Feed Pump Pressure Drop

[Amber Gold]

Typically when I start the RO, I have to watch the feed pump pressure to make sure it doesn't drop too much while increasing the HP pump. I think this is because it's still taking air out of the system. Usually, once all the air is out life is good and I don't have to worry about the feed pump pressure. Lately though, it seems like it's been more finicky, particularly the last time I ran it. It took me about 15 min. to get the HP pump to 250psi becuase I would raise the pressure 20psi, wait a few minutes for the feed pump pressure stabilize, raise it another bit, and repeat the process. This even occured once it shut off because it ran out of sap and needed to be restarted to rinse with permeate.

Does anyone know why this is and how to fix it?

Thanks

[sfsshadow]

must be sucking air from some fitting

[Brent]

Sounds like it's starving of feed sap somewhere and sucking. Have you checked the strainer and 5 micron filter?

Maybe the O rings on one of these is damaged. There might be some debris in the feed line before you get to the
coarse strainer.

[maplecrest]

when feed pump pressuredrops means dirty or clogged filter

[Amber Gold]

How often should the filter be changed? I've put 2500-3000 gal through it since the start of the season. I do use the cloth filter wraps which get washed every time.

I don't believe there are air leaks because the flow meters are running clear. When I first start up, the concentrate meter is sucking in a bunch of air and is cloudy.

[Brent]

I would think it should be changed at the start of every day.

Someone post here a few days ago to keep one filter for washing. Do the wash and the flush with it. When everything is clean, put in new one to start the concentrating.

Just think about all those microbes sitting in a heated RO room all night in a high sugar environment, doubling the population every 20 minutes. UUUGGGGHHHH.

I learned this lesson the hard way when I first started playing with the little GE Merlin RO

[Maplewalnut]

Josh-

I change my prefilter when pressure drops to 25-30 psi. By then it is visibly dirty all the way to the core. Otherwise I reuse everyday and switch out to a second filter for cleaning and rinsing only.

Mike

[Amber Gold]

I put a new filter in yesterday and it worked fine. Problem solved. Thanks

My feed pump pressure is typically about 35psi. Is this normal?

[maplwrks]

35 psi will work just fine

[Russell Lampron]

My feed pump pressure is 65psi. Maybe the impeller in the pump is full of debris. I think it should be higher than 35psi.

[802maple]

I would check the impeller, they will often get clogged, especially if any bucket sap is going thru it. That 250 machine should have more than 35 psi like Russ said. I highly recommend a inline strainer to my customers just before the RO to catch critters and any thing else that might get to the feed pump.

[sapman]

My feed is typically 40-50psi.

[Amber Gold]

Is there any special gasket or anything where the pump head cover bolts on? I just want to make sure if I pull it off that I can put it back together w/ out anything special.

Anything in particular I'm looking for on the fins? I don't know when I can take it apart, because I work all day and when I get home it's already running. It also spent most of it's weekend running.

I don't know why, but lately I'm having a hard time getting feed pump pressures greater than 25psi when I feed from the permeate tank. Coming from my sap tank is fine, but if I switch to the permeate tank to do a rinse and when I kick the HP pump on, the feed pump pressure drops, then I fight trying to get it back. It seems to run fine though when doing a rinse cycle after a wash cycle (no HP pump). Any ideas what's going on?

Thanks

[danno]

Josh -

Does your permeate tank run into your RO the same as your sap tank? Same head pressure, same pipe size?

yours runs the same as mine. I change filters often, but my feed pump pressure always maxs out at 20. Getting the HP pump to stay on when I begin concentrating/washing/rinsing can be a bit of a pain. Sometimes takes two or three trys. Works best when I purge the line of air (open the valve in my washtank for a couple of seconds). Once all the pumps stay on, I'm fine and they stay on until I run out of sap (or permeate if I'm rinsing).

I was talking to the guy I bought it from yesterday and he asked, other than the low pressure, is everything else working? Are you making concentrate? He suggested if so, leave it alone until after the season. This makes sense to me unless you get to the point where pump won't stay on.

[Brent]

our Airablo also drop feed pressure when the high pressure pump runs. It only makes sense that if you are sucking sap out of the feed channel that the pressure there will drop.

