Greenyard Frozen has more than 50 years of experience in providing fresh-frozen fruits and vegetables. At its King’s Lynn production site in the United Kingdom — one of the company’s 10 sites across Europe — Greenyard Frozen needed a robust refrigerant leak detection and notification system. With 20 tons of ammonia on site and a packing capacity of 500 tons of frozen food per day, the British Retail Consortium (BRC)-accredited facility has a freezing capacity of 28 tons per hour or 55,000 tons per annum. The facility includes seven packing lines along with blast freezers and cold storage.

The potential for refrigerant leaks posed a costly problem — not just in cases of slowing production but also for safety compliance. After exploring options, Greenyard selected a multi-zone ammonia leak detection technology that incorporates an online notification platform.

Aspirator sensors are used to detect for ammonia refrigerant leaks in the surrounding air.

Ammonia Safety Compliance

Julie Howlett, the human resources, health, safety and environment director for Greenyard Frozen in the United Kingdom, explains, “Ammonia is extremely toxic at low levels and also has the potential to be explosive given the right conditions. With continuous improvements in the engineering rooms, we wanted to provide low level protection for personnel while also keeping high level protection in accordance with the Dangerous Substances and Explosive Atmospheres regulations.”

Despite having zero global warming potential (GWP) and zero ozone depletion potential (ODP), ammonia (NH3) also is considered a high health hazard because it is corrosive to the skin, eyes and lungs. Ammonia levels of 300 ppm are considered immediately dangerous to life and health, and ammonia is flammable at concentrations of approximately 15 to 28 percent by volume in air.

The team at the King’s Lynn site of Greenyard Frozen prioritized finding a refrigerant management solution that incorporated reliable refrigerant leak detection equipment and refrigerant leak notification.

“[We selected] a complete turnkey package — from the installation of the gas detection equipment through to their connected 24/7/365 online platform to spot trends and set up email alerts,” says Howlett of the system from Bacharach Inc. “It ticked all the boxes in what we were looking for in a detection system.”

The ammonia leak detection unit has a clear LCD display.

Ammonia Leak Detection System

The completed system employs five multi-zone refrigerant monitors capable of refrigerant detection down to 1 ppm. In addition, each refrigeration monitor is able to oversee up to 16 zones through the aspirated system.

 “Traditionally, we had used fixed-point sensors, but with the ongoing costs and maintenance, we looked at different systems,” says Matthew Bilvestone, the cold-store refrigeration engineer at Greenyard Frozen. “The aspirated system came out on top. Maintenance costs are reduced and parts are easier to change, thus reducing callouts.”

The leak detection equipment is shown installed at Greenyard Frozen. The aspirator sensor lines are shown along with the unit for the refrigerant-monitoring software. An additional power unit (located remotely) provides emergency fan operation and backup power supply to ensure safety compliance in the unlikely event that a power cut occurs.

During the selection process, Greenyard Frozen considered the equipment acquisition costs for the aspirated ammonia system vs. a point-sensor solution for the refrigerant monitoring. Additionally, the company factored in the maintenance costs for supporting five aspirated monitors vs. approximately 100 point sensors.

Other features of the aspirated ammonia system influenced Greenyard Frozen as well. For instance, it can be expanded to include up to 48 monitoring zones using spur kit extensions. A high performance pump provides detection distances up to 1,200’ (365 m) from the main unit. A large, graphic LCD display and LED status indicators provide a system-wide overview. The multi-zone system also can provide data-driven functionality when combined with the online refrigerant monitoring platform.

A Bacharach team handled the design and installation of the leak detection equipment at the King’s Lynn facility. It also deployed the refrigerant management software. Knowing where to place sensors when it comes to airflow, refrigerant density and area size are key considerations for early leak detection and safety compliance. In addition, the refrigerant leak detection system had to be installed across the entire site during a short window of time between crop delivery and harvesting.

A schematic highlights the plant room locations at King’s Lynn site of Greenyard Frozen with main refrigerant leak detection equipment. (Click on images for a larger version.)

A leak event graph shows some ammonia being detected at the start of April. The alert setting is at detection levels of 50 ppm at Greenyard Frozen although detection levels can be much lower if required.

Data-Driven Notifications

In addition to the hardware, Greenyard Frozen deployed data-driven refrigerant management software developed by Bacharach. The software provides refrigerant monitoring across the King’s Lynn site from a single point of reference.

Beacon sounders installed in the equipment room are used to notify staff of an ammonia refrigerant leak.

“The web-based software can be looked at from any device, anywhere. With ongoing trends, you can look at past data, set limits and see what areas are causing the most problems, then organize repairs once the leak has been found,” Bilvestone says.

Each sample taken from the hardware is time stamped and stored within a database stored securely in the cloud. Reports can be generated over whatever timeframe is required, providing the ability to review refrigerant leaks across all the appliances to identify problem equipment. For compliance issues, there is an auditable trail of each leak event. It includes the time and date of the event, how much ammonia was detected and how the leak was repaired.

Greenyard Frozen has more than 50 years of experience and provides fresh-frozen, high quality fruits and vegetables. At the King’s Lynn site, pea production takes place mainly in June.

In summary, the complete system has helped Greenyard Frozen continue to provide high quality frozen foods both safely and efficiently. The low maintenance ammonia refrigeration leak-detection system provides greater visibility and understanding as well as a way of managing leak events. “We are now regularly checking for trends and preventing more serious leaks,” says Bilvestone. “Our main project objective was to introduce a low level detection [50 ppm] to alert and protect personnel, which has been achieved.” PC