The Knock Knock children's museum in Baton Rouge is set to open this August. We are delighted to have participated in one of the principle attractions, the pneumatic tube carrier exhibit. Designed by Zaphod Beeblebrox, the helix consists of a a spiral of 60 degree bends, rotated couplings, and entrance and exit bends.
Angel hairs and tube abrasions are the nemesis of cap and closure conveyance.On Apr 1, 2009 Shrikant Dhodapkar (and others) published "Understanding Bends in Pneumatic Conveying Systems" in Solids Processing. The document is widely available online. The article has excellent graphics on various bend's styles designed to minimize abrasions. This is nothing new to us. We have made expanded bends for decades out of CAB.
We recently had an inquiry for a tight-radius Ubend. This 1" OD bend x .125w in CAB (butyrate) has a tight center-line radius of 2.5" with uneven tangents. Not only do we have to design the proper heater for this bend, and select the proper packing material, but have to estimate and adjust for the "pull-in" that is associated with thermoplastic 180 Deg bends. Here is our prototype.
Busada pneumatic tubing consists of three major parts; the tube, the bend, and the sleeve. The tube is designated by Outer Diameter, and Wall, from the Wall we extrapolate the Inner Diameter. The Inner Diameter is crucial to the part being conveyed (it may be a canister, a cup, powder, pellets, caps, etc.) Likewise, a bend's critical dimension is the Inner Diameter (we are not considering radius here). In order to connect a bend to a straight tube, one needs a coupling. The sleeve, however, has one critical dimension, and that is its Inner Diameter.
An electrical manufacture had a need for a small quantity of clear, transparent tubing sleeves for their line of ¼” wide blade-type quick connects. We provided them with long sleeves of 2.765" ID (about 16" long). The extrusion was in CAB, cellulose acetate butyrate. In extrusion, the ID of a tube is derivative of the OD and the Wall. The best way to check an ID is to make go no-go gauges or to machine a steel or aluminum ball (if the sleeve is bent). We generally extrude sleeves with an ID average that is .015 to .020 larger than the tube that it connects. Our extensive line of stock tubing and our low-minimums allow us to take on the small orders efficiently.
Pax Bellum contacted us regarding their macro-algae bio-absorption filters for the aquaculture and aquarium industry. The devices use a central light assembly consisting of a plurality of LEDs affixed to a water pipe or heat pipe. They were looking to replace the clear tube separating the LED array from the system water (currently polycarbonate.) After a few months in salt water and going through thermal cycling would cause crazing and stress fracturing.
Recently one of our customers south of the border had difficulty moving cups through a complex space. We suggested eliminating multiple bends with snake and offset bends. The result was eliminating over 50% of their bends and really neatening up the floor space. Contact us for any pneumatic conveyance needs and we'll put our know-how to work.