Vacuum relief valve

[jasonl6]

I am working on a new vac system and need a large relief valve for 1 1/2" or 2" pipe. Needs to be able to hold 25" of vac. I used the system last year without one and had an issue where my electric releaser would not dump fast enough and the moister trap worked thus not letting any air get past the pump. After that i installed a ball valve and cracked it open but i would like an actual mechanical valve. Anyone have an leads on where to get one?

Jason

[mapleack]

Jason, I use a brass 3/4 adjustable relief valve from mcmaster carr to regulate my system, http://www.mcmaster.com/#vacuum-relief-valves/=ldi7hk . Im assuming your electric releaser pumps out the sap? Perhaps you need a bigger pump on it, allowing you to leave the vacuum level set higher? Also, if it is a pumped electric releaser, do you have an equalizing line from the discharge side of the pump back to the releaser so the pump isnt fighting vacuum to start pumping?

[unc23win]

Another place to get some vacuum supplies http://www.partsdeptonline.com/Gauges-Regulators/products/142/ it is a similar regulator. You tighten it to the desired vacuum level.

[DrTimPerkins]

Jason, I use a brass 3/4 adjustable relief valve from mcmaster carr to regulate my system...

Just realize that a vacuum regulator typically keeps the vacuum at a constant level by bleeding air into the system.

[jasonl6]

Thanks for the info guys, Actually the pump had a glitch last year, I'm helping a farm that has had very little work on they sap system for 8+ years. The pump needed rebuilt but was plenty big, On huge runs it just couldn't keep up. The pump will be replaced for this year but want the system to breath if i have an issue. I read were the 3/4" is only good to a 1.5 hp system, The pump is a 5hp SIHI pump so i'm afriad these won't be big enough. The system had a large 2" vacuum regulator on it when it was install new 12 years ago but the spring is so week it opens at 10-12" now, It's not a serviceable part either so it needs replaced.

Jason

[mapleack]

Looking around online I can't find large regulators that go higher than 15", and they are expensive. Is the vacuum pump a liquid ring? If so why not let it run as high as it will run and not worry about it?

[unc23win]

https://www.bascommaple.com/item/vpreglap20/vacuum_regulators/ $72 ouch

[Mark-NH]

I am wondering why we need a relief valve on our vacuum systems? We know the max is 28" and we know the system is set up to handle maximum vacuum. What am I missing? Do i need a relief valve or is it more for piece of mind. If not needed, it is one less thing to worry about and one less thing to go wrong.

[Sunny Hill Farm]

Here is a link to what we have used:

http://www.morousa.com/Valves/Vacuum-Relief-Valves/1-1-2-Inch-Vacuum-Relief-Valve.html

They are used on Vacuum Tank truck as a relief and can be set for any level.

[BreezyHill]

For livesock and for tanks that are not rated to high vacuum. This is the only reason to run a relief valve.

Cooling a pump should be accomplished externally or by reducing the friction with oil introduced to the pump thru the vacuum line.

Zero Company made tanks that were designed for milking and the older and newer tanks are made of a heavy stainless. There were some tanks that failed as they were made of a light gauge SS.

The introduction of air into the pump will cool the pump but it is costing you production according to Dr Tim's and Steve Childs reports.

Yes cooling a pump is important but it is best to do this with a fan externally or with cooled oil from a reclaimer.

I reman dairy pumps to operate efficiently at high vac. Oil, and the right oil is very important to a cool pump. Air will have a percentage of water in it even thru a cooled moisture trap. This water can and will cause damage to the pump over time.

I have seen pumps that were destroyed by water in the oil. Bearings rusted tight to pitted bearings.

I run a glass releaser and tubing system this season and have learned a lot of how air leaks splash the sap around. I have a 5 gallon SS water trap and get sap in it every day from condensation and the pumps still are getting a little moisture in the reclaimer water drain.

Hope this helps answer your questions.

[ToadHill]

Not all electric releasers can handle high vacuum. The releaser pumps have limits as to how much vacuum they can overcome to dump the releaser. I have a belly releaser with a 1.5 hp thermoplastic pump. It worked fine with my single stage 3 hp Sihi vacuum pump that would pull 25-26", but my new 7.5 hp double stage Sihi will pull 28" and I doubt my releaser pump can handle it, i.e. I have a vacuum relief valve that I adjust to 26". Eventually I plan to try one of the new electric releasers with the submersible pump located inside the releaser so it doesn't have to overcome the vacuuum. Then maybe I can crank it up to 28" and do away with the relief valve.

[BreezyHill]

Not all would be a safe statement. The 12volt pumps that are low flow will be one.

I run 28" plus on a remanufactured Delaval and my Doerr electric pump handles it with no hesitation, evacuating over 1/2 gallon per second out a 1.5" line.
This is a centrifugal pump so it handles any slush without issue.

Diaphragm pumps will be another story.

The pumps should not "fight to start pumping" if they are contained in the system loop and have the check valve located after the pump discharge. If located after the check valve then it will fight to prime and have to over come a check valve and will have drastically reduced flow.

It is all in the design of the system... horse then cart works best. Spend a few extra dollars on a pump and a few minutes designing the system to achieve the best possible results and the headaches and hassles will be fewer.

The added production from two more inches on a system will often more than pay for a higher quality releaser pump.

Best Wishes!

Ben

[ToadHill]

Ben, I think I understand what you are saying, but can you explain what you mean by "contained in the system loop." Also, my check valve is on the discharge side of the pump and there is an equalizer line between the pump discharge line and the releaser. It is connected between the pump and the check valve and runs back to the releaser. My understanding is that this line puts vacuum on both sides of the releaser pump so it doesn't have to overcome the vacuum to empty the releaser. Also, there is a check valve in the equalizer line that allows liquid to flow from the pump discharge line back into the releaser. I have had discussions with others regarding the equalizer line check valve and I have gotten conflicting directions on how it should be installed. According to the directions I received from the manufacturer the flow through the equalizer line should be from the pump discharge into the releaser, but some contend that the check valve should be installed in the other direction. I'm not saying that is wrong, but I don't understand the logic and it is counter to what was in the instructions that came with the releaser. Randy

[BreezyHill]

Randy, I do not use a equalizer line or a balance line. To me this is oxy moron.

In the loop is: all things in order. Tree, tap, lateral line, mainline, manifold, releaser, releaser pump( if used), tank.

The discharge line from the pump is for flow away from the releaser...too pump product back to the releaser is counter productive.9308

This is a pic of when I was remodeling our system. The pump is after the releaser without any balance line. Works great.

If the pump is to small and you need to have a vacuum line on the discharge of the pump...get a better pump.

My system works at 28" all day long, with no issues. Weather the releaser is part full or to the top, or draining when it is going to freeze the pump sends it out in a blink of an eye.

[ToadHill]

Ben, When you place a vacuum on the suction side of a releaser pump you are adding to the head the pump has to overcome to pump the sap out of the releaser. Not all pumps can overcome the high vacuum. It is particularly hard on a pump at startup. It has also been know to damage the seals in the pumps. By installing an equalizer line there is vacuum on both the suction and discharge side of the pump and the pump doesn't have to overcome the vacuum on the suction side. The equalizer lines are usually a very small tube or a larger pipe with a valve in it. Either way only a very small insignificant percentage of the flow goes back to the releaser. This is the way that manufacturers set up electric releasers made for the maple industry. Dairy ones probably don't have this feature because they are not intended for high vacuum applications.