Questions about March Pumps answered by the Factory!

[uglefisk]

Thank you Walter, replacing the carbon bushing using a vise worked like a charm, now I can finally use these extremely nice pumps again

I used the stainless axle and a flat washer to distributed the pressure while inserting the bushing.

you could do it with a vise at home....only thing i would do if you do it yourself is to make a support fixture for the bushing....what we use here is a spindle that fits the bore hole like the shaft would and with a wide face to support the bushing as its being pressed into the impeller....this way the pressure is distributed evenly across the bushing face and the shaft will help keep the bushing from trying to collapse as its being pressed in....

 

[86turbodsl]

Walter,

Can you recommend a pump very similar to the 809 or whatever pump most of the guys here are using but with 3phase input? I'm thinking about using a single pump on a 3-tier system but think i might want to use VFD control so i can vary the pump speed. I did find some large pumps in the chemical section, but they seemed too large.

Another option would be buy a pump head and mount on an appropriate 3phase standard motor. I'm not opposed to that either.

 

[WalterAtMarchPump]

We unfortunately don't have any small pumps in 3 phase.....problem is the size of the motors when you get into 3 phase.
Smallest pump that starts in 3 phase would be our series 5.5 pumps that can give you 30gpm...
Another option would be to find a PWM (Pulse width modulator)....that's the only driver i know of that can speed control a single phase motor....but they get expensive

 

[86turbodsl]

Ok, if there's no small ones, how linear is flow at lower speeds? Any pump curves? VFD would typically run down to maybe 20-30hz so pump flow at half speed would need to be known. if no info is available, i might look at a pump head and custom machining to a 3phase motor of my choice.

 

[mattd2]

We unfortunately don't have any small pumps in 3 phase.....problem is the size of the motors when you get into 3 phase.
Smallest pump that starts in 3 phase would be our series 5.5 pumps that can give you 30gpm...
Another option would be to find a PWM (Pulse width modulator)....that's the only driver i know of that can speed control a single phase motor....but they get expensive

I have successfully been using a SCR phase angle speed controller (sometimes called a router speed controller) to reduce the flow of my (not March) pump. Can be found for cheap on Ebay. From my research this is the typical way to speed control a PSC motor. Only issue is it is not very linear, and to get down to really low flows the motor is running quite slow and I am concerned that the fan will not be cooling it enough.
Also I have seen some DIY circuits for SCR speed controllers that include EMF feedback to ensure the motor speed stays constant regardless of the load on the motor.

 

[86turbodsl]

But those are not commonly controllable via modbus either.

 

[mattd2]

But those are not commonly controllable via modbus either.

I had no idea you wanted it to be able to be connected to a SCADA. Look into HVAC fan controllers. Usually these are still single phase PSC motors for the smaller sizes - example http://www.aircareautomation.com/text/variphase_v.html

 

[WalterAtMarchPump]

Ok, if there's no small ones, how linear is flow at lower speeds? Any pump curves? VFD would typically run down to maybe 20-30hz so pump flow at half speed would need to be known. if no info is available, i might look at a pump head and custom machining to a 3phase motor of my choice.

We don't get into curves for VFD's as there would potentially be hundreds of different ones depending on where the vfd would be set. And its not linear either for our pumps.....too many variables will affect the output of the pump....pipe size...weight/viscosity of the liquid....head height..etc...

I you want to adapt your own motor i can supply you with the drawings of the motor bracket so you can have it adapted to what you want to use....just email me.

 

[WalterAtMarchPump]

I have successfully been using a SCR phase angle speed controller (sometimes called a router speed controller) to reduce the flow of my (not March) pump. Can be found for cheap on Ebay. From my research this is the typical way to speed control a PSC motor. Only issue is it is not very linear, and to get down to really low flows the motor is running quite slow and I am concerned that the fan will not be cooling it enough.
Also I have seen some DIY circuits for SCR speed controllers that include EMF feedback to ensure the motor speed stays constant regardless of the load on the motor.

Well as you have come to find out....the slower the motor turns it wont cool itself off as well and can potentially overheat....i guess you could add a small fan from a PC or something along those lines to help with cooling.

Also the other issue (and im not sure if this would be an issue) but these are not PSC type motors (Permanent Split Capacitor) if you were to take this motor apart you will find there are no capacitors inside....no primary/secondary winding....and no centrifugal switch like a typical PSC motor would have.
These guys are more on the line of a shaded pole motor.
I "believe" (and i could be wrong on this) they are classified as a polyphase motor or a single phase two pole motor....

 

[mattd2]

Well as you have come to find out....the slower the motor turns it wont cool itself off as well and can potentially overheat....i guess you could add a small fan from a PC or something along those lines to help with cooling.

