Controlling a vibe pump.

System

I have been asked too many times.  Can I use a dimmer to control my Vibe pump or other device.

SHORT ANSWER:  Dimmers are not all the same. Some act as a restive load OTHERS modulate the frequency.  Both will dim a standard incandescent lamp, as that is what they have been designed for.


I would not ever even consider using such a device.

LONG ANSWER:

Vibe pumps usually don't need high current  but it is not that simple as just any dimmer AND what works for one or some where else in the world, may not work for you.  (Voltage and Frequency are often at play).

A vibe pump is a combination of FREQUENCY ( that is what drives the rate of pulsing) and VOLTAGE which to some extent provides the magnetic force (That defines the force that the slug can exert).  Thus the one way valve/springs/ size of plunger and rate of cycling is all involved and the interaction between all variables is interesting.


So depending on how much control and what level of detail, a dimmer is at best a simple sea anchor in a storm. Some effect can be had; maybe more subjective than objective BUT better than nothing.  Then again what size/type sea anchor ?


Further more, on a few examples all I see is mismatched electrical items, poor workmanship and electrical safety totally out the door, all for a bit of what ?  Sorry, not worth the risk and little to be gained.


Where as when it comes to medical and lives at risk,  proportional control-valves with feedback AND note: the valves and controllers cost more than many coffee machines.  However the accuracy / linearity / and consistency is there to be had and often critical to the outcome, see the vid at about 2min.


In effect a OPV that could be PID controlled 


[embed=425,349]http://youtu.be/5jspoB6_YuI[/embed]

jimmytb

BES900 controls the vibe pump, possibly with a 50Hz pwm so it can still make full strokes just less per second?

UNM

I have a dumb question. Why would you want to? As in what is controlling pump intended to achieve? Pressure is managed by the OPV, temperature by the thermostat, pressurestat or PID. Flow  by the grind/dose/tamp. So what is left?

jimmytb

OPV doesnt manage pressure unless you play with the setting during the shot, it limits it.

derrilex

Playing with the opv during a shot is useless. The results will be different for each and every shot pulled using that method. Thats the whole idea of the opv - manage system pressure and bleed off that which is above the set value during the shot

jimmytb

on 1351147392:

Playing with the opv during a shot is useless. The results will be different for each and every shot pulled using that method.

That would be the point for some people, to try different profiles, for others to do preinfusion

on 1351147392:

Thats the whole idea of the opv - manage system pressure and bleed off that which is above the set value during the shot

The whole idea of it in the first place is to protect the boiler or HX section, if the manufacturers considered its function to be maintaining 9 bar during extraction they wouldnt set it to 12 at the factory.

derrilex

on 1351170695:

That would be the point for some people, to try different profiles, for others to do preinfusion The whole idea of it in the first place is to protect the boiler or HX section, if the manufacturers considered its function to be maintaining 9 bar during extraction they wouldnt set it to 12 at the factory.

Umm, nope. The pressure release or over pressure safety valve is there to protect the boiler in the event of overpressure situation. The OPV manages extraction pressure, not boiler pressure. They are set to 12 bar because that's what Italians think is the correct pressure for extraction.

jimmytb

I meant boiler in something SB or DB, or HX section otherwise. It is necessary to have a an opv or relief valve for safety and not only while brewing, during warm up for example, its my belief they have just been repurposed to limit extraction pressure

derrilex

I get your point but the opv only controls brew pressure. A pressure relief valve and OPV are two separate things. The first is for safety and the second is to manage or customise extraction pressure. :thumb: