Understanding the Pneumatic Flow of Oxygen

The third most abundant element in our universe, oxygen makes up approximately 21% of the earth’s atmosphere. Discovered in the late 16th century, oxygen was once named the “elixir of life.” The benefits of oxygen therapy have been known for centuries. It is no wonder that medicine has focused on methods of oxygen supplementation to enhance and support life. Hospitals and nursing homes are filled with medical devices that regulate, distribute, monitor, or manufacture oxygen for therapeutic use. Biomedical equipment technicians routinely service and maintain these devices and may even be responsible for the medical gas distribution system. Frequently, a medical facility may not have piped gases to each patient area and must depend on other means to provide oxygen therapy. Compressed oxygen is sometimes stored in tanks of various sizes and may be transported with the patient. Portable canisters filled with liquid oxygen are also used to enable patient mobility. Oxygen concentrators are another device that may be encountered where temporary or long-term oxygen therapy is needed. These electrically powered machines, which may be more cost effective to operate than purchasing tanks, do not need to be refilled or replaced. The bulk of the air we breathe is made up of nitrogen, approximately 80%; and oxygen, around 20%. Oxygen concentrators work to provide high levels of oxygen by removing the nitrogen component, concentrating, and then storing the oxygen for use by the patient. Many concentrators provide flow rates up to 5 liters per minute (LPM) and have internal circuitry to monitor the concentration and alert the users when concentrations fall below a set limit. Room air is drawn past filters to remove dust and contaminants, compressed to a determined level and passed through canisters containing zeolite granules. The granules absorb the nitrogen while the oxygen passes through to a storage container. These granules are regenerated during this process, which allows them to strip the nitrogen from the next volume of air that passes through. It is important for the biomed to understand the pneumatic flow of gas through the system along with the theory of operation to be able to troubleshoot problems. Gas filters, check valves, solenoids, and restrictors are all Understanding the Pneumatic Flow of Oxygen