With today’s announcement of the OSHRC decision that the IMC was the facilities RAGAGEP and that the IMC does not require detectors, I thought this record needs to be CORRECTED and CLARIFIED, as the ALJ’s understanding of how the IMC and its requirements apply to an ammonia refrigeration process/system. In the decision, the facility successfully argued that their stated RAGAGEP, ASHRAE 15, is overruled by the International Mechanical Code (IMC) and that the IMC (no year stated) does not require ammonia detectors inside the engine room/mechanical room. Here we go….
The IMC, SECTION 1105 MACHINERY ROOM, GENERAL REQUIREMENTS states:
1105.1 Design and construction.
Machinery rooms shall be designed and constructed in accordance with the International Building Code and this section.
…
1105.3 Refrigerant detector.
Refrigerant detectors in machinery rooms shall be provided as required by Section 606.8 of the International Fire Code.
As we look at Section 606.8 of the International Fire Code, we see the following:
606.8 Refrigerant detector.
Machinery rooms shall contain a refrigerant detector with an audible and visual alarm. The detector, or a sampling tube that draws air to the detector, shall be located in an area where refrigerant from a leak will concentrate. The alarm shall be actuated at a value not greater than the corresponding TLV-TWA values shown in the International Mechanical Code for the refrigerant classification. Detectors and alarms shall be placed in approved locations. The detector shall transmit a signal to an approved location.
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NOTE: in the 2018 IFC, this is 605.8 and it reads like this… 605.8 Refrigerant detection. Machinery rooms shall be provided with a refrigerant detector with an audible and visible alarm. Where ammonia is used as the refrigerant, detection shall comply with IIAR 2. For refrigerants other than ammonia, refrigerant detection shall comply with Section 605.8.1 605.8.1 Refrigerants other than ammonia. A detector, or a sampling tube that draws air to a detector, shall be provided at an approved location where refrigerant from a leak is expected to accumulate. The system shall be designed to initiate audible and visible alarms inside of and outside each entrance to the refrigerating machinery room and transmit a signal to an approved location where the concentration of refrigerant detected exceeds the lesser of the following: 1.The corresponding TLV-TWA values shown in the International Mechanical Code for the refrigerant classification. 2.Twenty-five percent of the lower flammable limit (LFL). Detection of a refrigerant concentration exceeding the upper detection limit or 25 percent of the lower flammable limit (LFL), whichever is lower, shall stop refrigerant equipment in the machinery room in accordance with Section 605.9.1. |
The ALJ was mislead to believe that if the engine room/mechanical room was “continuously ventilated” then detection was not a requirement and he referred to the following section of the IMC, SECTION 1106 MACHINERY ROOM, SPECIAL REQUIREMENTS; which by the way is an entirely different section of the code and in NOW WAY negates Section 1105, Machinery Room, General Requirements.
1106.3 Ammonia room ventilation.
Ventilation systems in ammonia machinery rooms shall be operated continuously at the ventilation rate specified in Section 1105.6.3.
Exceptions:
1. Machinery rooms equipped with a vapor detector that will automatically start the ventilation system at the ventilation rate specified in Section 1105.6.3, and that will actuate an alarm at a detection level not to exceed 1,000 ppm.
2. Machinery rooms conforming to the Class 1, Division 2, hazardous location classification requirements of NFPA 70.
The IMC offers the following “commentary” in relation to the requirement(s) in 1105.3 Refrigerant detector. (emphasis by me, but the words of the IMC)
A refrigerant-specific detector is REQUIRED for leak detection, early warning, and actuation of emergency exhaust systems. Detector requirements are found in Section 606 of the IFC. Depending on the density of the refrigerants, leakage may collect near the floor, near the ceiling or disperse equally throughout the space. Refrigerant detector locations must be carefully considered. Most refrigerants are heavier than air, making floor depressions and pits natural areas for accumulation. The code does not specify the location of sensors because of the endless variety of equipment room designs. The key to properly locating a detector in the machinery room is to remember that occupant safety is the primary objective, and the danger is in breathing refrigerant. Placing the sensor below the common breathing height of 5 feet (1525 mm) results in an additional safety margin because all commonly used halocarbon refrigerants are three to five times heavier than air. When undistributed by airflow, escaping refrigerant will flow to the floor, seeking the lowest levels and filling the room from the bottom up. Because pits, stairwells or trenches are likely to fill with refrigerant first, detectors should also be placed in any of these areas that may be occupied. The alarm actuation threshold is dictated by the last column of Table 1103.1. Manufacturers’ instructions for detectors will provide installation guidance for the location of detectors and the required number of detectors for any given room size.