Also the other issue (and im not sure if this would be an issue) but these are not PSC type motors (Permanent Split Capacitor) if you were to take this motor apart you will find there are no capacitors inside....no primary/secondary winding....and no centrifugal switch like a typical PSC motor would have.
These guys are more on the line of a shaded pole motor.
I "believe" (and i could be wrong on this) they are classified as a polyphase motor or a single phase two pole motor....

Yeah I was expecting the need for additional cooling at slow speeds similar to retrofitting a VSD to a DOL industrial motor will require an additional cooling fan.
I have avoided that by not reducing the speed below the point the motor is still getting airflow from the standard fan. But this limits me to not getting below 30% flow (roughly).
my understanding (but don't quote me) is phase angle control (TRIAC /SCR) will work with shaded pole motors as it is pretty much a different method for the same result - two windings with a slight phase shift from a single phase.
As I mentioned I'm not actually running a March 8** with this, rather a Iwaki knock-off.

 

[WalterAtMarchPump]

Yeah i dont know enough about that to say one way or the other...but if it works then go for it

 

[broadbill]

Another question for Walter:

I have my march pump plumbed directly to a CFC for a CB20 setup:

https://www.homebrewtalk.com/showpost.php?p=1476607&postcount=3

I've run it a few times; and I get intermittent squeaks and it loses its prime. There are a number of factors working against me in this setup: the fact that the outlet of the kettle and the inlet of the pump are on the same plane; there are some loops in tubing in the plumbing; also the outlet valve controlling pump flow is located on the on the outlet side of the CFC and not directly next to the pump outlet. That being said; I really like this setup as I can just carry the unit around where I need it and plug it in (I use it for both my small electric and 10 gallon propane system).

Any hints on how to optimize this setup to prevent the pump from squeaking/losing prime? Also, would the intermittent squeaking be caused by a missing thrust washer? I'll be honest, I don't recall seeing one the last time I pulled it apart.

Any help would be great!

 

[WalterAtMarchPump]

Wow that's cool...i've never seen anything like that before. I must say you guys get crafty

Besides opening up the pump to verify that the thrust washer is there, the only thing i can tell you to possibly change to help things would be to get a wooden block and raise the pump up enough to rotate the pump head so your inlet is at the bottom and outlet on top...that will help any air pass through the pump as easily as possible....other then that try and straighten out you inlet hoses as much as possible so not to trap any air in the high spots...everything else looks ok to me

 

[broadbill]

Wow that's cool...i've never seen anything like that before. I must say you guys get crafty

Besides opening up the pump to verify that the thrust washer is there, the only thing i can tell you to possibly change to help things would be to get a wooden block and raise the pump up enough to rotate the pump head so your inlet is at the bottom and outlet on top...that will help any air pass through the pump as easily as possible....other then that try and straighten out you inlet hoses as much as possible so not to trap any air in the high spots...everything else looks ok to me

Thanks for the prompt reply. I like the idea of putting a block at the bottom so I can reorient the head for outlet=up, but then that would mean a significant high spot in the tubing from the pump outlet to the inlet of the chiller, and I'm not sure I could get it all to fit in the bucket.

I will play with it some more. Thanks again!

 

[WalterAtMarchPump]

put a block in there just high enough to fit the orientation of the pump head so the outlet is pointing straight up at your face....put a 90* elbow on the inlet so its easier to plumb.....then you can add a "T" fitting on the outlet.....the side port goes to your chiller lines....the top port you can install a valve so you can easier purge the air out and your in business

 

[broadbill]

put a block in there just high enough to fit the orientation of the pump head so the outlet is pointing straight up at your face....put a 90* elbow on the inlet so its easier to plumb.....then you can add a "T" fitting on the outlet.....the side port goes to your chiller lines....the top port you can install a valve so you can easier purge the air out and your in business

Just as a follow up: I finally pulled that pump in bucket assembly apart to look for the thrust washer. Found this:

Any idea what would have caused this? The washer looks thinned out and broken down.

 

[30Bones]

I can't see the pic but mine was worn paper thin. Replaced it with a ss center inlet head and it's flawless once again

 

[broadbill]

I can't see the pic but mine was worn paper thin. Replaced it with a ss center inlet head and it's flawless once again

Yeah, I didn't have time to mess around with the pic when I posted-but yeah, my washer is thinned down and paper-thin. Is this normal for this type of head? Should I consider this a consumable part?

 

[30Bones]

Yeah its a wear item, but my pump is over 10 years old and that's the original head to my knowledge.

 

[WalterAtMarchPump]

the washer can be considered a wear item but it depends on how its used....the reason it wears is because the impeller is getting sucked up against it....usually from a lack of fluid on the inlet side....like the piping being too small or too many 90*'s in the system, or a valve thats smaller on the ID then the tubing is.....something is restricting the liquid coming in. The pump will still work but instead of i being a transfer pump it has become a suction pump and mag-drives dont like that