Conveyer Dryer Airflow Problem--I'm thinking of a rooftop air handler....

[Itsa Little CrOoked]

I have a fan that keeps failing in my Harco (Brown) UC3611 infra-red oven. Nothing is going to change that long term, since it's actually a design flaw exacerbated by the fact that you can't buy a fan motor without thermal overload protection. CURRENT overload protection is a different issue, handled by the breaker panel, but when the fan gets too hot, it shuts off. I"ll fix it, and it works fine for a year or so. Then its off to the warehouse for another motor.

I want more reliability, and more airflow, if I can get it. I got a dose of discharge fumes yesterday and I think I may have some Drain Bramage. 

I am adding this today: http://www.amazon.com/910-Acme-Miami-Inline-Duct/dp/B004TBXKW6  inline in my 12' ducting stack, which is vertical all the way to the roof termination.

Any additional ideas?  I'll bet someone on this board has walked this path before.

Thanks!
Stan

EDIT.... PREVIOIUS LINK WAS WRONG, SORRY. THE ABOVE SHOULD WORK NOW. It's that whole drain brammage thang......

[Binkspot]

They do make high temp motors that will handle the heat (Graingers will have them). Most TEFC motors can handle well over 200 degrees continuous duty for many years.

Make sure the exhaust outlet is not blocked causing back pressure. Even though you have a 12" duct a rain cap or bird guard may be restricting the flow acting like a 6" duct. The mfg should have a spec for max back pressure which can easily be checked with a home made slack tube manometer with some clear plastic tubing a ruler and some water. Back pressure can easily create an over load/heat condition in a fan.

Try Cincinatti Fan or Hartzel Fan

[Itsa Little CrOoked]

Excellent Binkspot!  I was told I probably couldn't buy those.  And we have a Grainger in Wichita.

I'm going to poke around on the Grainger online catalog this evening and see what I can find.  Even if it isn't a direct replacement but can be adapted, a little sheet metal work and farmboy headscratchin' might make it work.

I wish I could BOOST the airflow just a bit also, from the level I have now when everything is working. I am a manual shop but even so, when I print discharge on a one color design, I wait on the dryer a little.  I could probably push it faster, but I want to be on the plus side of the margin of error, because undercured discharge prints are a problem with my short dryer. The chamber is 6' and I try to stay under the heat for 3 minutes, out at about 330 with a point and shoot heat gun. If I set the heat much higher, I fight scorching on white shirts with Waterbased inks.  My shirts usually wash pretty well, but if I could go through 30 seconds faster and still pass a test wash, I'd be in tall cotton. It took a TON of experimenting to hit the right speed/temp settings for discharge--day in, day out.

[Binkspot]

You would have to find a distributor but also check Baldor motors, Marathon and Magtek. You could also check a local motor shop who could set you up with the proper equipment.  I have had motors modified for special purpose in the past dealing with local shops.

[Frog]

Doesn't increasing exhaust power actually reduce efficiency of the dryer itself?

[Inkworks]

Depeends on the venting design of the dryer. In my old Hix it doesn't change the in-tunnel temp much because it's like a box around the tunnel. I use one of these fans:



they are quite a bit more expensive than the one pictured in the first post, but also quieter and can have variable speed, which is a huge asset as sometimes you want a little, sometimes you want a lot. I have it plumbed in about 20' away fro the dryer, which allows a little bit of a temp drop in the exhaust so the fan sees less heat than if it was sitting right on top of the oven.

[Itsa Little CrOoked]

Inkworks, can you come up with a make and model number for your blower? I have seen similar units by using google images "inline duct fan" and wording like that. This one looks like what you have, but is too small:  http://www.cedarpc.com/product/21669/CFM-AXC200A-IN-Line-Duct-FAN/

Frog, for definite sure, significantly more airflow will require entirely new temp settings. Perhaps not with a big gas unit, I dunno... 

I have plenty more heat available.  I only keep it down to the minimum temp settings I can use and still hold the discharged shirts between 300 and 330 for a full 2 1/2 minutes without scorching.

This is about like my dryer.The exhaust fan is just under the 12" rim visible on the top right side of this picture...awfully close to the heat.

[Printficient]

Once again.  904-343-0848

[Inkworks]

Inkworks, can you come up with a make and model number for your blower? I have seen similar units by using google images "inline duct fan" and wording like that. This one looks like what you have, but is too small: 

http://www.continentalfan.com/ecatalog.php?fantype=industrial&fid=57&s=In-Line+Fans

Up to 14" diameter inline fans.

I'm not sure the one in the link is my exact one, many look similar, but it does have the option for the solid state speed control, which I opted for and really like, when it's cold up here, like now, I have barely enough air movement to get rid of the fumes and still get a lot of benefit from the radiant heat, in the summer when it's hot (yes it gets hot up here in Canada  ) I turn it up a bit so the central AC is more effective.

We also tune in the fan speed depending on the job, we turn it up a bit more for hoodies and other fleece to keep the haze out of the shop. I hope to be turning it up for Discharge this Jan/Feb when we'll dabble in it a bit...

Mine wasn't cheap ~$180+ with the speed control, and it's just the 8" model, but sometimes stuff up here is almost double what it can be had for down there.

[Itsa Little CrOoked]

180 US sounds fine to me, if it works. I have to avoid what happened Thursday and Friday at all cost.

Stinky stinky stinky. I have a young gal of child bearing age that prints for me in the afternoons, and I'm not exposing her to discharge fumes. Nope..... if I can smell it, she's going home. We are a small Ma and Pa operation and I want to stay a mile away from that Gray area....

[Inkworks]

* I'll add the asterix to check max operatiing temps, and your oven exhaust temps, mines worked well for several years, but the Hix doesn't vent all that hot when running.