As Danno noted, air in the system will cause the drop to trip the low pressure limit and shut the whole thing down.

[maplecrest]

josh when and after you get your r/o straighted out. orlon sap filter bags are cheep easy way to prefilter sap. and save alot of head aches . and they wash out with a garden hose.get them at any maple supply place or bascoms. i just tie them on the end of the pipe going into feed tank of r/o

[Russell Lampron]

Josh I'm not sure if your pump has a reusable gasket or not. Check to see if it rubber before you take it apart. If it is rubber it should be reusable. The last owner could have sucked some leaves and stuff into it. That will clog up the impeller and cause the pump not to build pressure. I think maplewrks had that problem a couple of years ago.

[Amber Gold]

My bulk and permeate tanks are all enclosed so they are clean. Sap dumping into the bulk tank runs through a bag filter. Russ was there when I started the RO this season and he commented on the low feed pump pressure. I know the RO is about 7yrs old with the feed pump replaced 3 or 4 yrs ago.

If there isn't a rubber gasket, is RTV sealant suitable? I'm holding over the 450 gallons of sap I have to process tomorrow...try and get caught up on stuff...sleep being one of them.

All lines feeding the RO are 1". The bulk tank is outlet is higher than the feed pump, the permeate tank's is lower, but there's plenty of water head (3') to get sap to the RO.

I'm debating between leaving it alone until after the season...it at least works, or taking it apart tonight.

[Maplewalnut]

Josh- I would try and limp through the season as is. Optimize and troubleshoot after the season.

[mapleack]

All lines feeding the RO are 1". .

The manual for my new 250 says that 1.25" should be the minimum line size I believe. Might be part of the problem.

[802maple]

What brand feed pump do you have on the machine? A grundfos can be a pain to get back together at times. Others are quite easy with just a large O-ring.

Certainly the 1 inch line can play into the low feed pressures. Our first unit had a feed tank that the bottom was lower than the RO and it was a pain in the a#$%. Is the permeate feed tank further away then the sap tank?

[Amber Gold]

I think it's the standard lapierre feed pump, but I'll confirm when I get home. It's blue.

The storage tank is an 8' straight shot to the feed pump. The permeate tank has about 10' of pipe, but it has 3 elbows to get to the feed pump. The previous owner fed it with a 1" line, so I assumed it'd be adequate...maybe not??

The other issue I'm having is when the pump shuts off, the water/sap drains back into the tank and freezes at night. I've watched it and the pump will suck the tank drain, but then it just drains back...not sure if this is indicative of something or not, but next year I'll be installing check valves before it exits the RO room to keep this from happening.

[Gary in NH]

I'm wondering if the air you saw was the result of cavitation on the suction side of the pump. If the sap can't be drawn into the pump fast enough the vacuum can cause a portion of the liquid to turn to vapor resulting in air in the pump which is damaging to the pump. An under sized feed line would cause pump cavitatation assuming nothing is internally restricting the line, like ice. If it's not any of the above a real long shot is the pump motor maybe running backwards. I don't know the details of your pump or motor but I have seen this happen. If you can see the motor shaft look at the rotation as it shuts down to see if it's going the right way. An alternative to the check valve if it's PVC would be to put in a true-union ball valve and just close it as you shut off the feed pump. It will stop the back flow and you can loosen the union and drain any remaining sap out of the feed line to prevent freezing. A swing check or spring check will add a little more restriction on the suction side of the pump and any debris in the sap could cause them to not seat properly.

[802maple]

From my experience I would say it is a combination of a lower tank, with elbows that restrict flow and a longer pipe, plus to small for both sap and permeate.

[Brent]

Josh
Tonight I fired up our RO to clean the new membranes and was reminded of what I did last year and what was referred to above. Feed tank height. The feed pump wont suck worth a darn. I started off ok tonight when the tank outside was full, but when I tried to restart with the tank low ... lower than the pump by now ... I could not get it back up to the 50 + lbs that it did when I started. Then I remembered, last year I had the tank up on about 6 skids to keep it high enough, even when empty.

Tomorrow the skid brigade kicks in ... for the feed tank and the permeate tank.

[Amber Gold]

Feed pump pressure update.

