What? I didn’t know that


I recently read an article about a man that spent a considerLESSON able amount of time tromping through the wilderness back in the early 1900s. In his journa he made a statement that I found interesting. He wrote, “I don’t know where I am, but it doesn’t matter.” I am concerned when someone doesn’t know where they are or what is going on, and they think it “doesn’t matter.” I think it can matter a lot where you are, and what you know when you are there. On this man’s last trip in the wilderness it certainly did matter to him. He was found some weeks later after drowning in a river. This man’s statement got me thinking about something I have run into numerous times, where people don’t know something and they also don’t realize it really does matter.

If you are in the design and construction field of industrial ammonia refrigeration, you have probably experienced this. You design most, if not all, of the ammonia refrigeration system. You properly size equipment for the intended load(s), properly size and configure piping, correctly select control valves as well as hand valves, properly size vessels, etc. You do everything needed for the ammonia system to function correctly. However, there are some items and work associated with the ammonia system that you may not do, but you are aware of what is required. Those items and that work may be done by a General Contractor, or some other contractor or sub-contractor. If the items are not done correctly the facility owner, who is relying on more knowledgeable people to do the right thing, may have serious challenges. The “Authority having Jurisdiction” may not agree with what was or wasn’t done, and require corrective action. Or at a later date, OSHA and/ or EPA may site the missing items for corrective action, along with a fine.

The issues involve the ammonia machine room, and what should be part of the machine room design. I have run into this many times over several decades of design and construction, and I experienced this same issue again just recently when a knowledgeable refrigeration operator asked me what should be included in the machine room design.

For industrial ammonia refrigeration the standard for safe design is ANSI/IIAR 2-2014 Addendum A (2019). I have been surprised time and again at how many people do not know about some of the key safe design standards in this document. Here are some of those key safety items that we should all know and understand:

  •  Ammonia detection and alarming. Almost everyone, but not all, realize there should be ammonia detection in the machine room. Beyond that, understanding of what should be in place gets fuzzy. ANSI/IIAR 2 2014 Addendum A, paragraph 6.13.1 states:

    6.13.1 General. Machinery rooms shall be provided with ammonia detection and alarm in accordance with Sections 17.2–17.6 and the following features:

    1. At least one ammonia detector shall be provided in the room or area.
    2. The detector shall activate an alarm that reports to a monitored location so that corrective action can be taken at an indicated concentration of 25 ppm or higher 
    3.   Audible and visual alarms shall be provided inside the room to warn that access to the room is restricted to authorized personnel and emergency responders when the alarm has activated. Additional audible and visual alarms shall be located outside of each entrance to the machinery room.

    I am guessing that many do not read, or have access to the information stated in, which states that “… audible and visual alarms shall be located outside of each entrance to the machinery room.”

  • Next, I think that most of the people involved in the design and construction of ammonia refrigeration machine rooms understand that there should be a ventilation system in that room, and that an ammonia detector should activate the emergency ventilation system. Beyond this, it seems knowledge and understanding are lacking, and it is not generally understood that there is more to be done. Paragraph 6.13.4 states:

    “Detection of ammonia concentrations that exceed a detector’s upper detection limit or 40,000 ppm (25% LFL), whichever is lower, shall activate visual indicators and an audible alarm and shall activate emergency ventilation, where required, in accordance with Section 6.14.7. Once activated, emergency ventilation shall continue to operate until being manually reset by a switch located in the machinery room. In addition, the following equipment in the machinery room shall be automatically de-energized:

    1. Refrigerant compressors
    2. Refrigerant pumps, and
    3. Normally closed automatic refrigerant valves that are not part of an emergency control system.”

    Many ammonia machine rooms may have this high-level detection. Some may shut compressors down on activation of the high-level PPM. More rare are systems that shutdown other equipment and controls in the machine room.

  • Most machine room designs include “Emergency Control Switches”, but what that switch does can vary considerably from one facility to another. It is common that the switch shuts down the compressors, but often that’s all. As stated in paragraph 6.12.1 that switch should do the following:
    “The switch shall provide off-only control of refrigerant compressors, refrigerant pumps, and normally closed automatic refrigerant valves that are not part of an emergency control system, located in the machinery room. The function of the switch shall be clearly marked by signage near the controls.”
  • Construction of ammonia machine rooms sometimes lacks what is stated in Chapter 6. The following are a few key paragraphs:

    6.2.1 Separation and Fire Protection. The machinery room shall be separated from the remainder of the building by tight-fitting construction having a onehour fire-resistance rating. Doors shall comply with Section 6.10.

    6.10.2 Door Features. Machinery room doors shall be self-closing and tight fitting. Doors that are part of the means of egress shall be equipped with panic hardware and shall be side hinged to swing in the direction of egress for occupants leaving the machinery room. Where the machinery room is not provided with fire sprinklers, doors communicating with the building interior shall be one-hour fire-rated. Doors to the outdoors shall be fire rated where required by the Building Code based on the fire rating required for exterior wall openings.

    To help in understanding of what constitutes a tight-fitting door there is a definition in ANSI/IIAR 1-2017 Definitions and Terminology Used in IIAR Standards.

    “tight-fitting door: A tightly constructed door with seals to minimize gap clearances between the entire door perimeter and its fixed door frame that is intended to control the transfer of liquid, moisture, air, and vapor.”

    A large percentage of machine rooms do not have tight-fitting doors. Many could easily accommodate a mouse, and I am sure ammonia molecules would have no problem escaping.

    Similar to the doors, numerous machine rooms do not properly address the penetrations through the machine room envelope, as they should as stated in the following paragraph:

    6.6.2 Pipe Penetrations. Pipes penetrating the machinery room separation shall be sealed to the walls, ceiling, or floor through which they pass in accordance with Section 6.2.1. Where Section 6.2.1 requires that the separation have a fire rating, pipe penetrations shall be fire stopped in accordance with the Building Code.

There are several other key features that should be part of a properly constructed ammonia refrigeration machine room in Chapter 6 of ANSI/IIAR 2 2014 Addendum A. As an ammonia refrigeration designer, engineer, contractor, operator, etc. each should study and understand what is included in this ANSI/IIAR Standard. And, you should pass your understanding along to those who may not know.

If you don’t know does it matter? Yes it does.

The IIAR-2 Academy of Natural Refrigerants certificate course provides a comprehensive review of the standard. The course is offered online to provide easy access to match anyone’s schedule.