Refrigeration Plant Safety Overview

Refrigeration systems are designed with varying levels of safety, considering factors like refrigerant leak potential, toxicity, flammability, and occupancy type.

Direct ammonia refrigeration systems can only be used in industrial buildings due to safety concerns.

The machinery room containing ammonia refrigeration equipment must be isolated from the rest of the building with tight construction and doors.

Access to the ammonia machinery room is restricted to authorized personnel only.

Ammonia detectors must be installed in areas where refrigerant leaks could concentrate, triggering an alarm at 300 ppm or less.

No flame-producing devices or hot surfaces above 425°C can be near areas where ammonia leaks may occur.

All ammonia-containing parts, except pipes, low-side components, condensers, and outdoor parts, require installation in a special machinery room.

Systems over 75 kW need to be installed in Class T machinery rooms, which have stricter safety requirements.

Devices that limit the maximum pressure in a refrigeration system by shutting off compressors when a set pressure is reached.

A type of pressure-limiting device that is set to a specific pressure and automatically releases excess pressure to prevent overpressure in a system.

Valves that allow the flow of refrigerant in one direction only, typically used to isolate sections of a refrigeration system.

Systems designed to safely release refrigerant in case of an emergency, such as a leak or overpressure.

The network of pipes that carry refrigerant throughout the refrigeration system.

Instructions provided to operators regarding the safe and efficient operation of the refrigeration system.

The high-pressure side of a refrigeration system, typically where the refrigerant is compressed.

The low-pressure side of a refrigeration system, typically where the refrigerant is expanded and cooled.

Regularly inspecting refrigeration equipment for signs of wear and tear, including vibration, corrosion, damage, blockages and insulation problems.

Testing for leaks in a refrigeration system to ensure refrigerant is not escaping.

Places where leaks commonly occur in refrigeration systems, including valves, valve stem packing, threaded and flanged connections, and flared joints.

Methods used to detect leaks in a refrigeration system, including moist red litmus paper, moist filter paper, sulfur candles and electronic refrigerant sniffers.

A type of leak detector that changes color in the presence of ammonia vapor.

A type of leak detector that produces a white fog when in contact with ammonia vapor.

Checking condensers for leaks at all connections and throughout the coil, including air cooled and water-cooled condensers.

Testing chillers periodically, especially if they use brine, for potential corrosion issues.

A refrigeration system is a high-probability system when there's a risk of refrigerant leaking into occupied spaces due to failed connections, seals, or components. For instance, direct expansion systems, where refrigerant directly cools coils, pose a high leak probability due to potential leakage through HVAC ducts or other means.

Indirect closed or double indirect systems, like chilled water systems used in buildings, are considered low-probability systems. This is because the refrigerant-containing components are isolated from occupied spaces, preventing direct leakage.

Refrigeration systems can be classified based on their operating pressure: High-pressure systems operate with high-side pressures exceeding 100 kPa, while low-pressure systems have high-side pressures below 100 kPa.

Industrial facilities often have restricted access, which reduces risks to the public in case of refrigeration system failures.

Direct expansion systems are a common example of high-probability systems because they use refrigerant directly in cooling coils. If a component fails, refrigerant can easily leak into the occupied space.

Indirect systems, such as chilled water systems, have all refrigerant-containing components separated from the occupied space, reducing the probability of leakage. This isolation is crucial for safety.

Many jurisdictions might not require operators for low-pressure refrigeration plants, which typically have lower risk profiles compared to high-pressure systems.

A refrigeration system's likelihood of leaking refrigerant is determined by its design and components. High-probability systems, like direct expansion systems, have a higher chance of leaking due to direct refrigerant contact. Low-probability systems, featuring isolation, are more secure.

The potential danger a refrigeration system poses, determined by factors like refrigerant type, system size, and location.

R-123, a synthetic refrigerant, is generally considered less toxic than R-717 (ammonia).

Public assembly buildings usually have larger groups of people, making a leak more dangerous as it impacts more individuals.

Systems with a high likelihood of leaks due to age, wear, or design. Requires more frequent inspections.

Systems with a low probability of leaks, typically newer with regular maintenance.

The maximum ammonia concentration level allowed before an alarm activates. Typically set at 25 ppm.

A safety valve that automatically closes if the pressure falls below a certain level, preventing potential hazards.

In case of an ammonia leak, the 'buddy' needs access to water to help flush ammonia from skin or eyes.

The maximum temperature allowed for a hot surface in machinery rooms is 427°C. This limit applies to permanently installed surfaces.

Machinery rooms require ventilation to the outside to ensure fresh air circulation and prevent refrigerant buildup. Mechanical ventilation using fans is usually the preferred method.

Two fan switches are required: one inside the room for convenience and one outside for emergency access. The outside switch can only start the ventilation system, preventing accidental shutdown.

A vapor detector with an alarm should be placed in strategic spots in the room to sense refrigerant leaks. It triggers the ventilation system and signals an alarm when ammonia concentration reaches 300 ppm or less.

The ammonia leak detector panel displays the concentration level, sounds an alarm, and controls various outputs like local/remote alarms and ventilation system activation. It receives data from multiple sensors in the room.

A dedicated shutdown switch is located outside the machinery room for emergency use. This switch allows immediate deactivation of the equipment in case of an emergency.

The shutdown switch for emergency purposes is located outside the machinery room for easy access in dangerous situations or emergency scenarios.

The location of the emergency shutdown switch is carefully chosen for easy access and visibility, allowing quick response in dangerous situations.