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Effect on motor of removing filters

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  • M.McKenna
    replied
    Re: Effect on motor of removing filters

    Originally posted by Bob just past Ayr View Post
    Remember to allow 1sq ft of inlet area for every 1000 cfm exhausted. This means the air would be coming in at 1000 ft/min. If you don't allow for air to come in some will find it's own way, around doors and windows , down chimneys, in sewer vents the list goes on or the fan simply won't move the air it is rated at. If you don't think this is so try drinking out of a bottle and not let any air in.
    Good point Bob, that is what the HVAC guys call make up air. My buddy's automotive paint booth has a gas fired heater to make sure his make up air is the right temp for the product being applied.

    My shop has a few leaky spots where you can feel the make up air being drawn in...
    Gave some thought to running a pipe directly to my planer that would supply outdoor air directly to the source. Decided against it as I thought there would be considerable condensation introduced directly to the planer castings, bearings etc. Any thoughts?

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  • Bob just past Ayr
    replied
    Re: Effect on motor of removing filters

    Remember to allow 1sq ft of inlet area for every 1000 cfm exhausted. This means the air would be coming in at 1000 ft/min. If you don't allow for air to come in some will find it's own way, around doors and windows , down chimneys, in sewer vents the list goes on or the fan simply won't move the air it is rated at. If you don't think this is so try drinking out of a bottle and not let any air in.

    Leave a comment:


  • M.McKenna
    replied
    Re: Effect on motor of removing filters

    Welcome to the forum Mike.

    I don't think you are going to have a problem as there is a load created by the friction loss on the intake side.
    My DC vents directly into the cyclone which is located over the saw dust trailer, no filters. This would be very similar resistance to your Fien baffle. The blower should be able to handle the bits hitting the impeller, even at 90 mph, but it sounds better if they don't.

    I think you will see a significant difference without filters but you will likely max out at 300-400 cfm per horsepower. One less item to maintain too.

    What Matt is saying makes a lot of sense. All the more reason to have a Carbon Monoxide, CO, detector in the home.

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  • mmesford
    replied
    Re: Effect on motor of removing filters

    Thanks for the responses (and for the welcome!).

    I like the idea of the baffle because it should reduce the amount of dust going outside by quite a bit. I'm next to a park/greenbelt so no neighbors. But I also have a heat pump on the same side of the shop as the discharge. Also, I think,the baffle will help reduce bits hitting the blower blades.

    There are no gas appliances to worry about. Only a small electric heater. I've thought about putting in a tiny, yacht-sized wood stove but that may never come to fruition.

    As for the motor load, I will run some load tests before mounting the blower in its new configuration. If it's close to nameplate I'll go for it. If I burn up the motor then I'll have an excuse to build a new system from the ground up. ;)

    Mike

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  • Matt Matt
    replied
    Re: Effect on motor of removing filters

    I would think it would be absolutely amazing to vent outside BUT, there's always one little tiny precaution that has to be taken into account. If you have any natural gas or propane burning appliances that are venting to the outside that are not considered high-efficiency and are in the same enclosed building (or even adjacent with a door i.e. an attached garage ) you will suck in carbon monoxide into the building (home) to replace the exhaust air. This is always a precaution that DC owners face trying to vent to the outside. So please be pre-cautious with heating sources and hot water tanks that use natural gas or propane. Even a simple wood fireplace has a natural draft you could suck the smoke into the home while burning (Possibly you could even overpower an airtight). Just something to think about.

    Edit; welcome to the forum.
    Last edited by Matt Matt; 12-29-2014, 12:11 AM.

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  • Don Burch
    replied
    Re: Effect on motor of removing filters

    You may increase the load as the filters add back pressure, reducing the cfm. You can also remove the baffle as it only attempts to reduce the amount of particulate going into the filters. You have no filters, so you can put all of the dirty air outside.
    Make sure you are not going annoy anyone near by with the extra noise and dust pollution.
    You may find your motor overheating as it will be doing more work.

    Don


    Sent from my iPad using Tapatalk

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  • beckerkumm
    replied
    Re: Effect on motor of removing filters

    Taking off the filters should increase the cfm and also the amp draw on the motor. I'd test the amps with the gates open to verify it is within the nameplate full load. Dave

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  • mmesford
    started a topic Effect on motor of removing filters

    Effect on motor of removing filters

    I've decided to route my dust collector discharge directly outside with no filters. I have a Thien baffle in the suction side and don't expect much dust coming out. (I also don't do a lot of power tool woodworking). My concern is the effect on motor load. Will the decreased discharge head affect the load? I assume it will lessen it but these things are often counter-intuitive. Any thoughts?
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