15" vacuum

[Maple4444]

I can not turn my used vacuum pump above 15" or the new 3 hp electric motor gets hot and trips breaker. I have been running it for 2 seasons at 15" and ok with it. My question is how much more sap could I or would I be getting at 24"? Just wondering whether it is worth looking into bigger motor and/or rebuilding or replacing vacuum pump.

[BAP]

What is the vacuum pump? Brand and model? What size breaker do you have feeding it? Is the wiring big enough?

[Maple4444]

It is a Sihi 3404 oil cooled single stage. The motor is 220 volt and my electrician ran new wire from panel and sized breaker for 3 hp motor. I am positive wiring and breaker size are not issue. Perhaps this is all the vacuum this pump will achieve.

[Sterling Maple]

I would look online to find the pump curves for that pump. If you could get that vacuum up, you would make a boatload more. I think I recall 10% more sap per inch of vacuum over 20". When you first start, I would close off the releaser and see what the pump has the potential to pull before it has a chance to get hot. After you open up the system to draw from the woods, see how much air is being exhausted. That will tell you if the pump is moving air and if your system is tight enough.

[motowbrowne]

I could be mistaken, but my memory is that to go from no vacuum to 16" you should see a 150% increase in sap yield per tap. Each additional inch over 16 gets you like 4-6% more. Again, just going from memory on that.

[Moser's Maple]

You could try to blow a fan on the motor to see it that will keep it cool enough to go higher. Sounds like it may need a larger motor, but a fan would be a cheap fix to try to combat over heating issue.
Oh almost forgot are you running 110v or 220v to the motor? I would also presume it's a 1 phase motor running in 1 phase power?

[BAP]

A couple of thoughts, I looked up on the SIHI website and found the specs for the pump and it is rated as either a 2hp or 3hp pump so the motor size you have should be fine. You said you have a new motor on it. Did you put it on and is it the same motor that came with it? Is it the correct RPM and the correct style motor. If you are not familiar with electric motors, there is more than HP to rate a motor. RPM's is one variable but also how is rated to be used is another. Not all motors are designed to be used for vacuum pumps. Another thought is even though you had an electrician hook it up, are you certain he used the correct size wire to feed it? Also is there enough power feeding the breaker? If it is undersized the motor will not get enough amperage causing the motor to overheat. I have seen electricians that were not familiar with motors hook them improperly. Another motor item is was it hooked up so the pump is turning in the right direction? Most motors can be wired to turn Clockwise or Counter Clockwise. The last thing to check is the liquid flowing threw the pump. I have only had experience with 1 liquid ring,(the other 6 were vane pumps) and we ran it on water. But I do know that if there was too much water flowing threw the pump it would work too hard and slow down. I am not sure if this is the case with SIHI pumps or not but worth checking out. If everything is operating correctly you should be able to 24-25" easily with that pump without hurting the motor. I hope this helps you trouble shoot and get it working.

[BreezyHill]

I would look at your pulley size on the motor. If you are using to large of a pulley on the motor you will be working the motor to much. Smaller pulley will run the pump slower thus needing less amperage to spin the pump.

In the event that they are sized properly then you need to check your wire connections and test for low voltage. Low voltage will make a motor run hot under a load.

0" to 15" of vac increases production by about 150% and for every inch of vac above the 15" you increase by 3-5% were the numbers from Dr Tim in the past.

so to go from 15 to 24" is a 9" increase so you should see an increase of 27% to 45% in production. I notice in our operation where we try to run a 28" and above we will be producing far more sap than neighboring bushes that are running 20". 35 degree cloudy, still day and we are doing pretty darn well and if the sun comes out you need to have the RO running to keep up.

You will not be the first person that has had a low voltage issue get in the way of progress.

Good Luck!

Ben

[Maple4444]

Thanks for all the advice. I will look further into electrical and draw on motor etc... Pretty sure I have the proper motor because it is a direct drive 3hp rated for 1770 Rpm wired 220 V. I am wondering now based on the previous comments from BAP that perhaps the oil is too "heavy" making the pump difficult to turn.

[BAP]

I don't know what you are running for oil, but it might be as simple as needing to slow down the flow of oil threw the pump. I know with our water ring pump, we had a valve in the feed line to adjust how much was going threw the pump.

[DrTimPerkins]

Each additional inch over 16 gets you like 4-6% more. Again, just going from memory on that.

Close....it is 5-7% more per inch Hg.

[madmapler]

I don't know what you are running for oil, but it might be as simple as needing to slow down the flow of oil threw the pump. I know with our water ring pump, we had a valve in the feed line to adjust how much was going threw the pump.

I was going to say the same thing. My sihi runs with water and you have to limit the amount of flow with a valve. If you let it run wide open the amp draw increases by as much as 10 amps. It's a 10 hp motor. I look at the amp draw on my VFD and keep an eye on the Vac. guage. You don't need to see the amp draw though. Just cut it back to where you see the vac. starting to drop then add a little. That pump should do 24-25 " on a tight system provided you don't have too many taps on it.

[Maple4444]

Thanks again guys. Found ball valve for oil on inlet side before it goes through a radiator/ cooling fan assembly. I closed it off a bit and Turned pump up to 20". I will play with it later to see if I can get 24"

[BAP]

If you don't have a VFD on the pump, get a Amp meter to check the draw and adjust it. An electrician should have one of the ones that clamp around the wire to measure. Then play with the oil flow and vacuum levels to see how it effects the amperage drawn. The plate on the motor should say what the motor is rated for on the amperage. If the pump works fine at 15" and overheats at higher vacuum I would tend to think that it is drawing in to much oil causing it to work too hard.

[BAP]

Did you get your pump going?

[Maple4444]

Did you get your pump going?

Hi BAP. I missed your question in this thread. Yes I did get my pump going. By restricting the oil slightly I comfortably ran at 23-24" of vacuum. Thanks for your help.

[BAP]

Glad it was a simple fix and it worked for you.