{"id":422,"date":"2008-11-27T10:45:18","date_gmt":"2008-11-27T15:45:18","guid":{"rendered":"http:\/\/www.thegatesofdawn.ca\/wordpress\/?page_id=422"},"modified":"2008-11-28T12:37:34","modified_gmt":"2008-11-28T17:37:34","slug":"pneumatic-pinch-valve","status":"publish","type":"page","link":"https:\/\/www.thegatesofdawn.ca\/wordpress\/homebrewing\/pneumatic-pinch-valve\/","title":{"rendered":"Pneumatic pinch valve"},"content":{"rendered":"<p>After successful testing of my <a title=\"3\/8&quot; Pneumatic pinch valve\" href=\"http:\/\/www.thegatesofdawn.ca\/wordpress\/posts\/2008\/11\/25\/pneumatic-pinch-valve\/\">prototype pneumatic pinch<\/a> valve with a 3\/8&#8243; bore, I proceeded to design another version with a full 1\/2&#8243; bore. This version uses silicone tubing instead of latex, which I believe will not contribute any off-flavours, and will not break down eventually as latex tubing is prone to do. In addition, it also has pipe-thread connections for inlet and outlet so it can be plumbed into a system easily, but can be removed if necessary. And no silicone tubing is exposed outside the pressurized jacket, so it won&#8217;t have problems with the tubing inflating and bursting as in the prototype version.<\/p>\n<p>I used all household copper plumbing fittings in this design. Soldered together to form a pressure-tight seal. It&#8217;s quite inexpensive compared to commercially-available solenoid valves.<\/p>\n<p><a href=\"http:\/\/www.thegatesofdawn.ca\/wordpress\/wp-content\/uploads\/pinchvalve_iso.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-416 aligncenter\" title=\"pinchvalve_iso\" src=\"http:\/\/www.thegatesofdawn.ca\/wordpress\/wp-content\/uploads\/pinchvalve_iso-300x217.png\" alt=\"\" width=\"300\" height=\"217\" srcset=\"https:\/\/www.thegatesofdawn.ca\/wordpress\/wp-content\/uploads\/pinchvalve_iso-300x217.png 300w, https:\/\/www.thegatesofdawn.ca\/wordpress\/wp-content\/uploads\/pinchvalve_iso.png 563w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/a><\/p>\n<h3>Parts<\/h3>\n<p>Here are the parts I used:<\/p>\n<ul>\n<li>3\/4&#8243;x1\/2&#8243;x1\/2&#8243; copper reducing tee<\/li>\n<li>3\/4&#8243;x1\/2&#8243; copper reducer coupling<\/li>\n<li>Two 2&#8243; lengths of 1\/2&#8243; copper pipe<\/li>\n<li>One 1&#8243; length of 1\/2&#8243; copper pipe<\/li>\n<li>One 2&#8243; length of 3\/4&#8243; copper pipe<\/li>\n<li>Two copper 1\/2&#8243; socket x 1\/2&#8243; FPT adapters<\/li>\n<li>Copper 1\/2&#8243; socket x 1\/4&#8243; FPT adapter<\/li>\n<li>3&#8243; length of 1\/2&#8243;ID silicone tubing (obtained from a local industrial supplier, <a title=\"Rubberline\" href=\"http:\/\/www.rubberline.com\/\">Rubberline<\/a>.)<\/li>\n<\/ul>\n<p>The reducing tee and the reducer must both be drilled through with a 5\/8&#8243; bit, to remove the stops that normally limit the depth of copper tubing being inserted. We need to run a length of 1\/2&#8243; copper pipe straight through, so the stops must be removed. Drilling with a 5\/8&#8243; bit does most of the work, then a little more work with a small round file and some elbow grease will allow the copper pipe to slide through without too much resistance.