IIAR

By Jeffrey M. Shapiro, PE., FSFPE

Every three years, new editions of the International and Uniform codes are published and made available for adoption by state and local jurisdictions. The most recent editions of these codes, dated 2009, incorporate more than a thousand changes when compared to the 2006 editions. Most of these changes are specifically identified in the code by vertical “bars” in the margins, which indicate new or revised text, or arrows in the margin, which indicate deleted text

Because of the time and effort required by jurisdictions to review new code editions prior to adoption, most jurisdictions take a year or more to update their codes (many take far longer or entirely skip some code editions). So, now that a year has passed since the 2009 codes were published, we’re beginning to see enactment of these codes.

Changes affecting the ammonia refrigeration industry in the new codes generally have a positive impact and will help us do a better job of ensuring safe installations of ammonia refrigeration equipment. To assist IIAR members in becoming more familiar with new and revised regulations, I’ve prepared a summary of the major revisions that you’ll see as you go through the 2009 edition. Note that some of the information below has been duplicated where multiple codes had similar changes so that readers can quickly evaluate significant changes to each code in their entirety rather than having to cross-reference back and forth among the codes.

International Fire Code

Section 606.8 Refrigerant Detectors: This section was revised to require that refrigerant detectors, when activated, transmit an alerting signal to an “approved” location. The term “approved” refers to whatever the local authority will accept as a reasonable basis of system monitoring. In some cases, this might be a central station service monitoring other alarm signals for the same facility. In other cases, it may make the most sense to have the approved location be a pager carried by the on-duty refrigeration engineer responsible for the facility.

Section 606.9.1 Refrigeration System Emergency Shutoff: The requirement for an emergency shutoff switch for machinery rooms has been revised in three ways. First, the previous mandate requiring the switch be mounted in a “break glass” enclosure has been changed to allow any tamper-resistant cover that is satisfactory to local authorities.

Second, equipment required to be controlled by the emergency shutoff switch has been clarified. Previously, the code implied that all electrical equipment and devices in the machinery room had to be stopped by the switch, and some jurisdictions interpreted the provision as even requiring shutoff of convenience outlets. The code is now specific in only requiring shutoff of refrigerant compressors, refrigerant pumps and normallyclosed automatic refrigerant valves. It is recognized that some owners and designers prefer a complete electrical shunt for machinery rooms in the event of a significant leak, as opposed to what the code now requires. This type of design remains an option for those who chose it, but it’s no longer the code mandated minimum.

The third revision to Section 606.9.1 is a new requirement for the shutoff control to be integrated with refrigerant leak detectors located in the machinery room. The detection system, upon sensing a leak event with a concentration reaching 25 percent of the lower flammable limit for the refrigerant or reaching the upper detection limit for the detector (whichever is lower), must now automatically trigger the emergency shutoff, as described above.

Sections 606.10.1.1 and 606.10.2.2 Overpressure Limit Setpoint: The buffer between the pressure relief valve rated operating pressure and the emergency pressure control system’s operating pressure has been revised from 15 psi to 10% of the PRV rated operating pressure. This provides a greater factor of safety to prevent weeping of a PRV in an overpressure condition before the EPCS operates.

Section 606.13 Discharge Location for Refrigeration Machinery Room Ventilation: The previous requirement for room exhaust from ammonia machinery rooms to be routed through a treatment system before release to atmosphere has been deleted.

International Mechanical Code

Section 1101.10 Locking Access Port Caps: A requirement has been added to have all refrigerant access ports located outdoors to be equipped with locking, tamper-resistant caps. This provision was not targeted at industrial refrigeration systems, but the way the code change proposal was worded didn’t exclude these types of facilities. This change was made at the last code hearing of the 2009 cycle, which did not allow time for any “fixes” to be made to address concerns. However, in the current code cycle, which will ultimately impact the 2012 IMC, IIAR was successful in getting a revision to this section approved that permits “other means” of ensuring that access ports are protected from unauthorized access.

Section 1104.2.2(6) Industrial Occupancies and Refrigerated Rooms: The requirement to use classified (hazardous) location electrical equipment in process and storage areas where ammonia refrigeration is provided was deleted. This change makes the IMC consistent with requirements of ASHRAE 15.

Uniform Mechanical Code

Section 1102.0 General: ASHRAE 15 and IIAR 2 are now referenced as mandatory standards, applying in full except where the UMC specifies a differing requirement, in which case, the UMC prevails.

