armstrong/baldor update

[burner1941]

Jake told me Aug 14,

Burner,

I can't speak as to the pump but I am very certain... from personal experience dating back twenty years to this date... that Baldor engineers, manufactures and ships some of the best motors around.

I don't deal in the little motors much, but I'd suspect they are also very good quality.

If your question is for Baldor, just call their main office at (479)

646-4711 and ask for a support engineer. They're friendly and honest people... and they'll be eager to help.

In my experience... about 90% of new motor failures are due to overloading conditions presented by whatever the motor is coupled to...

or incorrect coupling (misalignment or belts too tight). Closely-coupled pumps with bad or leaking seals will fail motor bearings very quickly.

Jake

Jake looks like this problem falls in the 10% range of your evaluation. This Armstrong pump was brand new and the problem started at start of operation.

The Baldor motor was tested by motor repair shop, and determined faulty "weak" and a new motor was obtained from Baldor and the results were the same. Baldor requested both motors to be shipped back for evaluations. Their evaluation determined that they were good. They wouldn't test with a more comprehensive dynamic test, because of cost, and pointed us to Armstrong Co. Meanwhile what do we do, each are pointing the finger at each other?

So luckily the pump we replace was identical to the replacement. I had the motor repair shop rebuilt this old pump, also when disassembling check the old impellar, in order to determine if the impellar was exactly the same as the new, it was. The motor shop called Baldor, and with this news they decided to test the motors. Lo and behold both tested "bad" so they are going to ship a new motor.

So my hope is that they will get it repaired before heat is needed, because the customer doesn't trust the new pump and want the remaining warranty time in operation. Meanwhile I'm supposed to be happy with the results. Somehow I'm thinking aggrogant bastards.

Burner

[Jake]

Thanks for the update... but I have a hard time understanding the sequence of events here...

Was it like this:

A pump failed. A motor shop called the motor "weak", installed a new one with the same result... no working pump. The motors were sent back to Baldor, where they did static testing (probably severe insulation testing). Baldor called the motors OK.

So.. you had a new pump... and you had a motor shop rebuild the old one.. checking for impeller differences. None were found. The motor shop contacted Baldor again.. Somebody (who?) tested the motors again and called them bad this time?

My thoughts:

Motors cannot be deemed 'weak' by most any reputable motor shop I've ever dealt with... by dynamic testing... it takes a dyno that many don't have. If the insulation tests OK, and there isn't very obvious rotor or bearing damage... my experience 100 percent of the time is that the motor can deliver the rated horsepower to the shaft for its rated duty cycle.

I would seriously question a shop that deemed a motor 'weak' without very substantial dyno evidence proving the fact.

Observations: If the first identical pump ran for a time without difficulty, I'd suspect something has changed in the pumping system that has caused pump overloading. In larger centrifugal pumps, it's usually related to lowered head pressure on the discharge... particularly at startup. A failed check valve (either open or closed, depending on the setup) can cause this. Severe discharge flow downstream may also cause overloading.

If the plumbing system cannot be remedied, what Paul suggests is common (if not accepted engineering) practice... upsize the motor HP a little. On some centrifugals, impeller clearance can also be adjusted for different flow rates... which also affects motor loading.

Also... be sure that the pump is rotating in the proper direction... this is a biggie that confuses a lot of people. Many pumps will still develop pressure operating backwards.. it just takes more energy.

Just my tiny thoughts!

Jake

burner1941 wrote:

[-zero]

The last time I've come across this, it turned out to be pump cavitation. An old hotel on the beach with a 1950's boiler room. What a place! A bigger motor may make this worse. The pump was sized to the x-changer, but no one bothered to draw out the system, and doodle up a system curve. I find a pile (ok, 4) newish motors on the floor, all bad. A new impeller, bearing assembly, still they only worked for a day, a week maybe.

With gauges on the pump, in this instance, there was 12psig off-pressure with on-inlet pressure dropping to 6ish and outlet to 17ish. As the tank approached set temp (140°f), and the pump inlet gradually increased. (180° boiler supply water> heat-X>pump>boiler return) the pump would go into cavitation. The no-money-making fix was to increase the system pressure to

19 psig. The system (oversized expansion tanks) took the pressure just fine, with the pump inlet never dropping below 10 psig.

You really need to add a couple of gauges (1 on the inlet, and 1 on outlet flange) and record the system-off pressure and the system-on differential pressure. Then the quasi-system curve can cross against the pump curve to see what may be happening. If you have any valve movements (3-way, etc. vs. on-off control), you need to log those also in there respecting positions.

If you post the pump info and the readings, I'm willing to have a look see.