<\/p>\n<h3>Assembly<\/h3>\n<p>Here&#8217;s how the pieces fit together:<\/p>\n<p><a href=\"http:\/\/www.thegatesofdawn.ca\/wordpress\/wp-content\/uploads\/pinchvalve_exploded.png\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-414\" title=\"pinchvalve_exploded\" src=\"http:\/\/www.thegatesofdawn.ca\/wordpress\/wp-content\/uploads\/pinchvalve_exploded.png\" alt=\"\" width=\"496\" height=\"193\" srcset=\"https:\/\/www.thegatesofdawn.ca\/wordpress\/wp-content\/uploads\/pinchvalve_exploded.png 748w, https:\/\/www.thegatesofdawn.ca\/wordpress\/wp-content\/uploads\/pinchvalve_exploded-300x117.png 300w\" sizes=\"(max-width: 496px) 100vw, 496px\" \/><\/a><\/p>\n<p>First assemble the silicone tubing with the two lengths of 1\/2&#8243; pipe, overlapping by about 1\/2&#8243;. It&#8217;s a bit of a stretch, but it&#8217;s doable. I would have liked to put some kind of hose-clamp on here, but there isn&#8217;t enough space for it inside the 3\/4&#8243; pipe. In testing, it appeared that the simple friction fit seemed to withstand household water pressure, around 48psi in my house.<\/p>\n<p>If you&#8217;ve never soldered copper tubing before, you might want to look over my <a title=\"Quick introduction to soldering\" href=\"http:\/\/www.thegatesofdawn.ca\/wordpress\/homebrewing\/wort_chiller#Soldering\">quick introduction<\/a>.  The most important things to know are: lead-free solder, use acid paste flux, and clean, clean, clean.<\/p>\n<p>Clean (with wet-sandpaper or a steel brush) and apply solder paste to the end of the 1\/2&#8243; pipe, to the 1\/2&#8243; port on the tee, and the 1\/2&#8243;FPT adapter. Insert the 1\/2&#8243; pipe into the 3\/4&#8243; side of the tee, and out the 1\/2&#8243; side. Slide the 1\/2&#8243;FPT adapter on the end, and solder both the adapter and the tee.<\/p>\n<p>Clean and paste one end of the 3\/4&#8243; pipe and the 3\/4&#8243; port on the tee, and solder those together.<\/p>\n<p>Clean and paste the other end of the 3\/4&#8243; pipe, the other end of the 1\/2&#8243; pipe, both ports on the reducer, and the other 1\/2&#8243;FPT adapter. Slide the reducer over the end of the 1\/2&#8243; pipe and slide it along to mate with the 3\/4&#8243; pipe. Slide the 1\/2&#8243; FPT adapter onto the end. Solder at both ends of the reducer, and the FPT adapter.<\/p>\n<p>Finally, clean and paste both ends of the remaining piece of 1\/2&#8243; pipe, the 1\/2&#8243; branch of the tee, and the 1\/4&#8243;FPT adapter. Assemble them together, and solder both joints.<\/p>\n<p>Here&#8217;s a cutaway view of the finished product:<\/p>\n<p><a href=\"http:\/\/www.thegatesofdawn.ca\/wordpress\/wp-content\/uploads\/pinchvalve_section.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-432 aligncenter\" title=\"pinchvalve_section\" src=\"http:\/\/www.thegatesofdawn.ca\/wordpress\/wp-content\/uploads\/pinchvalve_section-300x123.png\" alt=\"\" width=\"300\" height=\"123\" srcset=\"https:\/\/www.thegatesofdawn.ca\/wordpress\/wp-content\/uploads\/pinchvalve_section-300x123.png 300w, https:\/\/www.thegatesofdawn.ca\/wordpress\/wp-content\/uploads\/pinchvalve_section.png 680w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/a><\/p>\n<p>And a photograph of the real-world one:<\/p>\n<p style=\"text-align: center;\"><a href=\"http:\/\/www.thegatesofdawn.ca\/wordpress\/wp-content\/uploads\/img_0275.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-417 aligncenter\" title=\"img_0275\" src=\"http:\/\/www.thegatesofdawn.ca\/wordpress\/wp-content\/uploads\/img_0275-300x199.jpg\" alt=\"\" width=\"300\" height=\"199\" srcset=\"https:\/\/www.thegatesofdawn.ca\/wordpress\/wp-content\/uploads\/img_0275-300x199.jpg 300w, https:\/\/www.thegatesofdawn.ca\/wordpress\/wp-content\/uploads\/img_0275.jpg 800w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/a><\/p>\n<h3>Testing<\/h3>\n<p>I tested the valve controlling my household water pressure, which I have measured at around 48psi. If it can seal 48psi water, then it should have no problem with the 5psi or so that comes from a March 809-HS pump typically used in homebrewing.