Priming A March Pump

[zephon]

Hi All,

I have plumbed my March pump using the instructions from this blog.

The main problem I have is getting rid of the air trapped in lines that are connected dry. I always seem to end up with a 10-20cm air pocket at the top of the input tube that I can't get rid of without following the steps below.

To prime using this setup I have to do the following (let's say I'm transferring from HLT to MT):

1. Connect input side of pump to HLT outlet.
2. Open HLT valve, MT valve and output valve on pump, allow water to flow from HLT, through pump, to output hose.
3. Before the water flows out the end of the output hose, raise the end of the tube to above the level of the liquid in the HLT. This forces liquid back up the line and pushes the air pocket up through the HLT.
4. Close the output valve on the pump.
5. Open the bleed valve on the pump slightly to allow any last remaining air in the pump head to escape. Catch and recycle any water that comes out (only a small amount).
6. Start the pump, open the output valve to the required amount and pump.

I must admit that when I go through these steps I get a good prime and an excellent, bubble free, flow from the pump.

The main problem I have is step #3. Getting rid of that air pocket in the line in this way seems dangerous. It wouldn't take too much of a lapse in concentration to end up with boiling liquid flowing out the end of the output tube and landing who knows where . Originally I thought I wouldn't need step 3 but so far I haven't figured out any other way to get rid of that air pocket.

So, am I missing something? How do you guys prime yer pumps?

 

[browndog]

Maybe I'm not understanding you right, but if you open the valves on the inlet and outlet sides of the pump, the water coming from the HLT should force any air in the pump out. Perhaps it is an oddity of the way you have done your plumbing.



Here is a pic of my plumbing, never had an issue with priming.

cheers

Browndog

 

[zephon]

Maybe I'm not understanding you right, but if you open the valves on the inlet and outlet sides of the pump, the water coming from the HLT should force any air in the pump out. Perhaps it is an oddity of the way you have done your plumbing.

That's how I expected it to work but when I do that I get the air bubble in the top of the inlet line.

Here's a crude diagram trying to explain it a bit better (pump is actually mounted vertically with inlet at bottom):

Seems like the flow of water isn't enough to push the air pocket down through the pump.

 

[Leigh]

I sometimes get a similar air pocket between my HLT and march pump.

Not enough pressure to sweep the tube of the air? I'm thinking of either putting a bleed valve above where the airpocket sits, or reducing the hose diameter to increase the pressure. Another thought I had was to fill the HLT from the bottom rather than the top.

 

[glaab]

Simma, is the valve on your HLT full bore or half bore?

 

[rwmingis]

Hi Simma,

How big's the tube coming from the HLT feeding the pump. A smaller tube will help with the air bubble problem (less flow required to fill the tube). Of course, this might slow down the pump due to additional friction losses.

Also, you should note that in the orientation that it's mounted on there may be a small air bubble that will take some time to come out. Not sure how big of a problem with will cause though. When I laid mine out, I had a height clearance limitation as it had to fit under the bed. As a result, I mounted my pump at 45 degrees (see sketch below). Then I realised that this is probably better for pump priming as the outlet is not on the side of the pump, but at 45 degrees from the side of the pump. When mounted with this outlet at top dead centre, it makes it easier for all air to get out.

Mind you, mounting with the centreline of the pump motor vertically may be better, I don't know.

Cheers,

Rob

 

[zephon]

Simma, is the valve on your HLT full bore or half bore?

The HLT valve is half bore. Valves on the pump are full bore. Inlet valve on MT is half bore.

 

[zephon]

Hi Simma,

How big's the tube coming from the HLT feeding the pump. A smaller tube will help with the air bubble problem (less flow required to fill the tube). Of course, this might slow down the pump due to additional friction losses.

The tube is a bit longer than a metre.

 

[Screwtop]

When I first got my pump I mounted it then removed the head, rotating it so the inlet was at the top it was then re attached to the pump, have never ever had a problem with priming, I let water from the HLT flow through the pump to the mash tun (gravity, into the tun via the ballvalve) until I see water entering he bottom of the tun, then switch on the pump.