Because most general machinery rooms are unoccupied for long periods, a refrigeration leak may go undetected, allowing a buildup of refrigerant that can pose a threat to the building occupants and the maintenance personnel who will be required to enter the machinery room. Also, the refrigerants may or may not be detectable by the senses of smell, sight and taste, depending on the chemical nature and concentration of the refrigerant in air. This can be especially critical when a toxic refrigerant is used in the refrigeration system.
The ACGIH defines three levels of refrigerant exposure: Level 1 is the AEL, which is the level at which a person can be exposed for 8 hours per day for 40 hours per week without having an adverse effect on health. Level 2 is the STEL, which is defined as three times the AEL. At this level a person should not be exposed for more than 30 minutes at a time. Persons working in a machinery room having this concentration of refrigerant should be equipped with respiratory protection. Level 3 is the emergency exposure limit (EEL). At this level, persons should not be in the room at all without a self-contained breathing apparatus.
Early detection of leaking refrigerant depends on the location of the refrigerant detectors. If they are improperly located, a refrigerant leak could go undetected for an undesirable length of time, thus allowing a significant amount of refrigerant to escape. Items to be considered when choosing locations for detectors are the airflow patterns of the room, the particular refrigerant density and the fact that the primary hazard to the occupants is inhalation. The detectors should be located to prevent the normal ventilation system from interfering with detection. Placing detectors between the refrigeration system and exhaust fan inlets should help to ensure that the presence of refrigerant will be detected. Depending on the size of the machinery room and the number and type of refrigeration systems, more than one detector may be necessary. Manufacturers’ installation instructions for the refrigeration detection system should be followed when choosing the location and the number of sensors for a particular machinery room application. For example, many refrigerant detection systems are capable of activating a warning system with a warning light, alarm or similar device if refrigerant exceeds a preset concentration or level due to a leak. Typically, the warning systems have the capability to alert people inside and outside the machinery room so that the leak can be quickly located and repaired.
The code commentary for IFC 606.8 Refrigerant detector, states:
Section 1105.3 of the IMC refers to the code for refrigerant detector requirements. Refrigerant detectors provide early warning of refrigerant leakage. Such leakage could result in a significant fire or health hazard if not discovered and stopped or if occupants are not evacuated from the building. Machinery rooms are required by the IMC where refrigerant quantities exceed specified limits. Detector location is critical to early leakage warning and should comply with the detector manufacturer’s instructions. THE REQUIRED DETECTORS must be designed for application with the refrigerant or refrigerants used in the machinery room. Because machinery rooms are unattended most of the time, once the refrigerant gas is detected at the levels noted in this section, a local alarm must be initiated and a signal must be transmitted to an approved location remote from the machinery room, such as a security room or fire command center, or possibly to an on-duty, onsite technician via pager or cell phone. The alarm is intended to alert those both inside the area of detection and in the immediate vicinity to prevent harm to those outside the area of refrigerant gas release. The notification to an approved location provides timely information to those who must take a role in emergency response, whereas the local alarm is a warning for those in the vicinity of the release. As a first step in the mitigation of the hazards of fugitive refrigerant gas, the required detectors have the additional important role of activating the emergency ventilation/exhaust systems in the machinery rooms required by Sections 1105.6.3 and 1106.3 of the IMC (see the definition of “Machinery room” and Table 1103.1, both in the IMC).