It's gotten harder now to draw from the perm tank and when I do, the flow rates when doing the final rinse after a wash have dropped from 2.1gpm to ~1.75gpm. Also, I'll have to double check tonight, but the pressure pulling from the wash tank has also dropped a bit and I want to say it's gotten harder to pull from the bulk tank...will need to double check that as well. I'm starting to lean towards a problem with the pump itself whether it's something which can be repaired or a new pump is needed, I don't know.

Keep in mind I started the season w/out having any issues maintaining 36psi regardless from what tank I was pulling from and not having to deal with pressure drops when starting the HP pumps when doing a perm. water rinse.

[Brent]

If I was hitting your frustration level I'd be pulling the pump apart to look for debris in the impeller. Then try pushing a wire or something like that to try to find some debris in the plumping ... and confirm that the valves are really open ... if you're using plastic ball valves I have seen some of mine shear the coupling of the handle to the actual rotating ball, leaving the port obstructed even though the handle was in the open position.

[Brent]

The other issue I'm having is when the pump shuts off, the water/sap drains back into the tank and freezes at night. I've watched it and the pump will suck the tank drain, but then it just drains back...not sure if this is indicative of something or not, but next year I'll be installing check valves before it exits the RO room to keep this from happening.

Get the tank up higher so the bottom is above the pump.
It is a royal pain trying to work with a lower tank. You will get this drainback issue every startup unless you put a valve in the line.

Not only does it get air into the pumps but it can suck air right into the membranes and you should not be increasing the pressure on the membranes until this air is out. On my system that can take 10 - 15 minutes. I'm putting a vavle in the line between the pump and the stainless steel strainer so I can clean the strainer without intrducing much air.

You should have a bleed push button on the top of the filter. I have to push that button several times to get the air out of the system when I start mine.

[Amber Gold]

When the tank is more than half full, the water elevation is higher than the RO intake, so I don't think it would matter at that point where the tank outlet is in relation to the RO...I could be wrong though.

My sap storage tank is higher than the RO and it still gets sap draining back into it.

When I first start it for the day, there is a lot of air in the system, even if I bleed the air out at the prefilter. It typically takes ~10 min to run clean before I can start cranking the pressures up.

I spoke to Lapierre and they said a 1" feed line should be OK, but a 1.25" would be better. He said a 36 psi feed pump pressure is OK, but typically it should be 40-50 psi. He thinks there's something inside the pump head and to take the cover off and inspect. I have a public hearing tonight and will be doing this when I get home. Hopefully everything comes apart and goes back together fine w/ no leaks...and out if anything's wrong with the pump...hopefully something simple.

The main reasons why I haven't done taken it apart yet is the RO is almost always running when I'm home and I was hoping to limp through the season as is then deal with it afterwards.

[Gary in NH]

In regards to tank height it is always better to start up a pump with flooded suction. Some pumps will still need to have air bled out of them if an air pocket is preventing the pump from building pressure. Tank height doesn't change overall pressure very much. For every 2.3 feet of liquid (water) in a column there is 1 psi of positive pressure and sap is pretty close to water. So if you have a tank that is 7 feet tall and full the pressure at the bottom tank outlet would be approximately 3 psi.

[danno]

Josh - let us know what you find out regarding the pump. I've got the same problem. Max psi is 20 on my low pressure pump. I've never had mine apart (gonna try to limp through the next week or two), but I believe my pump is magnet driven. If it's not foulded, I don't know if there is an internal adjustment. I can't find the skematics on line and the manu. is no help.

Anybody know anything about magnetic driven pumps?

[markcasper]

You had best check for rodent debris.......when I started mine 10 days ago, I lost pressure within 1/2 hour. Came to find out that a mouse or something was at one time in the plumbing and made a seed vault inside. Tore the pump apart, took every seed out of the jets with a needle and 4 hours later it was operational. Sometimes I have to learn the hard way....after season the plumbing will be sealed.

[802maple]

Mark, that is why I put a inline strainer just before the feed pump on all of my installations, they can also get in there in the season, along with other things I have seen are stones, nails, a penny, tree bark and the list goes on.

