New guy with "msd" flow bench...problems

[rangergt]

Hi I'm new here my name is Paul. I built a "msd" flow bench 16 years ago and I was never really happy with it. I never found it to be accurate, maybe something I did but I do think the plans are quite flawed. Well I haven't used it in years and I'm now getting back to doing some serious work with it. Finding this site was great, I know I'm in the right place.

A couple of details about my bench, I have dwyer 38" u tube manometer and a 6" incline manometer. It also has 6 ametec motors rated at 110cfm each. Since I haven't used the bench in some time I did a leakage test and well it's not good. No matter what orfice size I'm on it pulls 34" h2o (with flow control valves closed)and and measures .7" flow, which if my calculations are correct it's 34.15% leakage . I really have no idea where it's leaking that bad from because when I built it I sealed it up like crazy but maybe things have just dried out over time.

My thought is that I'll pull it apart and salvage what I can and get the plans to build a PTS flow bench because I want something accurate and repeatable. I'd like to feel confident when I talk results of flow numbers from my bench that their accurate and not inflated.

[1960FL]

Paul,

Welcome aboard and before you jump ship on your MSD bench and start another project, you may be able to make some simple modifications to the bench and begin your quest.

Please don’t get me wrong I am a huge proponent of the PTS/FBT bench but I am also a realist when it comes to other peoples projects as I know I can’t even think of getting all mine done.

My thought is if you could post some picks of your bench and then think about what it would take to do the following.

One, remove the rotating disk and replace with Bruce’s sharp edge plates, this will require you to seal off the slot and shaft holes and add a deck plate to the front for orifice changes. Then begin your leak testing again see how it looks and if all is good move on to calibration. There are many of the MSD benches out there and along with the SF benches use the disk, they leak and based on the design have issues with air flow orientation to the orifice but I think this simple test for a net cost under $100 bucks will get you flowing. Then everything you buy will be needed on your PTS/FBT bench if you choose to build one.

Last please remember the PTS/FBT bench does not need to be digital, I would love to see a build using your existing water gauges. IF you choose to go the PTS/FBT way you have a good start with motors and gauges and you will only need two more motors and the motor controller to complete your build.

Post some pictures.

Rick

[rangergt]

Thanks Rick, I like your ideas, so I'll try them out first before I decide to move on with a new bench. I'll have to take some pictures to post.

If I do decide to build a new PTS flow bench I would use my manometers since they are good quality and it would be a waste not to use them, plus it saves me money for other flowbench tools and accessories.

[rangergt]

So i have some pictures of my bench showing most of all the details including where I located the brass tubes that hook up to the 6" inclined manometer (that was tough). So I am going to go ahead with the suggestions Rick made and with the bench in upgrade mode I may add a couple of extra motors right now. I'm also open to any suggestion to improve what I have. I'm not concerned about it turning into a frankenstien bench since it isn't that pretty any way. I'm just after function accuracy and repeatability.

Should I install the pressure taps instead of the brass tubes and is there a better location than I have them now.

I know I'm getting ahead of myself here but since I'm going to order some parts, I'd like to get everything I need the first time. I'm going order the orfice plates, so when it comes time to calibrate the bench do you use one of the unused orfice plates over the flow bench inlet? I'm just trying to understand this, thanks.

Paul

[rangergt]

more

[Brucepts]

Check this post out from the old forum, about halfway down the first page, LarryC's mods

http://www.tractorsport.com/forum/viewt ... &hilit=msd

No pics just the text remains for right now.

[1960FL]

I wll look tonight to see if i can find Larry's pics and post them.

[rangergt]

Thanks for the info Bruce, that helped a lot. Now if I'm understanding correctly LarryC made his own orfice plate for inside the bench (so it could be of unknown flow value) and then used your PAP plates on the top opening to claibrate the bench from there to determine what the actual flow of his orfice plate was.

I do like the idea of being able to change the orfice plate just in case, I always like to leave the option to grow. So I will likely do the deck plate in the front of the bench to change orfices.

Another question about the PAP plates, they are rated for flow at 16" correct? If I'm using them in my bench with is not digital, I'm using manometers and when my test pressure is set to 28" what is going to be the result? Is there going to be an error or do you have a clibration correction for that? I may have read this but this site is great with so much info and I've been doing a lot of reading, so it's kind of like being in a fight with Mike Tyson being hit from every angle and can't focus lol.

One other upgrade I will add is another manometer for velocity probing.

Pictures would be greatly appreciated if possible but if you can't find then I'm sure I'll make it through. I can always post pictures of my modification before I make them final and get some opinions.

[1960FL]

I would get with Bruce to configure a couple of internal plates to give you range, He can do the flow math for you on these plates for your DP at 16" if you chose to go PTSDM and 28" for on top of the bench. Its all just math.

Rick

[rangergt]

That's what I'll do. I did reread some post and I'm getting more familiar with some of the info. Being away from using the flowbench for so long, it takes a little bit to refamiliarize myself with what little I did know.

On a good note, When I tested my leakage I found that one of the ends to the inclinded manometer had become disconnected after the fact. Then the bench was unuseable, when I figured out what was wrong I forgot to retest the leakage. I just retested it and I had 0% if that's possible, even at 36". So that is one problem eliminated.