Access to Refrigeration Systems
It has long been required that access be considered when designing and installing an ammonia refrigeration system. In fact, we wrote about this topic in some detail back in 2013. However, with the recent release of ANSI/IIAR 2-2014, it is appropriate to revisit all of the relevant access requirements contained within this important RAGAGEP document.
Access to Equipment
ANSI/IIAR 2-2014 §5.12.1 contains the general requirements for accessing equipment:
ANSI/IIAR 2-2014 §5.12.1 General. Equipment shall be accessible for maintenance, as required by the Mechanical Code.
Depending on the model code enforced in your jurisdiction, one of the two codes referenced below would be applicable:
2015 IMC §306.1 Access. Appliances, controls devices, heat exchangers and HVAC system components that utilize energy shall be accessible for inspection, service, repair and replacement without disabling the function of a fire-resistance-rated assembly or removing permanent construction, other appliances, venting systems or any other piping or ducts not connected to the appliance being inspected, serviced, repaired or replaced. A level working space not less than 30 inches deep and 30 inches wide (762 mm by 762 mm) shall be provided in front of the control side to service an appliance.
2015 UMC §304.1 General. Appliances shall be located with respect to building construction and other equipment so as to permit access to the appliance. Sufficient clearance shall be maintained to permit cleaning of heating surfaces; the replacement of filters, blowers, motors, burners, controls, and vent connections; the lubrication of moving parts where necessary; the adjustment and cleaning of burners and pilots; and the proper functioning of explosion vents, where provided. For attic installation, the passageway and servicing area adjacent to the appliance shall be floored. [NFPA 54:9.2.1]
Unless otherwise specified, not less than 30 inches (762 mm) in depth, width, and height of working space shall be provided.
Similarly, ANSI/IIAR 2-2014 §6.3.1 requires equipment in machinery rooms to be accessible and prohibits restriction of emergency egress.
ANSI/IIAR 2-2014 §6.3.1 General. Equipment installed in machinery rooms shall be located in such a manner as to allow egress from any part of the room in the event of an emergency, as required by Section 5.17.7, and to provide clearances required for maintenance, operation, and inspection according to manufacturers’ instructions.
Nine (9) instances requiring service provision to equipment exist within ANSI/IIAR 2-2014:
ANSI/IIAR 2-2014 §7.2.8 Service Provisions. Service provisions shall comply with Section 5.12.
ANSI/IIAR 2-2014 §10.4.4 Shell-and-Tube Condenser Installation Considerations. Where design permits servicing of condenser tubes at its installed location, clearance shall be provided to accommodate maintenance or replacement.
ANSI/IIAR 2-2014 §10.5.4 Plate Heat Exchanger Condenser Installation Considerations. Clearance shall be provided as necessary to accommodate removal and replacement of the condenser plates if this service will be done in the installed location.
ANSI/IIAR 2-2014 §10.6.4 Double-Pipe Condenser Installation Considerations.
ANSI/IIAR 2-2014 §10.6.4.1 Clearance shall be provided as necessary to accommodate removal and replacement of condenser pipes if this service will be done in its installed location.
ANSI/IIAR 2-2014 §220.127.116.11 Installation Considerations [shell and tube evaporators with ammonia in shell]. Installation considerations shall be in accordance with Section 18.104.22.168.
ANSI/IIAR 2-2014 §22.214.171.124 Installation Considerations [shell and tube evaporators with ammonia in tube]. Where design permits servicing of evaporator tubes at their installed location, clearance shall be provided as necessary to accommodate maintenance and replacement.
ANSI/IIAR 2-2014 §11.4.4 Installation Considerations [plate heat exchanger evaporators]. Clearance shall be provided for maintenance or replacement of evaporator plates.
ANSI/IIAR 2-2014 §11.5.4 Installation Considerations [scraped surface heat exchangers]. Clearance shall be provided for the maintenance or replacement of equipment.
ANSI/IIAR 2-2014 §12.6.1 Pressure vessel access shall be provided in accordance with Section 5.12.
Access to Valves
In addition to requiring access to equipment, access to valves is required in four (4) instances:
ANSI/IIAR 2-2014 §126.96.36.199 Manually operated valves that are inaccessible from floor level shall be operable from portable platforms, fixed platforms, ladders, or shall be chain operated.
ANSI/IIAR 2-2014 §188.8.131.52 Manually operated isolation valves identified as being part of the system emergency shutdown procedure shall be directly operable from the floor or chain operated from a permanent work surface. Emergency valve identification shall comply with Section 5.14.3.
ANSI/IIAR 2-2014 §13.3.7 Valves required for system emergency shutdown procedures shall be readily accessible and identified in accordance with Sections 5.14.3 and 184.108.40.206. Other valves shall be accessible in accordance with Section 220.127.116.11 if installed in a machinery room.
ANSI/IIAR 2-2014 §15.2.3 Relief device arrangements shall be configured to allow access for inspection, maintenance, and repair.
While the paragraphs thus far clearly outline the requirements for accessibility, ANSI/IIAR 2-2014 also requires access to be restricted to certain areas:
ANSI/IIAR 2-2014 §6.3.4 Restricted Access. Access to a machinery room shall be restricted to authorized personnel. Signage on machinery room doors shall comply with Section 6.15.
ANSI/IIAR 2-2014 §6.15.3 Restricted Access Signage. Each machinery room entrance door shall be marked with a permanent sign to indicate that only authorized personnel are permitted to enter the room.
ANSI/IIAR 2-2014 §7.2.2 Access [other than machinery rooms]. Access to the refrigeration equipment shall be restricted to authorized personnel.
ANSI/IIAR 2-2014 §16.1.5 Restricted Access to Safety Settings. Changing of safety settings shall be limited to authorized personnel only. Changing of system operational settings shall not permit or affect changes to safety settings.
Designing and installing a safe refrigeration system is not merely an exercise in correctly sizing compressors, condensers, etc. to cool an area. Care must be taken to ensure that equipment and valves are safely accessible for inspection and maintenance. Conversely, access restrictions must be in place to prevent unauthorized persons from making setpoint changes or working in areas that are not intended for normal occupancy.