March Pump Probs

[shaunous]

Anyone have problems with their March Pumps playing up and not pumping until you turn them off and let the liquid gravity feed back into them, sometimes on and off a coupla times, or the flow just stopping mid recirc, pump motor still going but no flow.

They are clearly not positive displacement pumps as they'll run and no liquid moves (like a car water pump) unless primed, unless mines really stuffed.

I have a head pressure to the pump of about a foot.

When it is pumping its great but sometimes it's a pain to start the flow off, and sometimes it stops flowing but you think it still is cause the motors going.

I'm asking this as mine is an absolute prick to take off my brewery, let alone trying to get all the fittings back in without leaking again like older fittings like to do once touched. If it was easy I'd disassemble it

 

[barls]

They are a variable displacement vane pump so they need to be primed before they work well.

 

[shaunous]

Both my current outlets go to vessels only with no restrictions, pipes from outlet of pump open ended into vessels. Mmmmmmmmmm

 

[barls]

It helps if you set up the pump with the outlet at the top as this will help the pump to self prime and deal with the small amount of air introduced when changing configuration

 

[HBHB]

Try getting it a bit lower to allow for better priming. Had same issues with one of mine.

Martin

 

[Parks]

It helps if you set up the pump with the outlet at the top as this will help the pump to self prime and deal with the small amount of air introduced when changing configuration

Note that this actually means having the outlet sideways. If you open the head of your pump you will notice that the hole for the outlet, when at the top has the thread horizontal.

 

[spudfarmerboy]

March pumps are just a basic centrifugal pump with a magnetic drive.
As with most (all?) centrifugal pumps, they are not self priming so rely on having a flooded suction (inlet). That means the pump body needs to be liquid filled.
Any air in the impellar body will make it hard to pump, as pumps can't pump air or gases, thats what compressors are for.
The pump is best mounted with the outlet at the top and the vessel being pumped from, above that.
Also, a valve on the outlet that you can open to atmosphere, and drain from is handy as you can then be sure that you have the pump body completely full of liquid.

 

[Parks]

I find that adding any pressure to the system causes headaches. Even to the extent that if my wort return is submerged, un-submerging it will allow flow to happen.

 

[Parks]

The pump is best mounted with the outlet at the top

As above I disagree with this, at least for my model (and I would be very surprised if it's not the same across the board).

Here's an image I stole from another site explaining why:

 

[Kranky]

Any airpockets at all can cause issues. Here's a few things I do that might help:

* Keep your tubing as short as is reasonable for your setup.

* Put a valve on the exit of your pump and use that to start and stop the flow (this made a big difference for me).

- When you first prime let the liquid flow by gravity into a container on the ground for 30 seconds to a minute. Make sure you have a good flow coming out.

- Once primed close the valve on the exit of your pump.

- Connect to your receiving vessel.

- Turn your pump on.

- Open the valve on the exit of the pump.

This seems to work fairly well. Remember that when you first start using a pump on your mash to release the valve slowly to avoid it getting stuck.

If for some reason the flow rate slows or stop just repeat the procedure. If you can't get a good gravity flow rate out of your MT then that's another issue.

 

[TheWiggman]

As with most (all?) centrifugal pumps, they are not self priming so rely on having a flooded suction (inlet).

Just an FYI, but some centrifugal pumps are self-priming. They require a special expeller incorporated into the housing (the ones I've dealt with anyway) and a 'degassing' line for the air to escape. They also require a seal flushing system to prevent overheating, even on mechanical seals.

On-topic - the problem is likely air, but could it also be a 'stuck mash'? If the suction gets blocked then turning if off may allow some slight backflow and clear the mash. It depends on what you're doing with it. Being magnetic drive, it'll happily run if there's a blockage without the impeller rotating.

 

[spudfarmerboy]

As above I disagree with this, at least for my model (and I would be very surprised if it's not the same across the board).

Here's an image I stole from another site explaining why:

March pocket.jpg

You'll find that if the inlet vessel is higher than the pump, you won't get that air pocket thats shown in your diagram as it is pushed out by gravity. The same as its done in industry.
Let gravity be your friend and you'll be fine.
If you have a valve to atmosphere that you can bleed the pump from, that is, bleed out all the air and only have liquid in the pump, you can't go wrong.

 

[spudfarmerboy]

Just an FYI, but some centrifugal pumps are self-priming. They require a special expeller incorporated into the housing (the ones I've dealt with anyway) and a 'degassing' line for the air to escape. They also require a seal flushing system to prevent overheating, even on mechanical seals.
.