<\/p>\n<p>In testing, though, I found I couldn&#8217;t really get a tight seal, even at 60psi control pressure. But it did slow it down to an almost undetectable trickle. I&#8217;m not sure why, since the 3\/8&#8243; prototype valve seemed to seal tight at a much lower pressure.<\/p>\n<p>The reason it didn&#8217;t seal perfectly may be related to something I read in the Instrument Engineers&#8217; Handbook (<a title=\"Instrument Engineers' Handbook\" href=\"http:\/\/books.google.ca\/books?id=3MMldd1rwUIC&amp;pg=PA499&amp;lpg=PA499&amp;dq=pneumatic+pinch+valve&amp;source=web&amp;ots=pw54wogAlc&amp;sig=U02jnYut8QW0HxaOnvlWzkWc0Bo&amp;hl=en&amp;sa=X&amp;oi=book_result&amp;resnum=7&amp;ct=result#PPA499,M1\">Google Books page<\/a>): to seal tight, a pneumatic pinch valves needs a control pressure about 45psi above the line pressure. In my case, that would be around 93psi. I&#8217;m a little hesitant to pressurize the copper tubing that much without some more research to see if it&#8217;s safe.<\/p>\n<p>In any case, though, I&#8217;m sure it will be fine for controlling wort flows from a March 809-HS pump. Perhaps I&#8217;ll fall back on an off-the-shelf solenoid valve to control the incoming water supply to my brewing system, and uses these pneumatic pinch valves everywhere else.<\/p>\n<h3>Files<\/h3>\n<ul>\n<li>Google Sketchup <a title=\"Pinch Valve model\" href=\"http:\/\/www.thegatesofdawn.ca\/images\/PinchValve.skp\">model<\/a><\/li>\n<\/ul>\n<ul>\n<li><a title=\"Exploded pinch valve model\" href=\"http:\/\/www.thegatesofdawn.ca\/images\/PinchValve_exploded.skp\">Exploded sketchup model<\/a><\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>After successful testing of my prototype pneumatic pinch valve with a 3\/8&#8243; bore, I proceeded to design another version with a full 1\/2&#8243; bore. This version uses silicone tubing instead of latex, which I believe will not contribute any off-flavours, and will not break down eventually as latex tubing is prone to do. In addition, [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":0,"parent":108,"menu_order":0,"comment_status":"open","ping_status":"open","template":"","meta":{"footnotes":""},"class_list":["post-422","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.thegatesofdawn.ca\/wordpress\/wp-json\/wp\/v2\/pages\/422"}],"collection":[{"href":"https:\/\/www.thegatesofdawn.ca\/wordpress\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.thegatesofdawn.ca\/wordpress\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.thegatesofdawn.ca\/wordpress\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.thegatesofdawn.ca\/wordpress\/wp-json\/wp\/v2\/comments?post=422"}],"version-history":[{"count":8,"href":"https:\/\/www.thegatesofdawn.ca\/wordpress\/wp-json\/wp\/v2\/pages\/422\/revisions"}],"predecessor-version":[{"id":433,"href":"https:\/\/www.thegatesofdawn.ca\/wordpress\/wp-json\/wp\/v2\/pages\/422\/revisions\/433"}],"up":[{"embeddable":true,"href":"https:\/\/www.thegatesofdawn.ca\/wordpress\/wp-json\/wp\/v2\/pages\/108"}],"wp:attachment":[{"href":"https:\/\/www.thegatesofdawn.ca\/wordpress\/wp-json\/wp\/v2\/media?parent=422"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}