Max taps on a Gast pump?

[whalems]

What is the maximum number of taps you would run on a Gast 2565v2a vac pump? I have some room for expansion and want a pump that can handle it but don't want to break the bank to do it. so lets hear your thoughts on the pump I already have. It will be connected to a verticle double mechanical releaser.
specs on pump found here:
http://www.gastmfg.com/product_detail.aspx?ProductID=137&ProductTypeID=21

[GeneralStark]

According to the performance curve for that pump is looks like it will provide about 2.5 CFM at 25". At 100 taps/CFM it looks like 250-300 would be the max if you are hoping to maintain 25" at the taphole. This would of course depend upon your mainline sizing and lengths, whether you are using dry lines and how far the pump is from the releaser and the size vacuum line you are using.

[western mainer]

I think you will find you can run 1,000-1500 taps on this pump. That's what other sugar makers are getting.
Brian

[whalems]

I think you will find you can run 1,000-1500 taps on this pump. That's what other sugar makers are getting.
Brian
I am hoping to get to 1200 this year we shall see it handled 500 taps no problem. so we will see. Thanks

[madmapler]

I posted a thread here a while back asking if I could run 2 pumps in the same system and nobody seemed to see why not so I bought 2 gast 2565s and I'm going to run them together on the same gas engine. You could do the same with electric too I suppose. A couple hundred bucks for another pump is'nt too steep an investment and 40 plus cfms should be quite effective.I'll be doing a little less than 1000 taps on this line. Should be interesting.

[GeneralStark]

I think you will find you can run 1,000-1500 taps on this pump. That's what other sugar makers are getting.
Brian

Sure, you can hook this pump up to your tubing system and get some vacuum at the taphole, but you are not going to get high vacuum at the taphole with more than 300 taps with this pump unless you have zero leaks and minimal mainline.

Are the sugarmakers that are getting 1500 taps on this pump getting high vacuum at the taphole or producing .5+gal./tap? I doubt it.

There is a big difference between playing around with vacuum and doing it effectively, and using this pump for anything more than a few hundred taps is playing around.

For those of you using this pump, how much sap and syrup are you producing?

[western mainer]

Most are getting 25 at the end of the lines, and they all love this pump. You can run numbers in till your blue in the face I know I have many times, but alot of the time it's not the same in the real world.
Brian

[GeneralStark]

Most are getting 25 at the end of the lines, and they all love this pump. You can run numbers in till your blue in the face I know I have many times, but alot of the time it's not the same in the real world.
Brian

How much syrup are they producing? I just don't see how a 2 CFM pump (@25") can effectively produce high vacuum for 1500 taps, but maybe there is something I am missing.

[madmapler]

The only real experience I have with running these pumps is my 2065 which is essentially the same pump as the 2565 but rated for 4 cfms less. I pulled 26" with 100 taps and my main line was'nt set up real well.(Lots of sags) I did get well over 2 gals. per tap on a few good days. 2.5 on one. Honestly though, I think G.Stark is mostly right as far as how well it will do at 1000 taps. These however are great little pumps and they dont use a lot of power and they dont have to be water or oil cooled. I like them because where I am there are a lot of decent little bushes around and you can have several of them set up for not much money. Granted the releaser costs some but small releasers are more affordable too. As I said before, 2 pumps at 1000 taps or so is what I'm going to try this coming season. I've got a sihi 2 stage pump sitting in my barn but no bush big enough to make it worth dealing with yet. Emphasis on the yet!:)

[BreezyHill]

In theory the pump can handle 1650 taps....1 cfm for every 100 taps. The facts are that this is only possible if the mains are set up and sized to handle high vac in order to get the vac to the tap hole. Multiply pumps on a manifold or vac tank work fine as long as they are plumped correctly and isolated by a check valve.

Ben

[GeneralStark]

In theory the pump can handle 1650 taps....1 cfm for every 100 taps. The facts are that this is only possible if the mains are set up and sized to handle high vac in order to get the vac to the tap hole. Multiply pumps on a manifold or vac tank work fine as long as they are plumped correctly and isolated by a check valve.

Ben

How do you figure that? The pump is rated at 2-3 CFM at 25".

[bowhunter]

Ben,

Hate to burst your bubble but 1650 taps divided by 100 taps per cfm equals 16.5 cfm of vacuum pump capacity required. You would need to use 5 or 6 of these little pumps to handle 1650 taps with a well designed, tight system.

[500592]

I think he is talking about using more than one pump.

[BreezyHill]

Sorry, I do not have the information for the rating of all pumps at 25" mercury as prior they were at free air. Gast has an excellent data spec book; that has a vac curve that provides cfm across the range from 0 to 30" mercury. The standard of 1cfm/ 100 taps was at free air. Please do remember that the 100 taps is a guideline, this is for a rather tight system. The factoring in of leaks will dramatically affect the 100 tap count down; as does the absence of air in a vacuum situation affects the cfm of a pump as the vacuum level increases.

One can calculate their own pump by setting up a test device like:
Stainless steel milk pail, stop watch, calculator, pen and paper .
Calculate the volume in gallons of the milk pail...many average pails are 5 gallons but there are a lot of different sizes.