Thanks Wiggman, I wasn't 100% sure, hence the (?).
Cheers

 

[Parks]

You'll find that if the inlet vessel is higher than the pump, you won't get that air pocket thats shown in your diagram as it is pushed out by gravity. The same as its done in industry.
Let gravity be your friend and you'll be fine.
If you have a valve to atmosphere that you can bleed the pump from, that is, bleed out all the air and only have liquid in the pump, you can't go wrong.

That is fine, but having it pointing up cannot possibly be better. It may not be worse given that once the pump starts pumping it may quickly remove that air.

Either way, I don't think that pocket is the issue. I find having lines too long or looped to be the biggest problem. Also having a closed circuit really causes me some problems if the pump has air in it.

Note: I only use my March pump for recirculation through a plate chiller (from kettle to pump to chiller back to kettle).

EDIT: I do also agree that gravity is your friend

 

[spudfarmerboy]

That is fine, but having it pointing up cannot possibly be better. It may not be worse given that once the pump starts pumping it may quickly remove that air.

Either way, I don't think that pocket is the issue. I find having lines too long or looped to be the biggest problem. Also having a closed circuit really causes me some problems if the pump has air in it.

Note: I only use my March pump for recirculation through a plate chiller (from kettle to pump to chiller back to kettle).

EDIT: I do also agree that gravity is your friend

Parks, agree with you about a small air pocket, won't cause much of a drama if the majority of the pump body is liquid filled.
Also agree about the hoses being too long and looped. If you want to get rid of the air, a closed system is no good, you've got to have a way to vent the air. Even if its just getting the hose on the discharge of the pump and laying it down so that the outlet of the hose is below the pump. That will vent the air easily.
I use my march pump to pump from my MLT, HLT,kettle and pump through my herms and never have any problem getting a good flow.
The first time I use it on a brewday is to pump liquor from the HLT to the MLT. I open the vent valve I have on the discharge of the pump, the liquor flows out which has bled out any air in the pump body, close the valve and away it goes for the rest of the brewday without problems.

 

[squirt in the turns]

I had intermittent problems getting my March pump to prime. I put a bleed valve on the outlet but still had issues.

I ended up putting a T on the inlet, so that the pump could be primed by the feeding vessel, OR by forcibly priming it from the mains, which is hooked up to the T via a ball valve. This is a HERMS, so I fill the MT from the HLT and check that it's recirculating properly before I mash in. If I have any priming problems, a quick blast of the mains through the pump inlet fixes it every time. If there are priming problems at any point later in the brew day due to changing hoses around or whatever, I just repeat the force priming. Dilutes the wort with tiny bit of water every time but it's negligible.

Parks, I do the same as you, recirculating through a plate chiller in addition to recirculating the mash. I make sure to hook up the pump and chiller well before the end of the boil so that when I force prime, the additional water is thoroughly boiled. Of course you're probably already running the pump for at least 10 mins before the boil ends to sanitise it and the chiller anyway.

Hopefully what I've described makes sense. The rig's actually in pieces right now but I can post a photo once I've put it back together if need be.

 

[shaunous]

No closed system, all open.

I see what your talking about with the pocket of air, same theory as my comparison to a non positive displacement pump (car water pump), so the ones saying there is a pocket of air if the outlet hole isn't at the top would be correct. Although once the pump primes and pumps this will go away, but for some time once starting it will make priming and pumping harder.

Mine seems to be set up 'incorrect', also as it had some use and about year off I'll disassemble and clean. But I'm not changing it's set-up unless really needed.

 

[shaunous]

I get what u mean Squirt.

 

[TidalPete]

Nobody has yet mentioned that the impellor might be gumming up on the shaft & stopping/starting due to an inadequate cleaning regime?
I sympathise with you shaunous in regards to your inability to strip the head of your March when you need to do so. Perhaps you need to reposition the pump to benefit your brewery in the long run?

When I ran a March 809 & did not have a proper cleaning regime I found that I had to occasionally strip off the head off the March & get rid of any gummy stuff between the shaft & the impeller by scrubbing in hot water before re-assembling.

Since moving on to a March 815-PL-C I've had no hassles at all but probably due to a more vigorous cleaning regime combined with the faster recirculation & my normal priming method as posted below.

Absolutely agree with those who advocate a bleed valve at the lowest point of the brewery. This is elementary.

When starting up on brewday at the correct temp I open everything, close that red-handled tap on the RHS & disconnect the hose to prime.
I close the lowest valve in the centre of the pic then close various other valves to direct my HLT to underlet & away I go.
Hope this helps?

Edit ---- Please not that both My March 809 & 815 have both run in the same horizontal position & NOT the vertical.

 

[shaunous]

Yeh had a tipoff about the gummy shaft thing, I'm used to fancy pumps where that would have never been a prob. I will disassemble and wash, as it's real real annoying.