On Vibe pumps and OPV's

[John F]

OK engineer types tell me how this works...

An unregulated vibe pump delivers X flow rate at Y pressure.

The use of the OPV allows us to set the pressure to a desired 9 bar setting by shunting the excess water back to the reservoir. 

The shunted water is subtracted from the through the puck volume but it allows the pump to operate at it's full capacity.

Would a regulator/valve serve as an OPV if it was placed before a pressure gauge? Could you simply restrict flow to 9 bar or would the pump explode from flow restriction? Would simple flow restriction post pump even be adequate to control brew pressure if the pump is unharmed?

Secondly in the standard OPV set up how about that shunted water...what effect is it having on the water debit at/through the puck?

I'm guessing there is a reason they use redirection OPV's instead of valve/gauge regulation and I'm curious if it's about pump safety or shot quality....or neither. 

[MMW]

I had a long thing written out here, but then I reread your question.  The answer is no if I'm not totally off on how the vibe pumps work.  They should move a given amount of water at a variable pressure (within reason) so if anything you'd be creating higher pressures at the pump with a restriction.  I think you'd burn up the solenoid in those little buggers before you managed to blow one up, though.

I reserve the right to be found totally wrong here, however.

[John F]

They should move a given amount of water at a variable pressure (within reason) so if anything you'd be creating higher pressures at the pump with a restriction. 

I don't mind about higher pressure at the pump (if it won't break stuff) just the puck and if water debit would be adequate by restricting flow to obtain 135psi/9bar.

I'm wondering if I can take the outline from a vibe pump and install a valve as a flow regulator and a gauge right after it to measure adjustments/restriction. I'm almost positive it will be adjustable to bar pressure but the effects of doing it are what I have no idea about.

hampered water volume at the puck
Back pressure at the pump causing a mechanical failure
It might work

I'm unsure...

Meanwhile all the OPV is doing is diverting the excess pressure HOWEVER the by product is a loss of water volume at the puck that is diverted back to the reservoir. It's this bit that has me wondering. The only advantage I see is that it allows the pump to run full output rather than have to wait for flow to pass a regulator valve inline. That may be VERY important or not...I'm clueless.

   

[bobvilax2000]

One thing to think about is that when a machine is heating up is that it creates pressure in the lines connected to the boilers. One function of the opv is to let that pressure out. When I upgraded my Brewt's vibe to a rotary I had an opv in the line for safety, but I accidentally had it closed on my first heat up. Heard quite a lot of hissing from the next room. I now have my rotary set to the brew pressure and the opv to about twelve and it drips to the reservoir at every warm up.

I don't think that a vibe pump much likes back pressure as they're not meant to deal with it, but if you do try the regulator valve keep the warm up pressure in mind.

- -Barrett

[John F]

I don't think that a vibe pump much likes back pressure as they're not meant to deal with it, but if you do try the regulator valve keep the warm up pressure in mind.

My current pump has a hi limit valve direct mounted that I can not remove. So if all else fails this dude should open to protect the pump.

[bobvilax2000]

Alright, cool. As long as there is someplace for warm up pressure to go so that no hoses blow. What machine is this, by the way?

- -Barrett

[mp]

Alright, cool. As long as there is someplace for warm up pressure to go so that no hoses blow. What machine is this, by the way?

- -Barrett

Barrett ... he has a Gaggia Carrezza/

 

[bobvilax2000]

Doh! You mean like the several page thread started by... 
You can't expect me to keep track of these things. 

- -Barrett

[J.Jirehs Roaster]

Doh! You mean like the several page thread started by... 
You can't expect me to keep track of these things. 

- -Barrett

Yes we can!!... their will be a test later!!!   

[mp]

Doh! You mean like the several page thread started by... 
You can't expect me to keep track of these things. 

- -Barrett

Yeah ... that is correct.

Just pretend you are a dog chasing a rabbit.

 

[J.Jirehs Roaster]

Doh! You mean like the several page thread started by... 
You can't expect me to keep track of these things. 

- -Barrett

Yeah ... that is correct.

Just pretend you are a dog chasing a rabbit.

 

and try to keep the scorpion off your back 

[mp]

and try to keep the scorpion off your back 

Or maybe use the scorpion to sting the rabbit that way it will slow him down for the chase.

 

[Tex]

OK engineer types tell me how this works...

An unregulated vibe pump delivers X flow rate at Y pressure.

The use of the OPV allows us to set the pressure to a desired 9 bar setting by shunting the excess water back to the reservoir. 

The shunted water is subtracted from the through the puck volume but it allows the pump to operate at it's full capacity.

Would a regulator/valve serve as an OPV if it was placed before a pressure gauge? Could you simply restrict flow to 9 bar or would the pump explode from flow restriction? Would simple flow restriction post pump even be adequate to control brew pressure if the pump is unharmed?

Secondly in the standard OPV set up how about that shunted water...what effect is it having on the water debit at/through the puck?

I'm guessing there is a reason they use redirection OPV's instead of valve/gauge regulation and I'm curious if it's about pump safety or shot quality....or neither. 

The volume through the pump is the same. The OPV just redirects excess pressure/volume to a different output. Here's a link to a short blurb that explains how the OPV works.

[John F]

The volume through the pump is the same. The OPV just redirects excess pressure/volume to a different output.

I got all of that but what happens if you put a regulating valve in place of the OPV?

That is what I'm trying to figure the viability of.

It would allow me to set the brew pressure at 9 bar but I'm not clear on the effect it will have;

a) on the pump.
2) on the water volume at the puck. On this point the OPV in normal operation is shunting the water as well so it could be a wash...

 

[John F]

Alright here is an example....expansion valve.

http://www.chriscoffee.com/products/home/isomacparts/replacementexpansionvalve

It looks like what I am suggesting to install prior to a pressure gauge and as the description says it can do adjust it down to 9 bar.

This valve does not look like it has a line that is going to return water to the tank...just regulate flow. I'm going to see now what kind of pumps Isomac uses but if it's Ulka vibe pumps the idea is looking more possible. edit- they use 52 and 41 watt vibe pumps...

The only difference I can figure out now is in allowing the pump to run full flow or restricting it. The coffee might be getting the same treatment either way so it just comes back to the pump and if restricting flow will hurt it or not. As it is now what happens if I choke the machine? The pump is getting no flow and that does not harm it.....I hope somebody that knows more about vibe pumps tells me something before I burn up a pump.     

Another edit- email sent to Chris @ Chris coffee. I dont' know if he answers tech questions but if this works I will buy it from him. Looks super straight forward to install because of the inline tee just waiting to be spliced in..