prohibited. If modification is necessary, users should contact the manufacturer in advance. The manufacturer is Fuji Electric Instrumentation Co., Ltd.