1997 Uniform Mechanical Code^TM

The codes presented below are for Ammonia compressor rooms. Doubl-Kold has extracted the sections that pertain to our industry. This is not a complete and total guide to the codes but only a short and brief compilation.

1106.2   This section pertains to access in and around machinery. (1) An unobstructed walked space at least 3 feet in width and 6 feet 8 inches in height shall be maintained throughout allowing free access to at least two sides of all moving machinery and approaching each stop valve. (2) All access to refrigeration machinery rooms shall be restricted to authorized personnel and posted with a permanent sign.

1106.4   All Machinery rooms shall have approved refrigerant vapor detectors, located in an area where refrigerant from a leak is likely to concentrate, and shall activate visual and audible alarms. Alarms shall be activated at a value not greater than one half the immediately dangerous to life or health (IDLH) or measurement consistent therewith; the PEL, or measurement consistent therewith; or 25 percent of the LFL, whichever is less.

1107.1   Refrigeration machinery rooms shall be provided with a continuous source of outside air for ventilation and removal of rejected heat.

1107.2   Refrigeration machinery rooms shall be provided with dedicated mechanical exhaust systems. The exhaust system shall have the capacity to achieve .05-inch water column gage negative relative to adjacent spaces. This is calculated by the type of structure and its location.

1107.5   Fans providing emergency purge ventilation for refrigerant escape shall have a clearly identified Switch of the break-glass type providing on-only control immediately adjacent to and outside of each refrigerant machinery room exit. Purge fans shall also respond automatically to the refrigerant concentration Detection system set to activate the ventilation system at no more than 25 percent of LFL or 50 percent of the IDLH or a measure equivalent thereto, whichever is less. An emergency purge control shall be provided With a manual reset only.

1107.6   Central control of ventilation system.

1107.7   Ventilation discharge limits from other property and other building opens.

1107.8   Fans to be size and type intended to operate the emergency purge of other than GroupAl or Group B1 refrigerants shall meet the requirements for a Class 1, Division 1 hazardous location as specified in the Elected Code.

1108.4   Emergency Control. A clearly identified switch of the break-glass type providing off-only control of electrically energized equipment and devices within the refrigeration machinery room shall be provided immediately adjacent to and outside of each refrigeration machinery room exit. In addition, emergency shutoff shall also be automatically activated when the concentration of refrigerant vapor exceeds 25 percent of the LFL.

1111.4   Identification of valves. Stop valves shall be identified by tagging in accordance with U.M.C. Standard 11-2. A valve chart shall be mounted under glass at an approved location near the principal Entrance to a refrigeration machinery room.

1121.0   Equipment Identification:

1. A refrigeration system shall be provided with labels complying with this section
   Condensers, Receivers, Absorbers, Accumulator, and all piping.
   In a refrigeration machinery room and for a direct refrigerating system of more than 10 horsepower there Shall be a permanent sign at an approved location giving the following information.
   (A) Name of contractor installing the equipment.
   (B) Name and number designation of refrigerant in system.
   (C) Pounds of refrigerant in system.