[driske]

Add hose clamps, o-rings, twine, and electrical wire trimings to that list.
Well today it's supposed to hit 38F. The rubber will have to hit the road so to speak.Plenty of challenges involving pushed out taps. Mainline freeze ups and downlimbs yet to be dealt with.
I feel like we are in some kind of wintry purgatory, with summer and things green only a distant memory and vague promise.
What do they say in VT. 802? "Nine months of winter and 3 months of tough sledding".:-|

[Amber Gold]

I pulled the cover off last night and didn't find much of anything. There were some fibers from something on the fins on the motor side, but other than that it looked spotless. Put the cover back on and ran some water through it...no leaks which is good, and still the same pump pressure. I didn't process any sap, so I don't know if I'll have the same problem pulling from the perm. tank. We have 1000 gal to process, so I'll know today if things are any different and will update the thread.

[802maple]

Driske, we say that it looks like the sugaring of the old days prior to global warming.LOL

Josh, when you were in the pump did you also look down inside the impeller by pushing a wire through. just asking.

[Amber Gold]

No...didn't know I should. I pulled the cover off and on the motor side there was a plate w/ fins and I looked behind that the best I could...pulled off the plugs and such and couldn't see anything. I'm trying to remember what's on the cover side, but I could see anything in the cover either, but then there isn't much of a space to look in...maybe I missed something??

[Amber Gold]

I've been talking to Lapierre about my pressure problem and they basically have no idea what's wrong. They are helpful, but don't know. They get 2-3 calls like this a year and I guess I'm one of them. It's working well enough that I can get through the season, but will be saving lots of permeate so I can tinker with it after the season's over. I'm going to re-build my intake manifold and run larger feed lines. If that doesn't work, I may replace the feed pump and see if it solves the problem.

He did say the Gould pump I have is typically in the 40 psi range, so the 36psi I get is OK. He did say the Grundfos pumps run at higher pressure...50+ psi

What size feed line is needed for a 600 gph RO? I want to size it appropriately so I'm not building it again if I rebuild.

[mapleack]

The lapierre manual says 1.25" feed lines. When I put in my 250 this year I did everything with a 600 in a few years in mind. The only thing I should have to do for a 600 is replace two half inch fittings on the 3 way panel with 3/4" ones and I'll be good to go.

[802maple]

That is a good idea Mapleack, when I set up a new setup, I, ask the customer what his dreams are and then plumb for that. For instance I just installed a 600 with 2' lines because they believe they will be having a 1200 within a few years. It doesn't cost that much more to oversize and not have feed problems. besides you won't go thru as many filters either.

[Amber Gold]

Jerry, why will you not go through as many filters w/ the larger lines? Is it becuase you're just flowing more liquid?

I increased the pipe size to 1.25" and everything works fine. Flow rates during a wash cycle increased from 2.1gpm to 2.6gpm and I have no problem now getting the HP pump going and up to pressure. I'm surprised the little bit larger dia. helped that much. Thanks for all the help with this issue.

[danno]

If my intake on my feed pump is only 1", will it help if I increase my feed line? Right now my feed line is 1" black poly pipe, but I can certainly change that out to 1 1/2" or 2" pvc if it will help. I was also having problems getting my feed pressure over 20 psi and did not know if it was the pump or the intake line. Just don't know if it would help if flow's going to get bottlenecked down to an 1" when it hits the first pump.

[vtmapleman]

I have never given any thought of using one specific filter to do the washing/rinsing - thanks for the heads up - will do next year. Yes, sound like your RO is air bound, most likely needs a new filter. My RO has a air bleed button on top of the 5 micron filter housing which helps to release the air and speeds up the liquid getting to the pressure pump.

[802maple]

Josh, you won't go thru as many filters because you start at a higher pressure so it takes longer for it to get to 20 psi before the machine shuts off.

Danno, you are working under pressure on the exit of the pump, so you aren't able to get as much sap to the pump with a small 1" line.

Never use the same filter for washing as you use for concentrating and rinsing, as you still have soap residue in it.

[Brent]

Danno
your feed pump may be starving a bit. What Hp is it ?
You also need to consider how long the feed is from the tank, how many elbows, valves etc are in the line, if the strainer is sized right ( I would assume the strainer was put on by the manufacturer so it should be Ok) and very important, what is the relative elevation. I have about 20 ft of hose and put my tote up on a stack of skids so the bottom of the tote is about 18" above the pump. This bleeds out all the air pretty easy ... a real gusher if the tote is full because by then its up about 6' above the pump.

