title: Failure and life cycle evaluation of watering valves.
abstract: Automated watering systems provide a reliable source of ad libitum water to animal cages. Our facility uses an automated water delivery system to support approximately 95% of the housed population (approximately 14,000 mouse cages). Drinking valve failure rates from 2002 through 2006  never exceeded the manufacturer standard of 0.1% total failure, based on monthly cage census and the number of floods. In 2007, we noted an increase in both flooding and cases of clinical dehydration in our mouse population. Using manufacturer's specifications for a water flow rate of 25 to  50 mL/min, we initiated a wide-scale screening of all valves used. During a 4-mo period, approximately 17,000 valves were assessed, of which 2200 failed according to scoring criteria (12.9% overall; 7.2% low flow; 1.6% no flow; 4.1% leaky). Factors leading to valve failures included residual  metal shavings, silicone flash, introduced debris or bedding, and (most common) distortion of the autoclave-rated internal diaphragm and O-ring. Further evaluation revealed that despite normal autoclave conditions of heat, pressure, and steam, an extreme negative vacuum pull caused the valves'  internal silicone components (diaphragm and O-ring) to become distorted and water-permeable. Normal flow rate often returned after a 'drying out' period, but components then reabsorbed water while on the animal rack or during subsequent autoclave cycles to revert to a variable flow condition.  On the basis of our findings, we recalibrated autoclaves and initiated a preventative maintenance program to mitigate the risk of future valve failure.
authors.affiliation: The Salk Institute for Biological Studies, Animal Resources Department, La Jolla, California, USA. Gonzalez@salk.edu
authors.forename: David M
authors.initials: DM
authors.lastname: Gonzalez
authors.forename: Sandy J
authors.initials: SJ
authors.lastname: Graciano
authors.forename: John
authors.initials: J
authors.lastname: Karlstad
authors.forename: Mathias
authors.initials: M
authors.lastname: Leblanc
authors.forename: Tom
authors.initials: T
authors.lastname: Clark
authors.forename: Scott
authors.initials: S
authors.lastname: Holmes
authors.forename: Jon D
authors.initials: JD
authors.lastname: Reuter
mesh_terms: D000822:Animal Husbandry / Q000295:instrumentation*; D000818:Animals; D000830:Animals, Laboratory; D060766:Drinking Water; D019544:Equipment Failure Analysis; D006799:Housing, Animal; D051379:Mice; D012499:Sanitation / Q000379:methods*
chemical_list: D060766:Drinking Water