Some may be wondering what “code commentary” is. Here is how the ICC explains it:
The principal purpose of this Commentary is to provide a basic volume of knowledge and facts relating to the code. The Commentary provides it in a small package and at reasonable cost thorough coverage of many issues likely to be dealt with when using the International Mechanical Code—and then supplements that coverage with historical and technical background.
Safety Tip for process safety practitioners and engineers: NEVER buy the code alone; ALWAYS buy the code with commentary! You can learn so much about the application of the code requirements from none other than the code authors!
So does ASHRAE 15 exemption the requirement for detectors? Here is what the ALJ stated:
[ASHRAE 15] Section 8.11.2.1 provides for an exception, which indicates
“[f]or ammonia, refer to 8.12(g).”
[SAFTENG NOTE: This may have been correct in a previous edition, but in the 2010 revision, this exception refers to 8.12(h), not (g)]
Since the refrigerating machinery room at issue used ammonia, the Secretary’s reliance on Section 8.11.2.1 is misplaced. Rather, the Secretary was required to refer to Section 8.12(g) to determine compliance, which provides that
“[w]hen refrigerants of Groups A2, A3, B2, and B3 are used, the machinery room shall conform to Class 1, Division 2, of the National Electrical Code.”
Ammonia falls into Group B2, and therefore, unless another exception applies, the facility’ machinery room was required to conform to Class 1, Division 2, of the National Electrical Code.
However, another exception does apply. Section 8.12(g)’s exception indicates
“[w]hen ammonia is used, the requirements of Class 1, Division 2, of the National Electrical Code shall not apply providing the requirements of 8.12(h) are met.”
Therefore, the facility’ machinery room was not required to conform to Class 1, Division 2, of the National Electrical Code if it met the requirements of Section 8.12(h).
Section 8.12(h) mandates
“[w]hen ammonia is used, the machinery room is not required to meet Class 1, Division 2, of the National Electrical Code providing
(1) the mechanical ventilation system in the machinery room is run continuously and failure of the mechanical ventilation system actuates an alarm or
(2) the machinery room is equipped with a detector, conforming to 8.11.2.1, except the detector shall alarm at 1,000 ppm.” (Id.)
It is undisputed that the facility runs the mechanical ventilation system in the machinery room continuously. The parties also stipulated “were the ventilation system in the machinery room to fail, a visual-only alarm would trigger in the control room.” Therefore, the facility contends it has met the series of exceptions to sections 8.11.2.1 and 8.12 and is not required to have ammonia detectors in its machinery room.
This entire argument/discussion does NOT make the argument that NH3 detection is exempt!! See my explanation below.
In full disclosure, here is what ASHRAE 15, 2010 states: [SAFTENG NOTE: the process was built in 2006 and may have been using an earlier version of ASHRAE 15]
8.11 Refrigerating Machinery Room, General Requirements.
When a refrigerating system is located indoors and a machinery room is required by Section 7.4, the machinery room shall be in accordance with the following provisions.
8.11.1 Machinery rooms are not prohibited from housing other mechanical equipment unless specifically prohibited elsewhere in this standard. A machinery room shall be so dimensioned that parts are accessible with space for service, maintenance, and operations. There shall be clear head room of not less than 7.25 ft (2.2 m) below equipment situated over passageways.
8.11.2 Each refrigerating machinery room shall have a tightfitting door or doors opening outward, self-closing if they open into the building and adequate in number to ensure freedom for persons to escape in an emergency. With the exception of access doors and panels in air ducts and air-handling units conforming to Section 8.11.7, there shall be no openings that will permit passage of escaping refrigerant to other parts of the building.
8.11.2.1 Each refrigerating machinery room shall contain a detector, located in an area where refrigerant from a leak will concentrate, that actuates an alarm and mechanical ventilation in accordance with Section 8.11.4 at a value not greater than the corresponding TLV-TWA (or toxicity measure consistent therewith). The alarm shall annunciate visual and audible alarms inside the refrigerating machinery room and outside each entrance to the refrigerating machinery room. The alarms required in this section shall be of the manual reset type with the reset located inside the refrigerating machinery room. Alarms set at other levels (such as IDLH) and automatic reset alarms are permitted in addition to those required by this section. The meaning of each alarm shall be clearly marked by signage near the annunciators.