Screwy

 

[rwmingis]

The tube is a bit longer than a metre.

Sorry simma, I mean the internal diameter. If the tube was bigger than 1/2 inch and you throttle the HLT it's a possibility

 

[zephon]

Sorry simma, I mean the internal diameter. If the tube was bigger than 1/2 inch and you throttle the HLT it's a possibility

The tube diameter is 1/2 inch.

Could this still be the issue given that the valve on the HLT is a reduced bore valve passing through a barbed hose tail?

 

[glaab]

The HLT valve is half bore. Valves on the pump are full bore. Inlet valve on MT is half bore.

try swap it for a full bore, I read somewhere about this problem before but can't find it.
IIRC the poster was told to put full bores only on the inlet side but the out side didn't matter

edit; but it might defeat the purpose if your hosetail has a small bore, I'll try find the thread

 

[RussTaylor]

try swap it for a full bore, I read somewhere about this problem before but can't find it.
IIRC the poster was told to put full bores only on the inlet side but the out side didn't matter

edit; but it might defeat the purpose if your hosetail has a small bore, I'll try find the thread

This one? http://www.aussiehomebrewer.com/forum/inde...showtopic=14882

 

[Thirsty Boy]

I get the odd air pocket trapped in between the MT and the march pump - I normally put water in the MT and run the hose from the pump into a bucket, let water run through and "squeeze" the air pockets in the silicon line, they then get forced through the pump by the flow - no more pockets and the valve gets turned off and the bucket emptied back into the MT.

The other thing you can do - or I have done anyway - is fill your HLT via the pump. I dont mean pumping water up to the HLT, I mean attaching the hose to the "out" side of the plumbing and forcing water back through the whole set-up. That way the line to your HLT fills from the bottom up. Then run a bit back through in the right direction. Air pockets forced out both ends that way.

 

[zephon]

Just a follow up for anyone who might search and find this thread.

I never did get the problem completely sorted, though I do believe it's related to 1/2 bore ball valves and/or the hose tails as it is less of a problem from my kettle which has a full bore ball valve.

As I don't really have the money to spend replacing fittings at this stage (too much beer to brew!) I am now priming all lines with water prior to starting the brew which leaves me with only tiny air pockets when switching hoses which are easily pushed out by opening the bleed valve on the pump outlet and recirculating about 300ml of the water/wort via a jug.

Tried it out with a brew yesterday and it performed flawlessly.

Thanks everyone for the advice.

Regards,
Simon

 

[Cocko]

Ok, I have tried everything..

March pumps do NOT work...

Is there a wiki some where I am missing?

If not, Can someone do a 'using a mach pump' article...

FARK!

 

[QldKev]

Ok, I have tried everything..

March pumps do NOT work...

Is there a wiki some where I am missing?

If not, Can someone do a 'using a mach pump' article...

FARK!

Pump below source vessel
Pump Inlet at the bottom
Pump Outlet to the top
If needed open valves and let pressure blow out air first.


If that is not working
What is you exact setup?
Maybe pics to show it

 

[kelbygreen]

I got one them cheap green pumps all I do is when the HLT is ready I open the tap on that and the MT and when it starts flowing into the MT by gravity I turn the pump on.

Whats not working for you??? you have to have the taps on remember

Edit: spelling. and yes what kev said

 

[Cocko]

Pump below source vessel
Pump Inlet at the bottom
Pump Outlet to the top
If needed open valves and let pressure blow out air first.


If that is not working
What is you exact setup?
Maybe pics to show it

I have it upside down.



KB is a carnt.

I will report back.


Cheers QK!

 

[the_new_darren]

Cocko,

When ever I have has problems I simply lay my "outlet" hose on the ground. TURN THE PUMP OFF. Once fluid starts to rum out of the hose by GRAVITY, turn the pump on.

Airlocks in the pump housing can cause problems.

Remember turn the pump off whilst trying to get rid of the irlock.

cheers

tnd