Announcement

Collapse
No announcement yet.

What are your DC CFM's

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • #31

    Re: What are your DC CFM's

    Re: What are your DC CFM's

    Originally posted by beckerkumm View Post
    The CV 1800 was designed for a minimum of 1000 cfm through 6" pipe. John, your example shows how the resistance of 6" drops the cfm over distance. Every gate leaks a little too so that affects the numbers. Dave
    Dave, it would be interesting to see how much the CFM would drop in a 65' run of 6" straight pipe. Unfortunately my run has too many turns but does a good job collecting dust from my miter saw station. I recently changed the CV1800 for a Felder RL 160 and want to get some readings from it this winter if time allows. Should make for a good comparison.

    John

    Comment

    • Thread Continues Below...

    • #32

      Re: What are your DC CFM's

      Re: What are your DC CFM's

      Originally posted by John JMK View Post
      Dave, it would be interesting to see how much the CFM would drop in a 65' run of 6" straight pipe. Unfortunately my run has too many turns but does a good job collecting dust from my miter saw station. I recently changed the CV1800 for a Felder RL 160 and want to get some readings from it this winter if time allows. Should make for a good comparison.

      John

      John,

      You should have a fun curve for your Felder unit. They do not appear to have one readily available. I have attached the curves for the CV 1800. The CV Max values are not accurate due to some testing issues for the larger unit. I wish these guys would just edit out what is not supportable. But at least there is a curve for the CV1800. Oneida and Grizzly publish their curves.
      My limited understanding of all of this is you want a good idea of what your system will do in your service conditions. According to Pentz' static calculator, your 65 ft of 6" of straight will cost you 4.41" WC, ea 90 degree = 0.76" and each foot of flex hose = 0.20".
      If my curve is accurate, I should see 1000 CFM @ 12" WC loss, if I have an Oneida V-5000, I should have 1000 CFM @ 8" WC, a Grizzly G0442/G0601 should give 1000 CFM @ 11-12" WC loss. The Grizzly is based on a 10" inlet, so needs some adjusting.

      I am sure you are up on all of this, but just in case. Without the Felder curve, or any fan curve, you are guessing because you cannot duplicate the test conditions. IMHO

      Don

      Clear Vue Fan Curve-1.pdf

      Comment


      • #33

        Re: What are your DC CFM's

        Re: What are your DC CFM's

        Thanx Don, I also have read Bill's info quite intensively though it was in 2008 with occasional refreshers. I can only give my observations between the 2 units based on my short time with the RL 160. The first most obvious is that the RL 160 is not a cyclone but after having seasoned the filters the suction appears to be marginally better. This could be because I had to relocate it my shop and overall have reduced the distance to various machines. The main reason for the upgrade was capacity of the bins with an effective bagging system and buying machinery for the write off. An added bonus is that its also much quieter. I have found the performance curve in the manual if you are interested but don't want to hijack Matt's post unless he is also finding the info useful.

        John

        Comment


        • #34

          Re: What are your DC CFM's

          Re: What are your DC CFM's

          John, I hope you publish your RL numbers. I agree it is the bends that really cost although velocity increases resistance in straight pipe so as you increase the impeller size to speed up the velocity you also add SP so it becomes an issue of diminishing returns. I don't believe any of the published system curves. Too much ability to juice the numbers. Put a bellmouth opening on various lengths of pipe, leave off the filters, add a filter, etc. At the end of the day, any cyclone with filters with less than a 14" impeller and 3 hp motor is not a good value for the money spent. Matt's large impeller performs very well with the 6" pipe. Were he to use the 8" that is more standard with a 5 hp motor, I have to think he would overamp his motor. Dave

          Comment


          • #35

            Re: What are your DC CFM's

            Re: What are your DC CFM's

            Dave, another thing my fan has very little clearance so it almost works like a pump. I think it's called Gore, the plan blades only have 3/8 clearance here. I believe it was supposed to be 1 inch. My fan being 17 1/4 inches is in the Bill Pentz design for a 16 inch fan. The backplate has a quarter inch clearance and a quarter inch clearance from the blades (on entry side) to the housing. This is probably why my cyclone might be a little louder than most.
            For every action there is an equal and opposite reaction.
            Sir Isaac Newton.

