Breathing Air Compressors for Oil & Gas Rigs

Offshore or onshore oil rigs are hazardous working environments where a variety of hazardous gasses threaten the workers’ lives.  The most common of these gasses is hydrogen sulfide (H2S). It is a toxic, flammable, and corrosive gas often encountered during hydrocarbon exploration and production.

To ensure the safety of the personnel working on these potentially hazardous drilling sites, it is essential to have a suitable breathing air system for workers in case of unsafe H2S concentration levels.

Compressed breathing air is an important safety requirement for all offshore and onshore oil rigs. It is usually delivered using high-pressure reciprocating compressors that are highly efficient delivering compressed gas. Usually, self-contained breathing apparatus (SCBA) with the capacity of 200 liters (lasting 15 min) are kept at a few critical and defined locations on the rig. There must be at least one SCBA bottle per person on board to allow the workers to reach a safe assembly point in an emergency. At the assembly point, the workers disconnect from cylinders and connect to manifolds directly.

A centralized breathing system is active during emergencies at these assembly points. The high pressure in the cylinder bank is regulated down to 7 to 8 bar(g) and distributed to low-pressure breathing air manifolds in the assembly points.

Typically, the compressors used are either 3 or 4 stage units that can compress air from atmospheric (0 barg) up to 250 to 400 barg. The compressor cylinder stages and sizes along with the motor size and speed dictate the charging rate and, in turn, the time to replenish the cascade system.

Breathing air compressors are devices that provide clean and pressurized air for the workers and equipment on oil & gas rigs. They ensure the safety of personnel on the rig by preventing exposure to harmful air contaminants or insufficient oxygen levels. This is why it is a huge responsibility to choose an appropriate compressor that delivers quality breathing air for the oil & gas industry. Some factors to consider when choosing a compressor are compressor size, air quality and purity, compressor reliability and maintenance requirements. 

If you want to choose the optimum breathing air compressor for your oil & gas rig, you should consider the size and reliability of the equipment and the quality of air it delivers. Here are some tips to help you make up your mind:

• Compressor Size

Oil & gas rigs typically rely on a cascade filling system. It is a high-pressure gas cylinder storage system that is used for the refilling of smaller SCBA bottles. It involves numerous cylinders or bottles stacked in a cascade system, storing huge volumes of air at around 300 bar.

Cascade systems are designed to provide a minimum of 1 hour of breathing air per person during an emergency. One person consumes 8 to 10 liters of breathing air per minute. Based on the number of individuals on board, you can determine the volume of breathing air need in case of an emergency and the size of the cascade system. This is the basis of selecting a breathing air compressor. Once you know the required cascade system capacity, you can easily determine the flow rate and pressure requirements your perfect breathing air compressor should have.

• Breathing Air Grade

According to the Occupational Safety and Health Administration (OSHA), any breathing air provided for use in a SCBA must comply with the CGA Grade D breathing air standard. The OSHA defines Grade D air as suitable for breathing with the following characteristics: oxygen content of 19.5-23.5 percent, condensed hydrocarbons & particulates < 5mg/m3 at NTP, CO <10 ppm, carbon dioxide <1000 ppm.

A breathing air compressor must meet the requirements of the above CGA Grade D standard.

• Product Reliability

Oil & gas rigs can be located on land (onshore) or in the sea (offshore). Offshore rigs are often in the middle of the ocean, where they face harsh conditions due to winds, waves, saltwater, and corrosion. Therefore, the breathing air compressors installed on these rigs must be able to withstand these conditions and work reliably in spite of them. As the breathing air compressors play a crucial role, delivering clean and pressurized air for the workers and equipment on the rigs, they must be designed to handle harsh conditions, humidity and high ambient temperature (often ~ 50 Deg C).

• Maintenance

The service providers who operate and maintain breathing air compressors expect low maintenance and longer life of these consumables.

This is important for several reasons. Low maintenance and durability reduce the operational costs and downtime at the rigs, as the compressors do not need frequent repairs or replacements. The compressor reliability and performance also improve as the frequency of breakdowns or malfunctions, which could compromise the quality of the air or the productivity of the rigs, goes down. What is more, low-maintenance and durable equipment improves the safety and health of the workers, preventing exposure to harmful contaminants or insufficient oxygen levels.