Section 1105.3.3 Refrigerated Process and Storage Areas: The requirement for ammonia process and storage areas to be classified as Class I, Division 1 hazardous electrical locations, in accordance with the electrical code, has been revised to exclude areas using ammonia as a refrigerant. This change makes the UMC consistent with all other codes that deal with this topic. Also, the requirement for refrigerant detection in process and storage areas to activate automatic valves to stop the flow of refrigerant out of the machine room and stop the flow of refrigerant to evaporators that previously appeared in Section 1121.1 was eliminated when that section was consolidated, in part, with this one.

Section 1108.5 Emergency Control of the Ventilation Systems: The ammonia concentration set point for initiating emergency ventilation has been increased from 150 ppm to 1,000 ppm, which reduces the possibility of unnecessarily triggering emergency ventilation in the event of a small fugitive release, which might occur during routine oil draining or other system service work. Although accidentally activating emergency ventilation might not typically cause a problem, there are cases, such as extremely cold climates, where introducing large volumes of unconditioned air into the machinery room could cause problems.

Section 1108.7 Ventilation Discharge: The previous requirement for room exhaust from ammonia machinery rooms to be routed through a treatment system before release to atmosphere has been deleted.

Section 1120 Ammonia Discharge: The previous requirement for emergency diffusion tanks to be designed on a basis of one gallon of water per pound of ammonia, calculated using the entire system charge, has been reduced. The volume of water required in diffusion tanks is now limited to that required to handle a one-hour discharge from the single largest relief device on the system, still using the one gallon of water per pound of ammonia ratio.

Section 1121.1 Detection and Alarm Systems: Some of the provisions previously located in this section were relocated to Section 1105.3.3. See discussion of that section above.

Section 1122 Emergency Pressure Control System: The requirement to provide an emergency pressure control system for ammonia refrigeration, previously added to the International codes, was added to the UMC for consistency. Those involved in codes over the past few years will recall that the emergency pressure control system was added to codes as a basis for justifying elimination of the archaic requirement for manual emergency control boxes.

Uniform Fire Code

Sections 53.2.1.1.1 and 53.2.1.2.1 Overpressure Limit Setpoint: The buffer between the pressure relief valve rated operating pressure and the emergency pressure control system’s operating pressure has been revised from 15 psi to 10% of the PRV rated operating pressure. This provides a greater factor of safety to prevent weeping of a PRV in an overpressure condition before the EPCS operates

Section 53.2.3.1.6 Refrigerant Detector Monitoring and Annunciation: This section was revised to require that refrigerant detectors, when activated, transmit an alerting signal to an “approved” location. The term “approved” refers to whatever the local authority will accept as a reasonable basis of system monitoring. In some cases, this might be a central station service monitoring other alarm signals for the same facility. In other cases, it may make the most sense to have the approved location be a pager carried by the on-duty refrigeration engineer responsible for the facility.

Section 53.2.3.4.5 Refrigeration System Emergency Shutoff: The requirement for an emergency shutoff switch for machinery rooms has been revised in three ways. First, the previous mandate requiring the switch be mounted in a “break glass” enclosure has been changed to allow any tamperresistant cover that is satisfactory to local authorities. Second, equipment required to be controlled by the emergency shutoff switch has been clarified. Previously, the code implied that all electrical equipment and devices in the machinery room had to be stopped by the switch, and some jurisdictions interpreted the provision as even requiring shutoff of convenience outlets. The code is now specific in only requiring shutoff of refrigerant compressors, refrigerant pumps and normally-closed automatic refrigeration valves. It is recognized that some owners and designers prefer a complete electrical shunt for machinery rooms in the event of a significant leak, as opposed to what the code now requires. This type of design remains an option for those who chose it, but it’s no longer the code mandated minimum.

Third, there is a new requirement for the shutoff control to be integrated with refrigerant leak detectors located in the machinery room. The detection system, upon sensing a leak event with a concentration reaching 25 percent of the lower flammable limit for the refrigerant or reaching the upper detection limit for the detector (whichever is lower), must now automatically trigger the emergency shutoff, as described above.

Section 53.2.3.3.13.2 Ventilation Discharge: The previous requirement for room exhaust from ammonia machinery rooms to be routed through a treatment system before release to atmosphere has been deleted.

More details on individual changes in the International codes can be found in “Code Change Resource Collections” books published by ICC. These books include the complete history of each change made to the 2009 codes.

IIAR continues to work on the model codes to ensure that they specify reasonable, appropriate and consistent regulations and coordinate with ASHRAE 15 and IIAR 2 to the greatest extent possible. Look for an update on proposals to the 2012 codes in an upcoming column.