Delaval 78 vacuum pump - too big?

[S Wright]

A friend of mine recently cleared out his father-in-law's old dairy equipment to make room for other ventures at their farm. I couldn't compete with the Amish guy who took the milk tank, but he left the vacuum pump and my friend asked if I might be interested in that. It is a Delaval 78, and it is still in running condition. They haven't milked for a number of years, but he said his father-in-law ran it once a week until recently because there was some sort of annexation issue going on in their area, and they were essentially running it periodically so that if they were annexed by the city and decided to get back into dairy, they couldn't get blocked for increased noise or whatever. Something like that, I don't know. Anyway, we just finished our 3rd season, 2nd with an actual evaporator, and we're planning to continue to expand. We did 204 taps this year, and took an inventory of our woods last summer, which found about 730 potential taps. There's also another 12-15 acres of woods that is adjacent to mine that we're hoping to eventually buy or at least potentially lease, so in the long run we may end up in the 1500-2000 tap range. For next year though, probably around 400.

I don't know much of anything about vacuum systems, but I have read a bit on here and have seen the rules of thumb of 1-1.5 CFM per 100 taps. From my brief research of the D 78, it appears that with a 5HP motor it does something like 60 CFM? I am just wondering whether the D 78 would just be way too big to use for our relatively small operation? Or if the price is right, is there such a thing as "too big" for a vacuum system? I have seen a lot of talk on the forum about the D 73, 75 and 76 but only a couple references to the 78.

Last question, does anyone have any idea what something like this would be worth? He didn't give me any sort of asking price, so I'll have to make him an offer, and I really have no frame of reference for what is reasonable. I don't want to overpay, we are already investing a ton into our sugarhouse and a bigger evaporator so we weren't really ready to go to vacuum yet, but I also want to be fair and not just lowball him.

[BreezyHill]

You will be fine with that pump on a small or medium operation. To large is a mater of the elec bill. It will cost more to run a 5 Hp without the need but it should only pull the amps that it needs to produce the vac level you desire or require of it. This is a perfect location for a VFD in the future.

This season I found the max tap count for a D73 is less than 750 but more than 600. 73 was the standy by unit for my D 75 that went down when it plugged the oil lines after a helper added the wrong oil into the pump. So the 73 got plugged in for a while. She did good but could only keep the gauge at 22 during peak flow and would go up to 25 when flow was slower. 75 would pull the system to 27 in a little over a minute and just sit and run. Your unit will pull a system for 200 to vac level in a mater of under a minute. Heck it would pull my current system in about a minute or so and I have around 6000' of 1 inch mains.

The other issue a large unit will give you is it will be harder to realize you have a leak. You could have a drop or two pop off and not even see a drop at the gauge. You would see the affects in the mains flowing faster but plenty of reserve CFMs to handle the problem. Good issue not a bad one though.

he price advantage of a used unit out ways the cost of a smaller new unit or the cost that can be associated with a used unknown pump. Nothing worse than a used pump that suddenly fails and is costly to repair. This unit parts are available for rebuild or just a simple update of the bearings and the vanes if they need it.

Price will vary a lot. I have gotten similar units in Surge models for as little as $100 and seen them go for as much as $850. Both in working order and running fine. If it had a reclaimer on it, would be worth more toward the upper end. The $100 unit had reclaimer and good motor...was missing a 5" plastic line to a dripper but I only run copper so it had to be replaced anyway. Plastic can melt way to easily and cause costly repairs.

IMO offer him a cash amount and something you have access to annually...syrup. If you offered $250 and a gallon for the next five years; he has green backs in hand and a product to enjoy longer than the cash will last.

I find that paying for little things with friends in syrup is enjoyed by the family of the friend way more than cash. Especially if they have kids. "Is there anything my dad can do cause we are out of syrup." Will get you a little yard helper pretty quick or at least a little buddy for life, if you slip him a pint.

The old art of barter isn't lost yet...but it needs a revival effort to help keep some of our farmers a float.

If he still has the releaser system grab that too!

Besides when you go to vac you will have more syrup to pay him more if you desire.

Good Luck with your great find!

Ben

[S Wright]

Thanks for all the info, Ben! It sounds like I probably should go ahead and jump on it as long as he isn't wanting a super high price for it. Funny you mention bartering, he actually asked me a few weeks ago if I'd be interested in working out some sort of barter arrangement for syrup since they do a lot of produce for farmer's markets as well as raise pastured poultry. I think we're going to trade some syrup for butchered hens, but that's a good idea to work some into the vacuum deal.

I've got one other question regarding the pump and the motor sizing. Would it be possible to just put a smaller motor on it if I'm not needing as much CFM? We have quite a few little motors around the farm, I could probably round up a 3HP motor to swap out. I don't know though if it would make much difference, like you said, if there's less load on the motor, it isn't going to pull the max amperage. I feel dumb having to ask about this stuff, I am a mechanical engineer for a custom industrial lift company, so I size hydraulic pumps and motors all the time. I just designed an entire 14klb electric vehicle last year with 10+ mile range, but I've never worked with vacuum systems, and my approach when working with new things has always been to assume I am ignorant and ask a lot of questions. Otherwise, you can get yourself into a lot of trouble if you assume you understand something new just because it looks vaguely similar to something you already understand.

[BreezyHill]

Good question. In theory there would be a small savings in elec with a smaller motor as there is a small amount of elec that is needed to spin a motor. The larger the motor the more watts this is...but is it going to be as much value as the time to change the motor???

Funny world we live in. Droppin off feed at a customer and they flag down a neighbor that heard of me and want to see if I wanted his bulk tanks and vac pump. Theives stole the tank tops and some of the stainless pipe then we walk to a back room in the barn and he pulls down a sheet of plywood and there sits a bright blue D 78. He has to take the offer back to his brother but he is fairly sure its a deal.

This one has a 7.5 motor on it. On Tuesday I was at another customer and saw his vfd driven vac pump...running 13.5" at 4.3 amps on a 10 hp motor.

So I am leaning toward don't change the motor more now than ever. If it would run on less Hp then that would be the way to go to save $$$ on a vfd in the future. Smaller vfds are much cheaper than large ones...by a lot from what I have looked into.

by the way I offered $350 without motor and $450 with.

Barter is always a good thing for both parties I have found.

Ask the questions...guy told me a few days ago...too many questions go thru pms and many don't see the question or the answer and miss out.

Ben

[S Wright]

It sure is bizarre the way things work like that, strange enough to get offered an old Delaval pump when talking about pumps, but even more strange that it was the more obscure one that I was asking about!

Makes sense that there'd be such an efficiency difference using a VFD. I probably spent close to two months tuning the parameters to control the drive system in the electric vehicle I mentioned in my earlier post, and I would have liked to have done even more but it had to ship by the end of the year to get paid. Even just seemingly tiny little tweaks could make the difference between the thing throwing undervoltage/overcurrent codes or overheating within a short distance vs being able to cruise along for 10+ mile. They had tried to do the same thing almost 15 years earlier without any type of sophisticated controller, and by all accounts it was a miserable failure.

Thanks again for all the input, Ben. And also thanks for letting me know what you offered the guy, that helps give me some frame of reference to base an offer around.