[danno]

Sorry for the stupid question - I've heard this mentioned before. What's a strainer? Is this the 5 micron filter you're talking about.

I will try the larger pipe/tank valves next year, it can't hurt.

[Brent]

I think most rigs have a stainless mesh in a cartridge holder for coarse stuff, about 100 micron. The stainless mess is about 1 or 1-1/4" long x about 4" on mine and has a container that thread off just like the 5 micron fine filter. Mine mostly seems to catch flies and moths.

[802maple]

Danno, this is what I put in every installation, as Brent says it most likely will only catch moths and flies, but the first time it catches a nut or penny or mouse it is worth its weight in gold.

From Granger
Y Strainer,2 In,30 Mesh,FNPT Poly
$49.65
Item #: 3DUC5

[Amber Gold]

So, I upgraded all the plumbing to 2" PVC right to the pump, where it reduces to 1.25" for the pump inlet. No issues getting the feed pump to operate, but it only runs at 32-34 psi. Flow rates during a wash/rinse are 2.1-2.5 gpm. Are these normal ranges? I thought I recall some w/ Lapierre's getting 50-60 psi on their feed pump.

[Maplewalnut]

Josh- I have 50-60 psi with new pre filter but it drops off slowly after that. Did you bleed all the air out of the system?

[Amber Gold]

Yes. No air in the system, and I get 32-34 with a new filter and whether I have the wrap on it or not. Also, only get 32-34 during a wash/rinse cycle. I've never seen the pump get higher than this, even last season when I had smaller dia. piping...thought the bigger piping would fix this problem. Last season, I took the pump cover off and inspected it and it looked fine...couldnt' see anything obviously wrong with it. Everything runs fine, just the pressure's lower than I thought it should be.

[maplwrks]

Josh---you need to bleed all of the air out. Use the red button on top of the prefilter canister. Don't start the high pressure pump until you get it a little higher, should be like 45 psi.

[Russell Lampron]

Mike what brand of feed pump do you have on your RO? I have a Grundfos on mine and have no problem getting 65psi when I first start it with new filter etc. It doesn't drop off very much after it has been running a while unless the sap is real snotty. Josh has a Goulds pump on his if I remember right. I haven't read all of the post in this tread over again but if I remember right Lapierre told Josh that the pressure was right for the pump that he has. I think they were just blowing smoke up his butt and would be interested to know if others have the Goulds pump and have the same problem.

[danno]

I had low pressure issues last year. After much investigation I found that my low pressure pump, though a beautiful pump, was rated to only do about 20 psi. I could have moved up to a bigger impeller, but that would have only gotten me to 30 PSI. Put a new low pressure pump in this year - runs as high as 65 and drops down to 45 when high pressure pump is on. I do have to make sure to bleed the air out of the pump if it's not filled with sap or permeate. When I hit the start button, she takes off immediatly. No longer holding that switch waiting for pressure to build.

[Amber Gold]

I will verify tonight the air is bled out. When I spoke to Lapierre about it last year, they weren't too concerned about the lower pressure. I started putting on the pre-filter wraps the other day and noticed it takes a bit longer to build up pressure during feed pump startup.

My flow rate during a wash/rinse cycle is ~2.2gpm. Russ says he's getting 4gpm.

Between these two things, does my feed pump need to be rebuilt? I took the cover off last season, and the impeller looked fine...nothing noticeable anyways.

Don't know if this is related or not, but for some reason, it started tripping the 30 amp breaker over the weekend.

[Maplewalnut]

I also get between 3.5 and 4 gpm on wash cycle. What pore size is your pre-filter? Could it have too much resistence there? I know of one guy who was running a 1 micron pore size pre-filter and it was shutting down on him regularly til he chnaged to 5 micron. Not sure what kind of pump I have, I'll look this afternoon.

[Brent]

After everything you've tried, I can't help but get suspicious of the pressure guage.
I know on my swimming pool system, I need a new one every year.
On our vacuum system about a quarter of them go out of wack every season. Some show 10"
when the system is shut down and everything is open.

[Amber Gold]

Lapierre 5 micron...PX-5 or something.

