Respirometers are used for the quantification of respiration in humans or other organisms through measurements of oxygen, water and/or carbon dioxide levels, and mass flow rate. Simple respirometers consist of a sealed container along with the organism being tested, and a substance such as soda lime pellets to soak up the carbon dioxide given off. Oxygen uptake rates are calculated by the displacement of fluid in a glass tube connected to the sealed container.
Respirometers include devices for measuring and analyzing oxygen or carbon dioxide levels. Oxygen respirometers are used to measure aerobic respiration - respiration which requires the presence of oxygen - in plants, small animals and birds, fruit, and soil. Carbon dioxide respirometers are also used to measure anaerobic respiration - respiration which does not require the presence of oxygen - in plants and plant-based products, small animals, insects, and bacterial cultures. In addition, respirometers are used to monitor the exchange of gases that occur in photosynthesis. Both oxygen respiration instruments and carbon dioxide respiration instruments use a mass flow meter or mass flow controller to monitor the flow of gases through a series of valves.
Respirometers are used to monitor both aerobic and anaerobic processes. A respirometer may be used to monitor the biodegradation reactions that take place during the microbial breakdown or hydrocarbons or plastics. For example, specific microbes are used to clean up oil spills. A respirometer designed to measure the level of anaerobic gas can monitor the remediation process. Aerobic testing is also done in remediation applications and includes monitoring the quality of treated wastewater. Aerobic biodegradation occurs when aerobic bacteria are used to break down organic contaminants into smaller compounds. Respirometers used in remediation applications may also measure oxygen uptake rates as well as the toxicity of the remaining compounds in the sludge or wastewater.