-zero

[Jake]

Me, too.. a curve can be developed with the total head... and then we'll see.

Jake

[-zero]

Alrighty then! We're good to go! 8-)

-zero

[burner1941]

snipped

Let me start from the start. A 12 to 14 year old 1 1/2 horse Armstrong pump showed some signs of leaking at the seal, this past November. Since it was the primary pump [no spare] a new pump was ordered, a identical match. The new pump came in December, and and the old one finally locked up. The new one was installed in Jamuary.

the starter overloads after a few minutes of operation. Balancing valve was almost turned compelety off to keep it running [the new pump], however the amount of water was insufficient, to keep the boiler from tripping on the manual reset limit. I should say It may run a week or sometimes just a day or two, it was babysitted until the heating season was over.

Talking to an engineer from Armstrong, and he called it a "weak" motor. I took it to an approved Armstrong repair place, sometime in June.

They have a testing ability, that actually has a pump under load pumping water. The repair place determined the same thing I discovered. They called Baldor and had a new motor sent and upon installation it did the same thing, overload whenever any load what so ever was placed on it. Baldor requested both motors to be returned for evaluation, and they said the motors checked OK, however they wouldn't perform a dynamic test because of the cost, otherwords they couldn't believe they manufactured two bad motors.

It seems I always had to get the answers by waiting a few weeks, [I realize everyone is slow] I'd call the repair shop and he'd get busy to come up with the answers no one ever followed through, without prodding.

So since I'm up a shit creek with Armstrong saying its the motor and Baldor saying is the Armstrong pump. I had the original pump repaired, so they could determine if it had identical parts. It did. Armed with this knowledge the repair shop could go after the most logical one, Baldor. Baldor then performed their so called expensive test, and declared both motor were defective, and as of yesterday, they are suppose to send another motor. The repair shop requested they test it before sending.

My original post here was to see if anyone else had experienced any problems. It's hard to believe with the time span, I'd get two defective motors. Hopefully this is a clear picture of my experience with this shit job.

I kinda think they had the wrong nameplates, probably smaller horsepower motors. It ran a long time for it to be bad insulation. I doubt I'll know for sure.

Burner

[AKS]

Wrong nameplates that is very possible, however I would check voltage and current which I am sure you did, "also" if motor is actually 60 cycle rating if happens to be 50 it will definitely under load trip.

60 cycle motor to run on 50 cycle you most reduce voltage by apx. 10%. 50 cycle motor to run on 60 cycle you most increase voltage by apx. 10%. good luck DIDO

probably smaller

[Jake]

Burner,

Thanks again for the info.

One more question to clarify things for me...

Are you saying Baldor did static testing... called the motors good... and then they retested dynamically and called them bad... the same motors without any further use between testing?

Did they say WHY they were bad?

I doubt these things had the nameplates wrong... I really do.

Do us a favor and post the Armstrong Model #,and the Baldor catalog or spec. number.

We'll help you get to the bottom of this....

Jake

[burner1941]

Don't know what kind of 1st test Baldor did, but declared them good, but wouldn't do a more expensive test, [whatever that is]. When the repair guy told them the old pump had identical impellar with same horsepower motor, [forgot brand think is was US something] Then Baldor agreed to do the more expensive test on the original new motors and the replacement they had sent. Same motors, that had been in their hands for several weeks. After this test was performed they said they were bad, but not any reason yet. I've asked but nothing yet.

No

This motor ran from January thru May, with several resettings, but it ran constantly enough to provide heat. How could insulation be bad, and not cause a failure before this time. If so looks like their first test would have revealed different resistance than the norm.

I know this isn't lab type answers, but the Armstrong balancing valve had 4 rings exposed on the valve shaft. To keep the new pump running, I closed the valve and opened it to approximately 1/2 to the 1st ring. A quarter turn would sent the amperage wild. The repair shop did the same with their test stand. When a load was just started it would overload immediately. However the old repaired pump, ran like a champ, this news encouraged Baldor to do the second test.

Do us a favor and post the Armstrong Model #,and the Baldor catalog or

Both Armstrongs pumps are model# 3X3X64280 3 phase 230 volt. Don't have anything on Baldor yet. The repair shop has just receive the new motor, today. The old pump has a different brand motor, but same horsepower.

What I'd like to do is get Armstrong to start the one year warranty over again, with all this hassle. My customer isn't pleased and doesn't trust it. That's why I'd like to reinstall the new pump, to get the remainder of the warranty. The repair shop has agreed to start the warrant of his repair, of the old one, when we install it, maybe next year. The need of heat here in Ohio is probably going to be needed by next week. Meanwhile we are moving into the 11th hour.

Burner