By John Brubaker,
A while back I worked in lab with a large laser. We had just moved into this new building and everything was fine for a few weeks, then suddenly the laser would shutdown. I checked the error and it indicated that it was a lack of cooling water flow. The water for this system was the building water, supplied by a 1/4″ tube. The laser kept shutting down. We contacted the plumber who had built the system. He came out and checked everything. The pressure and the flow was fine, well within the requirements for the laser.
Finally I noticed this problem always occurred at approximately the same time everyday, right after lunch. So I called the plumber back and gave him the new information. He noted that right after lunch there was a lot more activity in the restrooms. This would cause dips in the water pressure. His solution was to not use the laser during this times.
Then my old hydraulics training came back to me. I told him to go buy a large well tank and install it on the main water line in the mechanical room near the laser. He thought I was drinking and told everyone it would not work, but my boss had confidence in me and told him to go ahead and do what I said during the next weekend. The following Monday there was a shiny new well tank in the mechanical room. Lunch came and went with no shutdown. The plumber was there and dropped his jaw. I explained to him, as I had before, that the well tank was an accumulator. An accumulator is a container stubbed onto a supply line. The tank is filled with air when it is installed and when the water or oil supply is restored it will maintain the system pressure through dips in the supply pressure. For you electric types, an accumulator works sort of like a motor start cap.