There is 231 cu inches (CI) in a gallon. 1728 CI in a cu foot (CF), thus a 5 gallon pail is 1155 CI or .668 CF (5 * 231= 1155/ 1728= .668).

Connect the pail to your system by way of a valved line.

Connect the pail line to the pump after the check valve and the water separator. Close valves to all main lines and turn on the pump and start the stop watch with the valve to the pail closed. As soon as the needle starts to move you have removed all free air from the system. Stop the watch and note this time as WST. This is the time to evacuate the water separator and the tubing. Open the system to free air so as to achieve zero vacuum again. Open the valve to the milk pail...start the pump and watch. Stop the watch as soon as the needle moves again.
Subtract the WST value and this is how long it takes to evacuate the free air of your pail, note as PT(Pail Time). The PT divided into 60(seconds/Minute)= times/ minute the pails volume will be evacuated per minute. Use this value and multiply by the pails CF value and you have the CFM/ minute of the pump.

Below I have done the math for one of my pumps. I was unable to get a free air value at this time as one pail is to small of a volume to get a time. The needle moved instantly on startup on a Delaval 73. So What I did was run the pump to maximum vacuum, 29", and open the valve to the pail and start the timer. On five trials it took an average of 4.62 seconds to reach 25" and 12.6 to achieve 29".

Pail size is 5.8 gallons. 5.8 * 231 = 1339.8 for CI
1339.8 / 1728 = .775 CF
60 / 4.62 = 12.987 evacuations / minute
12.987 * .775 = 10.065 CFM at 25"

60 / 12.6 = 4.762 evacuations / minute at 29"
4.762 * .775 =3.69 CFM at 29"

This pump is being run at 1000 rpm with a 1.5 hp 115 volt Elec motor. Currently the pump is not flooded but this is planned for 2014 season. This system can be used out on your mainlines to calculate CFM there also.

It would be great to hear back from as many of you with different pumps so that producers can get an idea of the capacity of different pumps.
I have a bb1, delaval 75 and bb4 that I will be testing in the furure. Please note the rpm of the unit. This is done by motor rpm * circumference of the motor pulley / by the circumference of the pump pulley.

As you can see the higher the vacuum the less CFM the pump can produce. This can be altered slightly by rpm.
I was told by a delaval tech the 73 was at least 25 cfm and another said closer to 30. That would explain why the vac at zero jumped the needle instantly on startup. I do have a 500 gallon surge zero tank that I can setup and check the free air cfm, at a later date. I strongly urge producer to only use a zero tank and not a plastic tank; as plastic tanks are not designed to handle stress of vacuum and will result in a rupture situation.

As a side note the more precise and number of times you replicate the test the more precise the average will be.

I hope this helps to explain my statement. Please let me know if I missed anything.

If there is a study I have missed, where they are saying we need 1 cfm at set vacuum reading to achieve good production, please share it with me. A link would be awesome. Thanks

Ben

[GeneralStark]

In the following webinar hosted by Steve Childs of Cornell (click the link to go to the general listing and then click "view" for the maple vacuum systems webinar) he clearly explains why the 1 CFM/100 taps rule is not at free air and is instead to be used at the desired vacuum level.

http://maple.dnr.cornell.edu/web/schedule.htm

It seems odd to me to suggest that the 1/100 rule would be at free air as the point of a vacuum tubing system is to remove air from a sealed system is it not? The only time you may come close to running a system at free air is if you had all your taps pulled with the vacuum pump on, and this is clearly not a scenario that would be effective for removing air from a sealed system or for collecting sap.

In the webinar posted above, and in other literature like the Cornell Tubing Notebook describing Cornell's research on vacuum tubing systems, it is clearly explained that in determining the proper pump size for a system, one must consider the CFM rating of the pump at the desired vacuum level. If one wants to operate their system at 15", the cfm rating at 15" should be used for designing the system. If one wants to operate their system at 28", the cfm rating at 28" should be used in designing the system. This is based on the fact that the pump must work harder to maintain the desired level of air removal from the system at higher vacuum levels.

Consider this example: (a graph is provided in the webinar)

A vacuum pump rated at 60 CFM at 15" could likely handle about 6,000 taps at that vacuum level. However, that same pump operated at 24" could only provide 20 CFM of air removal and therefore could likely handle about 2,000 taps. Same pump, different vacuum level. Using free air ratings for anything is pointless and there is no way around that.

The 1/100 rule is a general rule and is based on a system with few leaks. Different systems will operate at different CFMs based on many factors, but 1/100 is a pretty safe rule. That said, many are now using 1/50 as a more conservative rule to base their designs upon and this seems wise for larger systems with more leak potential. 1/100 is probably safe for smaller systems that are well maintained. Whichever rule you choose to use, it should be applied at the vacuum level that you are trying to achieve at the correct pump cfm rating.

In the case of this Gast pump, which according to Gast's literature and the performance curve for the pump, we are talking about a pump rated at about 3CFM at 25". If we apply the 1/100 rule, then this pump can likely handle about 300 taps at 25". If lower vacuum levels are desired (but what is the point in that), then more taps could be handled by this pump. If we apply the 1/50 rule, then this pump can likely handle about 150 taps at 25".

The key thing to consider here is that vacuum tubing systems do not operate at free air conditions, unless you have some significant leaks, so the system should not be designed considering that scenario.