Continuous monitoring of ammonia in a cold storage or freezer room
The food and beverage industry commonly relies on ammonia refrigeration to provide consumers high quality, edible food and drinks. An ammonia leak in a cold storage or freezer room can pose a serious health threat and result in spoiled food and other expensive losses. If a leak is detected, you want the peace of mind that comes with a properly installed ammonia monitoring system.
Using Critical Environment Technologies Canada Inc. (CETCI)’s PDC Multi-Channel Controller and one or more LPT-A Analog Transmitters is the solution. The LPT-A transmitter(s) with an electrochemical ammonia sensor mounted inside the cold storage or freezer room provides continuous monitoring for leaks. The PDC Controller mounted outside the room door provides a status of the air quality conditions inside the room prior to entry.
The PDC Controller has three levels of alarm and the sequence of operation begins with the low alarm which activates the ventilation system. At high alarm, the panel mounted audible alarm as well as any remote alarm devices that are controlled by the high alarm relay will be activated.Typical Cold Storage or Freezer Room Ammonia Monitoring System
Cold storage and freezer rooms vary in size, height and layout. Generally, one fixed LPT-A-NH3 transmitter will provide coverage for approximately 5,000 sq ft. However the arrangement of the shelving units and the amount of food being stored can create walls that segregate areas that cannot be monitored by one transmitter. In this case, multiple LPT-A-NH3 transmitters are recommended to ensure that the health and safety of employees is not jeopardized if an ammonia leak does occur.
Ammonia gas is lighter than air and will accumulate at the highest point in the room. Therefore, the LPT-A-NH3 should be mounted on the ceiling (regardless of how high the ceiling is) away from ventilation fans and any rapidly moving air. The LCD display on the LPT-A-NH3 transmitter can be enabled or disabled, as can the audible alarm. If the temperature of the room is below -20 C (-4 F), an optional heater can be added to the LPT-A-NH3 so the LCD display continues to function in the colder temperatures. When connected to the PDC Controller, the gas measurement readings will be transmitted to the controller and will be viewable on its display.
The PDC Multi-Channel Controller should be mounted outside the cold storage room entry door. It will interface to the LPT-A-NH3 transmitter(s) inside the room and will display the target gas levels for viewing prior to entering the room. The PDC is pre-programmed and completely field adjustable using the board mounted push button keypad. Functions that can be set include relay assignment, time delays, complex zoning, sensor types and ranges, alarm set points, etc. There is a two line backlit LCD display that actively scrolls through all the programmed channels and displays the gas name, concentration and alarm status. The PDC should be configured to set off alarms and activate the exhaust ventilation system or other alarm procedures as appropriate when a leak is detected. The PDC can accept inputs from up to 8 analog transmitters, or 120 digital transmitters using RS-485 digital communication, making it the ideal central controller for any additional gas detection transmitters that may be needed throughout the building.
Remote visual and audible alarm devices such as the Remote Strobe & Horn (RSH-24) should be set up inside the room and outside each entrance to the room.
