this thread makes it sound like some of the air in the pipe is diffusing into the water causing the pressure to lower.
https://www.eng-tips.com/viewthread.cfm?qid=376058
@HatBeard started
London Fixed Gear and Single-Speed is a community of predominantly fixed gear and single-speed cyclists in and around London, UK.
This site is supported almost exclusively by donations. Please consider donating a small amount regularly.
this thread makes it sound like some of the air in the pipe is diffusing into the water causing the pressure to lower.
https://www.eng-tips.com/viewthread.cfm?qid=376058