The pump shuts off when it drops to 20psi like it's supposed to...this is controlled by a sensor, not the gauge, correct? If the sensor shutting off the RO is correlating w/ the pressure gauge reading, wouldn't it mean the gauge is accurate?

[Brent]

The pump shuts off when it drops to 20psi like it's supposed to...this is controlled by a sensor, not the gauge, correct? If the sensor shutting off the RO is correlating w/ the pressure gauge reading, wouldn't it mean the gauge is accurate?

Yeh I think so. Where are they plumbed in. Both after the filter or one each side of it. Theoretically after the filter is better so it show/sense a drop if the filter gets badly plugged.

You got a buddy that you could borrow a similar pump from and try a test on your rig with his pump. If you get full pressure 50lb'ish
then I suspect it's time for a new pump. If you get the same result you've got a guage or feed line problem.

Remember the pressure sensors are generally adjustable, I mean the one feeding the shut off switch I recall you did not buy that rig new.
This one is a head scratcher.

[Russell Lampron]

I was at Joshes last year when he first started his RO and I noticed that it wasn't building pressure as fast or as high as mine. We have similar Lapierre RO's, his having 2 4" membranes and mine having only 1. Not seeing anything wrong with the way that his feed line was plumbed I felt that there was something wrong with the pump. We really had to wait a long time before we could turn on the high pressure pump and then carefully adjust the concentrate flow to keep the pumps from shutting down.

[maplwrks]

I have one question--Josh, have you expanded the 250 Lapierre? The reason is this--I expanded mine the second year I owned it. There now is not any back pressure on either pump. Suddenly I could not build a lot of feed pump pressure, about 40 psi. When I kick on the high pressure pump, it drops significantly, roughly 25 psi. I think the pressure pump robs sap from the feed pump. It stays right there until I am done for the day. It has done this for the past 8 years, and every year, I say that I am going to buy a bigger pump, but never do! It is a Goulds pump, I think that this all they put on the 600s now. When I do my washes or rinses, the pressure is always right up around 40 psi. I do know that initial start up for the day can be a little aggravating, trying to get the high pressure pump to stay on.

[Amber Gold]

Russ, I thnk my issue last year w/ it not being able to build pressure was due to the piping being undersized. This year it's all 2" PVC. Now I open the intake valves and start the feed pump and no issue getting to 32-34 psi. During a rinse to drain cycle, I can fill my wash tank directly from the intake line and the RO doesn't miss a beat. I have noticed if I wrap the pre-filter, it seems to take a bit longer to build to operating pressure and it seems to take longer to clear the air out of the system.

Mike, I haven't upgraded the RO in any way other than the new XLE's. If it matters, the pipes leaving my valve panel are 1"...only because I had extra blue 1" mainline I wanted to use up. I don't think the HP pump is robbing the feed pump. It runs at 32-34psi whether I'm concentrating, washing, or rinsing. If your RO's expandable, why didn't it come w/ a large enough feed pump?

[mapleack]

My feed pump runs about 50psi all the time. I've got 1.25" feed lines to it. I do however have about 8 feet of head pressure.

[Maplewalnut]

My feed pump runs about 50psi all the time. I've got 1.25" feed lines to it. I do however have about 8 feet of head pressure.

In comparison I have 1.5" lines feeding the pump with about 8 inches head pressure. I'm leaning towards the pump as the issue.

[Amber Gold]

Head pressure also includes the sap elevation in the tank. The tank's drain elevation is approximately 12" higher than the feed pump...storage tank is 30" tall. Also, the 550 gal vert. poly perm. tank is above the sap tank and the drain is say 3.5' higher than the drain on the sap tank..figure in a full tank and there's much more head pressure on the perm. tank and I get the same flow rates and pressures. I don't think head pressure, or lack thereof, is an issue.

It's working now, so that's not an issue, but looking to see if their could be an issue and what I could do to prevent it. Anyone who has a pump I could borrow, is currently using there's. This would be something to try post-season. Anyone local w/ a Goulds pump? Grainger carries them, but I think they're ~$750.

[Brian Ryther]

Josh, I would change the gauge before changing the pump. But first take the front of the pump off and see if there is anything cought in the impeller.

