Reducing Toxic Leaks in HVAC Mechanical Equipment Rooms

Inside the heating, ventilation, and air conditioning (HVAC) mechanical rooms supporting corporate campuses, industrial plants, large commercial buildings, and institutional facilities, it is crucial to guarantee there is a working environment which is safe.

Safety protocols and strict guidelines must be observed to prevent tragic accidents which can happen when failing to monitor those areas for leaking refrigerants, toxic or combustible gases.

The method most frequently employed for the avoidance of accidents is to audit safety systems in the HVAC mechanical rooms to check the installation of the correct gas detectors, and also the recommended installation location, to give the proper protection.

This should be done regularly; it is crucial to make sure this is done whenever boiler, HVAC, fuel or electrical equipment is upgraded or retrofitted or to support new functional requirements, like those undertaken to improve energy efficiency.

The safety industry has worked hard over the past ten years to enhance the power of toxic, refrigerant and combustible gas sensors. Better communications and intelligence abilities have been included at both the sensor and systems levels because of the utilization of the most up to date digital technologies. This quickly evolving technology means the latest generation of systems and sensors are less prone to false alarms, are more robust, and are easier to maintain and install.

Figure 1. Mechanical Equipment Room Overview

HVAC Rooms

A building’s mechanical room is the center of its air conditioning, heating, and ventilation systems. This can include:

• Fuel rooms
• Central utility plants
• Chiller and boiler rooms
• Electrical and mechanical rooms

There is a potential for leaks to occur because of the equipment housed within such rooms. This can include the leaking of refrigerants, combustible and toxic gases which are costly, dangerous, and damaging to the environment.

Refrigerants have a relatively low toxicity, but they are still classified as a toxic gas, which could be surprising for some who work with them. Despite their low toxicity, at high concentrations, refrigerants can displace oxygen and oxygen deprivation can result in accidental injury or death by means of suffocation. Death or injury in this way is a direct violation of safety regulations under OSHA.

These chemicals are controlled substances regulated by the U.S. Environmental Protection Agency (EPA), meaning they are dangerous to the health and safety of workers and also harmful to the environment. A number of refrigerants are classified as ozone depleting and as such are highly scrutinized. Gas detectors satisfy the requirements for equipment room emissions monitoring included in the EPA regulations.

In addition to EPA regulations, there are regulations of the American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE) Standard 15, plus any local and state building codes. The regulations under ASHAE 15 are as follows:

1. Each machinery room shall contain a detector located where a refrigerant leak would concentrate
2. The detector shall trigger an audible and visual alarm both inside and outside the mechanical room and activate mechanical ventilation

Detector Placement

The detectors utilized to observe refrigerant leaks should not be mounted to HVAC structures that are prone to shocks and strong vibrations, like piping. They should be mounted to the unit vertically and not located in close proximity to direct solar heating, excessive heat sources, or in a damp or wet location. For proper cooling, it is recommended to leave at least three inches of clearance around all surfaces besides the mounting surface.

Sample Point Locations

A gas sample point can be remotely located up to 150 ft (46 m) from the monitor (500 ft. [152 m] for 0.18” [4.6 mm] ID tubing) in a location where refrigerant vapors are more likely to accumulate or leak, depending on the gas monitoring system manufacturer’s recommendations. The capability of the unit to detect leaks is greatly improved by placing the sample point close to the barrel of the chiller and on the adjacent corners.

It is recommended to monitor locations such as stairwells, pits and trenches: As refrigerants are heavier than air. If viable, monitor the vent line of the chiller. Don’t forget to observe the cylinder storage area if close to the chiller room or inside, in case of cylinder leakage.

Choosing a Gas Monitoring System

There are a number of refrigerant gas detector and monitoring systems designed for refrigerant applications in mechanical rooms, which are available from various manufacturers. There are advantages for each model, whilst a number of them also have their own limitations.

It is beneficial to identify a list of key monitoring abilities necessary to your own individual needs. To help with a checklist here are some sample questions to ask suppliers:

• Is the system capable of multi-point monitoring and can this easily be expanded?
• Does the system comply to the regulations stated under ASHRAE 15?
• Does the system controller include integrated BACnet or Modbus for direct digital communication to the facility’s centralized control system?
• Does the controller have multiple relays for fault and alarm alerts, as well as connection to a horn and strobe (required by ASHRAE 15)?
• What ppm level is required for the detection of gas?

Figure 2. Refrigerant Leak Monitoring System

Before purchasing a detection system be sure to consider the setup requirements to make sure the system has plug-and-play capability, which eliminates the need for time-consuming configuration. It is also advised to ask about the maintenance requirements, as well as the frequency of the maintenance.

Conclusion

To guarantee the maintenance of a safe working environment it is crucial to follow safety regulations when working with refrigerants. Refrigerants are toxic and can lead to worker accidents, injury or even death due to oxygen deprivation, are expensive and are harmful to the environment. With the newest generation of refrigerant gas monitoring systems that meet ASHRAE 15 these issues can be avoided. These systems are able to detect gas quickly, and are easy to use and install.

This information has been sourced, reviewed and adapted from materials provided by MSA - The Safety Company.

For more information on this source, please visit MSA - The Safety Company.