<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head>
<body>
<font face="Arial">On pumpkin cannons I've seen ball valves with a
way to turn it fast. Could be as simple as a spring with a rope
you cut. If you needed electrical control, a pneumatic piston
fired by a solenoid. <br>
<br>
For the lowest of dead simple, a wheel for a handle on the valve,
wrap with rope... yank.<br>
</font><br>
<div class="moz-cite-prefix">On 09-Dec-25 21:40, Joe via Stagecraft
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:203061873.2342770.1765305617832@mail.yahoo.com">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<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>"
moz-do-not-send="true"><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>
<div><br>
</div>
<div><br>
</div>
<div id="ydpdfa0c19yahoo_quoted_5924505300"
class="ydpdfa0c19yahoo_quoted">
<div
style="font-family:'Helvetica Neue', Helvetica, Arial, sans-serif;font-size:13px;">
<div> On Monday, December 8, 2025 at 11:39:25 PM EST, Jon
Lagerquist via Stagecraft
<a class="moz-txt-link-rfc2396E" href="mailto:stagecraft@theatrical.net"><stagecraft@theatrical.net></a> 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>
</div>
</div>
</div>
<br>
<fieldset class="moz-mime-attachment-header"></fieldset>
<pre wrap="" class="moz-quote-pre">____________________________________________________________
For list information see <a class="moz-txt-link-rfc2396E" href="http://stagecraft.theprices.net/"><http://stagecraft.theprices.net/></a>
Stagecraft mailing list
<a class="moz-txt-link-abbreviated" href="mailto:Stagecraft@theatrical.net">Stagecraft@theatrical.net</a>
<a class="moz-txt-link-freetext" href="http://theatrical.net/mailman/listinfo/stagecraft_theatrical.net">http://theatrical.net/mailman/listinfo/stagecraft_theatrical.net</a>
</pre>
</blockquote>
<br>
</body>
</html>