Quote:
Originally Posted by Why_A_Username?
The gist of what i got from your post is that basically flow rate is equal too, if not greater than PSI in importance, because it is hard to maintain a constant PSI. We want a fast-fireing solinoid with a wide flow in between the resovior and the barrel tube to minimize the pressure drop between the two. Our current design has multiple barrels so thst presents a challange for multiple resovior connections. Thanks for the great reaponse!
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What you really care about is PSI at the point of delivery (base of the barrel). If the T-Shirt could magically travel down the barrel without flow, you would essentially try to pull a vacuum on the tube, as an extremely small volume of starting air expands to try to fill the tube. The more air you flow into the tube, the more pressure you will have throughout the travel of the T-Shirt, and the more total force imparted.
Flow and starting pressure are linked of course, such that a higher pressure can drive a higher flow through the same size solenoid/tubing, etc. However, the pressure loss is exponential as tubing and orifice sizes decrease, and you are ultimately limited by what is called "choked flow". Simply put, air can not travel faster than the speed of sound in the gas system, so if there is a tight enough restriction, increasing pressure further doesn't add more flow.
Therefore, your solenoid does need to be "fast firing" but also have a large flow orifice (specified as a Cv value, which is basically the total flow across a valve for a unit pressure drop... bigger is better for this). A typical FRC solenoid will not work well for this application.
Multiple barrels and multiple connections is not as much of a design challenge as a cost challenge, if you wanted to have a solenoid valve per barrel. You could also consider (if you really wanted to push the envelope) of a revolver style design with a single barrel and a t shirt magazine that advances through it. There you still just need a single solenoid, and the main challenge is getting a good seal between the barrel and magazine.
Feel free to keep asking questions. Gas system design was my day job for a number of years.