<html><head></head><body><div class="ydpdfa0c19yahoo-style-wrap" style="font-family:Helvetica Neue, Helvetica, Arial, sans-serif;font-size:16px;"><div><div dir="ltr" data-setdir="false">First, it is good that Jerry Durand reminded folks about the explosion risks with PVC pipe. I reminded the folks working with me about that, so I at least reduced the temptation to see how loud they can make it. I accidentally created a safety feature on my system by using a bicycle pump that was designed for higher volume and lower pressure. Taking it to 70psi was the maximum they had enough weight to pump.</div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false">I understand the Cv rating (resistance to air flow). When I searched for blast valves for dust collection systems. However, all the ones I found were ball, or knife-gate valves. None automatically opened at a certain pressure, or reset. They were simply valves to direct the air flow to the tool being used. I am puzzled why they called them blast valves.</div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false">Here is a quick sketch of how I might imagine a type of resettable high pressure valve might work. Structurally, it is like the air outlet of your clothes dryer, or bathroom exhaust fan. However, I added a magnet to hold the flap closed until pressure exceeds its holding power. The spring loaded hinge on the flap would then close the flap, so it can be used again.</div><div dir="ltr" data-setdir="false"><img title="Inline image" alt="Inline image" src="cid:0dd3df15-bb87-2450-2bcd-14858f533c0c@yahoo.com" class="yahoo-inline-image" style="max-width: 800px;" draggable="false" data-id="<0dd3df15-bb87-2450-2bcd-14858f533c0c@yahoo.com>"><br><br><br>But, I can't find any type of air valve like this, or that is designed for releasing at a fairly high pressure (i.e. 60psi).</div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false">Jon, can you provide a link to the type of valve you were talking about?</div><div><br></div><div class="ydpdfa0c19signature"><div style="font-family:Helvetica, Arial, sans-serif;font-size:16px;"><div dir="ltr" style="font-family:Helvetica, Arial, sans-serif;font-size:16px;">-Joe</div></div></div></div>
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On Monday, December 8, 2025 at 11:39:25 PM EST, Jon Lagerquist via Stagecraft <stagecraft@theatrical.net> wrote:<br clear="none">For valves I found that "blast valves" designed to clean dust collection systems do a great job. I remember them having a CV of about 50.this means they are making a big hole very fast so lots of air moves quickly, producing a good sound with or without a cap.</div>
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