Frequently Asked Operating Questions
QUESTION: How do you maintain the operating pressure of O2 up enough to maintain constant diffusion through the tubing?
ANSWER: We use a simple regulator to control pressure and manual venting of the lines periodically to refresh the gas within the tubing (vent out gases that diffuse from the water INTO the tubing). The use of an automated gas management control system is advised which would include the following basic features: control oxygen pressure (and allow it to be varied by the operator); allow venting of the oxygen lines for brief a period ideally one or more times a day but no less frequently than weekly (operator should be able to adjust this frequency); the duration of the period of venting may depend on the configuration of the supply and venting system, number of emitters, etc. The idea is to be sure to blow out all the gases in the tubing of each emitter and thus refresh them with pure oxygen. allow control of a reasonably large number of emitters with one control system , e.g. up to 10 well’s worth of emitters (more than one emitter could be in each well, but would be connected in series and act like one emitter). Thus if an application required more than 10 well locations, the application should likely be divided into a number of separate CHANNELS, each of which would be separately controlled, vented and monitored have some ability to shut down any channel which develops a leak ideally have ability to alert operator if: pressure to emitters rises beyond specified maximum levels (LDPE = 90psi, Silicone tubing = 25psi) pressure to emitters decreases below a specified minimum level, e.g. due to a leak, exhaustion of oxygen supply, etc.
QUESTION: Have you determined the effects of erosion of the tubing by water, aging of tubing material, or biofouling of the surface for any long-term operation?
ANSWER: Neither polymer has shown signs of aging (i.e. deteriorating performance) over 1.5 years of field use. A reasonable estimate of useful life for silicone tubing would be 2-3 year life under typical operating conditions and groundwater environments (ie. only dissolved contaminants present). It is expected that LDPE would last up to approximately 5 years life under typical operating conditions and groundwater environments.
QUESTION: Any idea on how often the coils need to be serviced or replaced?
ANSWER: The PVC frame should not need replacing, only the polymeric diffusive tubing would need to be replaced as estimated above.
QUESTION: How often does the system need to be monitored to maintain sufficient oxygen release (once a week, twice a week, etc.)?
ANSWER: The gas supply and management system should have an alarm feature to alert operators of low gas supply pressure, leaks, etc.
