The ammonia refrigeration industry has always had a strong commitment to safety, including concern for the health and welfare of those who work at ammonia refrigeration facilities as well as the neighbors who live nearby. That commitment includes paying attention to site security.
In the past few years, security at ammonia refrigeration facilities has received more attention because of reported thefts of ammonia. Fertilizer tanks have become a common target for criminals who steal ammonia for the manufacture of illegal methamphetamine. However, some thefts also have occurred at refrigeration facilities. While I think our industry is well prepared to meet the enhanced levels of security required of all industrial facilities since September 11, it is still a good idea to review your security practices.
Many ammonia refrigeration facilities prevent unauthorized access to critical equipment by using security fences, door locks, windowless walls and alarm systems. Surveillance videos, security guards and metal/explosive detection systems also are used to identify intruders. Many companies require badges, security clearance and vehicle passes to control access to their facilities. Most companies maintain close control of keys to the facility and often change locks when a disgruntled employee leaves.
When receivers or other major system components that contain ammonia are located outdoors, they could be damaged by trucks, forklifts or construction vehicles. In these situations, collision barriers should be installed, and it is always a good idea to "over-design" these barriers. It's also a good idea to plug all vent and drain valves tightly or to secure them with locks or caps. All level indicators such as sight glasses should have ball check valves installed in case the indicator is damaged.
Some facilities employ a "nurse tank" of ammonia to replenish the plant charge. Often, these tanks are connected directly to the refrigeration system by a hose. A good practice might be to include a check valve at the system connection. Because the hose can be susceptible to damage or failure, an even better practice is to disconnect the tank and remove it from the area after restoring the system's full charge. If a hose must be used, breakaway couplings are good safety devices to employ because they limit potential release quantities to the content of the hose.
Safety codes such as IIAR-2 and ASHRAE-15 require ammonia detectors in machinery rooms to provide an alert in the event of an ammonia leak. Facilities that are operated by remote control should have monitoring systems that alert local emergency responders as well as plant safety personnel in the event of a release. Owners of remotely operated facilities may want to consider installing burglar alarms or other security devices to detect unauthorized visitors and intruders.
Having a good process safety management (PSM) program in place enhances the operations safety of an ammonia refrigeration system. In addition to the detailed operating procedures outlined in a facility's PSM program -- for example, proper plant shutdown and emergency contingency plans -- site security of the system should be addressed as an element of the hazard analysis review. Here's a list of questions you might want to review with your local authorities:
- Are walls, fences, locked gates or guards adequate to protect your facility?
- Are windows easily accessible?
- How big is the system charge?
- What is the total amount of ammonia located on site?
- Is any equipment unprotected?
- What are the plant's hours of operation?
- Is your plant located near densely populated areas?
- Is your site or refrigeration system accessible by unauthorized intruders?
- How many shifts does the facility run?
- Who has access to the ammonia machinery room?
As always, the objective of site security provisions is to prevent releases of ammonia that might affect employees or the general public. In addition, the provisions protect against a disruption of business. And, they'll make you a good neighbor.
Consult these resources for more help securing your plant:
- American National Standard for Equipment, Design & Installation of Ammonia Mechanical Refrigerating Systems, ANSI/IIAR-2 1999
- American National Standard: Safety Code for Mechanical Refrigeration, ANSI/ASHRAE 15
- Standard for Site Security Services for Fire Prevention (NFPA 601)