            Comment


            • #36

              Re: What are your DC CFM's

              Re: What are your DC CFM's

              Originally posted by beckerkumm View Post
              John, I hope you publish your RL numbers. I agree it is the bends that really cost although velocity increases resistance in straight pipe so as you increase the impeller size to speed up the velocity you also add SP so it becomes an issue of diminishing returns. I don't believe any of the published system curves. Too much ability to juice the numbers. Put a bellmouth opening on various lengths of pipe, leave off the filters, add a filter, etc. At the end of the day, any cyclone with filters with less than a 14" impeller and 3 hp motor is not a good value for the money spent. Matt's large impeller performs very well with the 6" pipe. Were he to use the 8" that is more standard with a 5 hp motor, I have to think he would overamp his motor. Dave
              I think that Matt has made a very good impeller and agree that 8" unrestricted may overamp the motor but in actual use that would be very difficult unless too many blast gates were open at once. I like the use of 6" pipe mainly as cost consideration and my experience has been it delivers great dust collection as I'm sure you have found. I'm interested to see Matt numbers when he has his system fully installed and hooked up to the machines, I think it will be very efficent. To address fan curves and cfm ratings, like you have stated they have been abused by the big sellers of small shop dust collectors as marketing ploys for substandard equipment with mediocre performance. We live in a world of smoke and mirrors, build something that looks like it might work, put a sets of wheels on so you can be portable, make it short for low ceilings and tell people what they want to here. As the saying goes there's a sucker born every minute.

              John

              Comment

              • Thread Continues Below...

              • #37

                Re: What are your DC CFM's

                Re: What are your DC CFM's

                My main takeoff is a 4 x 10 so 40 in.². So ideally anything over 7 inch diameter main would probably be a waste of money. When initially testing cyclone with no ductwork just the intake open the motor was pulling 25 A. My motor is only 23 1/2 amp rated with a 1.15 sf. My initial thought was, I'll never need more than two ports open at a time. So 6" main it was.
                For every action there is an equal and opposite reaction.
                Sir Isaac Newton.

                Comment


                • #38

                  Re: What are your DC CFM's

                  Re: What are your DC CFM's

                  Matt, you are, like me, compensating for small pipe with a large impeller. Your design does better than i would have expected so you have hit the sweet spot. When running fairly new Euro machines which are pretty efficient from a DC standpoint, I can see where a 6" main can work, but only with a large impeller. My old iron jointers, planers, and particularly edge sander, need everything a 7" to 8" main can handle. The old machines are a joy to use but need about twice the cfm as the newer Euro. Dave

                  Comment


                  • #39

                    Re: What are your DC CFM's

                    Re: What are your DC CFM's

                    So tonight I jerryrigged a manometer together to check the system in complete closed. The manometer is a little confusing to me. I know this checks the vacuum pressure in a close situation. But how is this applicable to CFM? I'm not sure if these are good numbers or not but here they are.
                    Click image for larger version

Name:	image.jpg
Views:	1
Size:	22.0 KB
ID:	907224
                    Red 0 line.
                    Click image for larger version

Name:	image.jpg
Views:	1
Size:	20.3 KB
ID:	907225
                    10" elevated above 0
                    Click image for larger version

Name:	image.jpg
Views:	1
Size:	20.8 KB
ID:	907226
                    20" difference between water levels.

                    If 1 " = 0.036 psi I am getting 0.723 psi. How is this info useful?
                    For every action there is an equal and opposite reaction.
                    Sir Isaac Newton.

                    Comment


                    • #40

                      Re: What are your DC CFM's

                      Re: What are your DC CFM's

                      Matt, what is typically done is the manometer is used to obtain pressure readings at different airflows so you can produce a system curve.

                      I use a manometr to determine when my filter needs cleaning.........Rod
                      Work is the curse of the riding class.

                      Comment

                      Working...
                      X