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fraction of a second pressure drop on iso side when the pump changes direction at low point Post New Topic | Post Reply
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Nicolas Salkin
Posted: Oct 08, 2019 05:29 PM
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fraction of a second pressure drop on iso side when the pump changes direction at low point
This is a double vertical cylinder pump, a classical setup, with approx. 5.5 gallons per minute at 60 cycles. All is good excepted... When the machine is working, each time the pistons are at lowest point and just when they reverse their course, from going down to going up, we get a short pressure drop on the iso side. This results in the fan pattern collapsing during a fraction of a second to a straight jet of mixed components, with poor iso ratio, resulting in a small volume or area of bad foam. The pressure drop on the iso side allow more polyol to be delivered. The nice regular circular fan spray collapses during maybe 1/10th of a second, so that most out-of-ratio product is not dispersed but focused on a area maybe 3 inches wide. I dismounted both sides, because I could not find a clue on ISO side. Feeding is from tanks, with half a meter of gravity + 0.5 PSI of nitrogen pressure, going through 2" pipes to a filter. A big 2" filter with stainless steel is perfectly clean, nothing leaks, nothing suspect. Packings are neat, ball valves are pristine, etc. 10 years of no troubles... apart this mystery. Any clues? |
