《Guidelines for Ammonia Refrigeration Plant Equipment Integrity Programs》(Dec. 6, 2019 )5.7. Open flames and other ignition sources shall be controlled. Open flames and all other sources of ignition are prohibited in the machinery room. Cutting or welding tools, sparking hand tools, portable electric tools (including two-way radios and cell phones) and non-explosion proof electrical equipment are prohibited within the classified electrical areas per CSA B52 section 6.4.2(见Page 20 of 157)