Pressurized Glue Manifold Design

[qnen]

In a certain line of packaging equipment, we use cold glue to glue flaps of a container together. The glue is applied with a vendor supplied glue gun. (the gun is about the size of a pack of cigarettes, with a nozzle on one end, and glue supplied from the other, and an electrical solenoid to "fire" the gun). Up to now, a single gun was used in conjuction with the vendor supplied hose assembly, pump, etc.

Now the design calls for mounting 12 guns in an array. Due to the location within the machine, there isn't room to run 12 supply hose assemblies into the machine from the glue pump/controller. One idea is to create a manifold inside the machine and have short hoses connect the manifold to the guns. One person feels that 1" dia pipe with 12 fittings mounted on it will suffice. I have concerns about the integrity of the pipe once it's been drilled and welded on and then presurized.

The glue supply is at about 500psi. I don't normally deal with designing pressurized manifolds, so I am looking for a little guidance. I realize that this is a wide open ambiguous question, but it is a starting point.

Thanks

Michael Kuehnen, Kansas City

 

[MikeHalloran]

If you're uncomfortable with drilled and welded manifolds, consider stringing together a line of 'street tees' to make a manifold out of standard parts.

Or just have a machine shop make one by drilling and tapping barstock.


Mike Halloran
Pembroke Pines, FL, USA

 

[handleman]

Depending on the viscosity of the glue and the dispensing accuracy required, just a manifold may not get you the application you want. The nozzles near the incoming supply will almost certainly dispense more glue. How much more will be a function of the viscosity and manifold/fitting geometry.

-handleman, CSWP (The new, easy test)

 

[jlnsol]

In the 'hot melt world' it is quite common to use manifolds, for instance google this: POWERBOND G100 4 BEAD MODULE, MANIFOLD.

 

[LittleInch]

qnen, I thnk you're right to be concerned. Assuming that someone has adequately dealt with whether your system is able to cope with expansion from 1 to 12 guns, then normally a sensible sizing of a manifold is to add up the internal square area of all the outlets, assuming they can all flow at more or less the same time, then sqrt the summ to find the ID of your manifold. It might not be precise, but gives you a good starting point of what you need to prevent the manifold becoming a bottle neck.

You are a bit vague as to what the "fittings" are that someone plans to weld on to your 1" pipe. What ever it is should be designated as a profiled fitting designed for this purpose so that it doesn't protude into the manifold and has sufficient re-inforcment to prevent stress concentration at the joint between "fitting" and manifold.

Standard tees as MH suggests welded or joined togehter or weldolets into a larger manifold - 2", 3"?? would be much stronger and able to survive the exernal loads and any pulsation / fatigue loads. One you cut a hole in a piece of pipe of more than about 25% of its ID, then you severely weaken it and it needs to be strenghtend properly to avoid failure. As jlnsol has shown above, you can get ready made manifolds which already address all these concerns and issues - doing it yourself as you describe without the right experience seems like a bad idea. If you need to do something specific because of space etc, then make sure someone who understands pressure equipment looks at it and make sure it's tested to 1.5 x its design pressure first.

Good luck

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[jlnsol]

add up the internal square area of all the outlets, assuming they can all flow at more or less the same time, then sqrt the summ to find the ID of your manifold

This was exactly what I did when I designed my first manifold for supplying 10 lanes of sirup on a cake sheet in a food processing line 15 years ago. It consisted of one pump with supply hopper and a disharge pipe connected to an aluminum milled manifold with 10 small outlets. There where no valves or so, just an open system intended to evenly distribute the sirup. It didn't work out well. It gave uneven weight samples between the lanes. An expert from a company who delivers manifold systems for choclate supply learned me why. To be sure all outlets will be 'used' for discharging the fluid supply evenly it is better to create a pressure increase. So one should add up all the internal square area of the outlets, then TIMES 2 in order to find the square area of the manifold inlet. Since that time I visualise this problem always by referring to those ventilation ducts which you often find hanging to the ceiling in food processing plants to bring in cold air. A huge inlet of air and not enough small outlets causing a full blown duct and good distribution.
My two cents.

 

[LittleInch]

That's fair enough, especially when dealing with viscous products and they are all potentially flowing at the same time. I usually work with crude oil and refined products / gas which are much less viscous. Even distribution from a manifold with many outlets and no other controls is very hard, but I fully accept the principle you came up with.



My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way