Exceptions:
a. For ammonia, refer to Section 8.12(h).
b. Detectors are not required when only systems using R-718 (water) are located in the refrigerating machinery room.
8.12 Machinery Room, Special Requirements. In cases specified in the rules of Section 7.4, a refrigerating machinery room shall meet the following special requirements in addition to those in Section 8.11:
a. There shall be no flame-producing device or continuously operating hot surface over 800°F (427°C) permanently installed in the room.
b. Doors communicating with the building shall be approved, self-closing, tight-fitting fire doors.
c. Walls, floor, and ceiling shall be tight and of noncombustible construction. Walls, floor, and ceiling separating the refrigerating machinery room from other occupied spaces shall be of at least one-hour fire-resistive construction.
d. The refrigerating machinery room shall have a door that opens directly to the outdoors or through a vestibule equipped with self-closing, tight-fitting doors.
e. Exterior openings, if present, shall not be under any fire escape or any open stairway.
f. All pipes piercing the interior walls, ceiling, or floor of such rooms shall be tightly sealed to the walls, ceiling, or floor through which they pass.
g. When refrigerants of Groups A2, A3, B2, and B3 are used, the machinery room shall conform to Class 1, Division 2, of the National Electrical Code. When refrigerant Groups A 1 and Blare used, the machinery room is not required to meet Class 1, Division 2, of the National Electrical Code.
Exception: When ammonia is used, the requirements of Class 1, Division 2, of the National Electrical Code shall not apply providing the requirements of Section 8.12(h) are met.
h. When ammonia (R-717) is used, the machinery room is not required to meet Class 1, Division 2, of the National Electrical Code, providing (1) the mechanical ventilation system in the machinery room is run continuously and failure of the mechanical ventilation system actuates an alarm or (2) the machinery room is equipped with a detector, conforming to Section 8.11.2.1, except the detector shall alarm at 1000 ppm.
i. Remote control of the mechanical equipment in the refrigerating machinery room shall be provided immediately outside the machinery room door solely for the purpose of shutting down the equipment in an emergency. Ventilation fans shall be on a separate electrical circuit and have a control switch located immediately outside the machinery room door.
So what exactly is line item “h” above requiring?
This EXCEPTION is based on the NFPA 70 exception for ammonia engine rooms. If the designer/operator/owner/employer does NOT want to make their ammonia engine rooms a Class I, Div 2 HAZLOC they have two (2) options:
- the mechanical ventilation system in the machinery room is run continuously and failure of the mechanical ventilation system actuates an alarm, OR
- the machinery room is equipped with a detector, conforming to Section 8.11.2.1, except the detector shall alarm at 1000 ppm
So what ventilation are they referring to in #1 above? As many recognize, there are two (2) distinct ventilation requirements for ammonia engine rooms:
- to protect equipment from overheating and
- to ensure the ammonia concentration never exceeds 25% of it’s LEL (e.g. 40,000 ppm).
The exception #1 above, that exempts the room from being a HAZLOC, is referring to the ventilation system that ensures a leak of ammonia would never exceed 40,000 ppm. A lot of folks call this mode of ventilation – “emergency ventilation” and if the designer/operator/owner/employer wants to run their engine room under the CFM flow at ALL TIMES then the engine room need NOT be managed as a HAZLOC nor would it need detectors, since the room is CONTINUOUSLY VENTILATED as if there is a leak. What the ALJ failed to understand, was the significant difference in these ventilation flow rates. I can not recall ever being inside an engine room that had their “emergency ventilation” run continuously; the fans to remove the heat from the room – yes; the big boy fans that can lift your hard-hat off your head (that’s a pun) never. Had OSHA been able to explain these differences and the judge asked a few clarifying questions this citation may have been held up. But let’s be clear, ASHRAE 15 REQUIRES NH3 Detectors when the room ventilation does not meet section 8.11.5.