Large industrial refrigeration systems often utilize ammonia (NH3) systems to keep the product cold, fresh and safe. The benefits of ammonia refrigeration are undeniable:

• Use of environmentally responsible natural refrigerants.
• Access to a large range of operating temperature (as low as -60°F [-51°C]).
• Higher efficiencies.

Yet, traditional ammonia systems are not one size fits all. These highly engineered systems are erected on-site and become integrated into the building structure. Considering the necessary resources and time constraints involved in constructing these ammonia systems, there exists a need for solutions that offer faster project completion times. In response, some industrial refrigeration system manufacturers have begun collaborating to develop such low charge NH3 system solutions.

By employing compact, direct-weld valves and valve stations, low charge systems reduce leak potential and help lower installation and service costs. With a range of components optimized for a wide pressure range, these systems are designed to combine quality with safe, reliable operation while offering an alternative to traditional large-scale systems.

Typical low charge system installations require multiple parallel low charge systems, ranging from 5 to 60 tons of refrigeration in each, to meet the capacity required for the entire installation. Each system requires a refrigerant charge of 1 to 6 lb of ammonia per ton, comparing favorably to the 20 to 30 lb of ammonia per ton in traditional systems. This charge reduction leads to a need to comply with fewer regulations. Low charge ammonia refrigeration systems can eliminate the need for a process safety management (PSM) program by keeping the total charge below the 10,000-lb threshold.

Along with this charge reduction, off-site consequence analysis, compliance costs and liability also are all lowered. Because each system is independent of one another, the risk of a large refrigerant release is eliminated. In addition, concerns posed to the surrounding community are reduced significantly.

The one-compressor-per-penthouse design eliminates the need to consistently run large compressors at part load. This operating scheme can lower energy consumption and qualify low charge systems for utility rebates. Additionally, frequency drives are standard in most low charge systems, reducing motor speeds under part load. This also helps ensure electricity usage is kept at a minimum.

Typical low charge system installations require multiple parallel low charge systems, ranging from 5 to 60 tons of refrigeration in each, to meet the capacity required for the entire installation.

Low charge systems are shipped with piping prewelded between the compressor package, condenser and valves; therefore, they are ready to be installed with the application of two welds. These systems simplify the complexity of projects even further by operating with one compressor and one condenser, which can be air-cooled on some packages. If the condenser is air-cooled, this eliminates the need for the water supply piping for evaporative condensers often used in site-erected systems.

The installed cost of low charge systems can be competitive with traditional site-erected systems. It can be reduced even further by eliminating water supply piping if air-cooled condensers are included in the low charge system design.

Low charge ammonia systems are a smart alternative to traditional large-scale systems due to their combination of reliability and safety. The fundamental benefits of low charge systems continue to disrupt the landscape of the industrial refrigeration industry while simultaneously minimizing environmental risks due to its independent design.