[Amber Gold]

Do you have a spec. on the gauge? Guessing these can be found at another supplier than Lapierre for a better price??

I confirmed last night the pump has a harder time building pressure w/ the pre-filter wrapped in one of those Lapierre filter wraps. Got it done, just took longer. It also seemed to take longer to bleed off the air. I let the feed pump run for a few minutes before starting the HP pump and no difference.

Brian, took the cover off last season and all's sparkly clean inside.

Do pumps just wear out? Would it be the pump head or the motor that's worn out?

[Brent]

There's no special spec on the pressure gauge. BII seems to be the trademark that dominates the market. Virtually all have the same thread, 3/8 NPT I think just be sure to get the same mount ... bottom or back mount. And be sure to get glycerin filled. They last much longer. You should be able to get one from a hardware store, TSC, Home Depot etc.

Pumps can wear out but it would be unlikely in a maple sap environment. The clearance between the impeller and housing is pretty important. Look at the impellers for wear.

[maplwrks]

Like I have said in previous posts, me feed pump will only put out 40 - 45 psi. I was firing up my Ro for the first time this year and I had sap running out of the feed pump, all over the floor.After using some of my favorite expletives, I got on the phone looking for another pump. After a couple of calls and $869.00 I had a new, bigger feed pump ready to go. I had a 1 hp on my unit and upgraded to a 11/2 hp. This pump pushes the pressure up to...40 - 45 psi???? go figure. I guess what I have learned here is this ,
going to larger pump may not help you either!!

[danno]

Josh -what model Goulds are you running? We can do a quick check online to see how much head/psi the pump is designed to deliver. I'm guessing it's designed to provide low pressure, maybe I'm wrong, but it's easy to check.

I only have 1" line entering my pump and my sap tank is about even with the pump. Bought a $275 pump this year and have 50-70 psi all the time.

Regarding the pressure shut off switch, check the 1/4" hose to make sure there is no blockage. Also check the back of the switch where tho hose enters for blockage. I've seen those gunk up.

[Amber Gold]

Danno. This is the pump I'm running.

http://www.grainger.com/Grainger/GOULDS-Centrifugal-Pump-4UB56?Pid=search

Where's the shutoff sensor?

[Brent]

Our RO is only rated 150 GPH by Airablo with the original PVD-1 membranes and it has the same series Gould pump

BUT it is 1 Hp. -- on a smaller system than yours. I think the pump simply undersized.

By the way I change the plumbing on ours and even though the pump intake is 1-1/4", the first fitting I put on the pump is a reducer to 1" and it still puts out almost exactly 50 PSI, so I don't think you have a problem on the intake side, unless you have a huge amount of
elbows etc.

Going back to my earlier idea, see if a nearby guy will loan you a 1 Hp pump to test. You only need to turn it on for 30 seconds and you
may have the solution to this issue.

[danno]

Josh -

The max head for that pump is 62 feet. 62 feet of head converts to 26.87 PSI. If you want more PSI, I think you need to change pumps. They do sell larger impellers for some of these pumps, you can also take a look at that option. SS impeller is probably gonna run you $150ish. If you go the larger impeller route, check the head rating on it first, it may not get you much more PSI.

For the shut off switch, just follow the 1/4" or maybe it's 5/16" (anyway, the smallest hose on the RO). It probably comes off the hose that runs between your prefilter and high pressure pump or it may come right out of the top of your prefilter housing. That small hose runs into a reverse pressure switch which is what automaticvally stops your pumps when the pressure drops.

I've seen it clog, but I think your problem is an under headed pump.

think that's your problem

[Amber Gold]

Danno...hadn't thought of calc'ing what it should be. I got the same result. If that's what the pump's rated for, then it's working fine and I'm happy. I was just thinking if mine's running @ 32psi, yet everyone else's is running 50-60 psi, then there's something wrong w/ it...guess not. I'll check the pressure line to confirm.

Brent, swapping feed pumps w/ a friend's would need to be a post-season check, but something I'm intersted in doing.

[Amber Gold]

Spoke to Lapierre and he said if the pre-filters are clean and the impellers are clean, then everything's fine. He said generally, those are the only things which reduce the pressure. He also said my 2.25-2.5gpm flow rate during a wash/rinse cycle is fine as well.