Sawdust Blower power up.

[acco1840]

I have a Richardsons 7 inch sawdust blower at home and am looking at powering it with a small motor, as I have a heap of sawdust to move and no Loader. I have a 6HP chinese knock off of a Yanmar single cylinder diesel engine, and am wondering if it will have enough guts to drive it??

[bandmiller2]

Acco,I kinda doubt that 6hp will run the blower to capacity,but you have to hook the blower up anyhow why not give it a try.Worst you'll have to do is belt up a bigger motor to the already setup blower. Frank C.

[Larry]

Not enough info.  This calculator found in the toolbox will put you in the ball park for a electric motor...you will still have to convert hp from electric to diesel.

https://forestryforum.com/members/donp/Blowercalc.htm

[Meadows Miller]

Gday

Jarrod where you wanting to shift it too how far from the suction point to blower and how far from the blower to the pile as that makes a difference too Mate  ???

Regards Chris

[Brucer]

Rule #1 with fans and blowers: Do not, under any circumstances, run them faster than the nameplate RPM.

Driving a fan or blower directly from a single cylinder engine is not a good idea -- to much vibration. Use a belt drive or a flexible coupling to damp out some of the vibration.

If you're lucky, there will be a plate on the blower somewhere, giving you the design speed and Horsepower. Figure that you'll need twice as much HP from a diesel engine. Have you got enough power? If not, you can slow down the blower using a belt drive. The power required by a blower varies with the cube of the speed. In other words, if you slow a fan down by 80%, you'll need 54% of the rated power (0.8 x 0.8 x 0.8 = 0.54). Of course you won't be moving as much air but it still might be enough for you.

Having trouble getting the engine up to speed? Simple trick -- block the inlet or the outlet until the motor gets up to it's normal operating speed. Intuition says that should take more power, but intuition is wrong in this case. It takes more power to move the air. I've won many a bet with that little tidbit.

Also, if you test a fan and motor out with no ductwork on the inlet and outlet, it will draw more power. Same principle as above. No friction from the ducting, so the fan tries to move a lot more air than it normally would.

[submarinesailor]

Driving a fan or blower directly from a single cylinder engine is not a good idea -- to much vibration. Use a belt drive or a flexible coupling to damp out some of the vibration.

Having trouble getting the engine up to speed? Simple trick -- block the inlet or the outlet until the motor gets up to it's normal operating speed. Intuition says that should take more power, but intuition is wrong in this case. It takes more power to move the air. I've won many a bet with that little tidbit.

Ditto what Brucer stated.

Having performed vibration analysis on 1000's of fans in and around the steel industry, I can tell you what can happen WHEN they get dirty.  Not fun to be around - a 4000 HP ID fan for a blast furnace that is out of balance will make you think not once or twice, but 3 times before going near it to take vibration reading on it. :( :( :(

Also he is dead on about the power required to move air.  In the Energy Management world we call it the Fan Law.  If you have a clamp-on amp meter, use it to check the current flow on it fan with full load and with the inlet or outlet covered.  You will be surprised by the difference.

Bruce

[Brucer]

...  Not fun to be around - a 4000 HP ID fan for a blast furnace that is out of balance will make you think not once or twice, but 3 times before going near it to take vibration reading on it. :( :( :(

And I bet you approached it from the shaft ends  ;D.

That brings up another point. When you test out one of these things, picture in your head what would happen if the impeller blew apart from centrifugal force. The pieces would fly off the sides of the shaft, so be sure to be standing at either end of the shaft, not beside it. Also make sure there's no one else beside the shaft, even a goodly distance away.

You'd almost think I used to work in the fan industry ;D.

[acco1840]

Nice. this is a lot more complex than I thought!! I hooked up the diesel via a v belt and tried it. It does not have an ID plate on the blower, But I used to drive it off my sawmill shaft while cutting. The diesel seemed to do it ok. It is rated at 2000RPM max. It sucked full pipes of sawdust through the inlet and blew it out the discharge pipe ok, but did open the governer when she sucked up some wet stuff. I have about 80 yards of it to move and it has to be blown into a 10 yard tip truck. I ran equal 6 inch pulleys on both the motor and blower, So it was running at 2000RPM. Is this ok or too quick?? It is an old Richardsons 7 inch Sawdust blower........have only used rated Dawn blowers before......

[Brucer]

How fast was your sawmill shaft turning. I wouldn't want to exceed that.

There's a lot of factors involved in determining the maximum safe speed for a blower. The diameter and weight of the impeller; the shape of the blades; the diameter of the shaft and the bearing spacing.

[submarinesailor]

You'd almost think I used to work in the fan industry ;D.

Why yes we did come in from the shaft end. :D :D :D  And maybe I worked with some of the fans you supplied.  Ever build anything for the steel plants between Gary, IN and Pittsburg.  I think I was just about all of them at one time or other. : : :

Bruce

[Brucer]

I worked for Sheldon's Engineering, a Canadian fan manufacturer Cambridge, Ontario. They had a US subsidiary under the same name but I didn't work on many US jobs. It wasn't a huge company but we made some pretty big fans -- as in 6000 HP ID fans for thermal generating plants. The small commercial stuff you could just fit into the back of a full-size pickup.

[acco1840]

How fast was your sawmill shaft turning. I wouldn't want to exceed that.

There's a lot of factors involved in determining the maximum safe speed for a blower. The diameter and weight of the impeller; the shape of the blades; the diameter of the shaft and the bearing spacing.

ths saw was spinning at 750RPM but the blower had a 5 inch pulley and the mill drive pulley was like 16 inches, so I guess it was running at about 2300 RPM.