Speedster water path - Page 6

#51: Post by **RapidCoffee** » January 22nd, 2009, 6:23 pm

j7on wrote:"Manual Brew Pressure Profiling"...

sweaner wrote:Along a similar line, could a rotary pump be adjusted during a shot? Start with low pressure and slowly build the pressure as one sees fit?

This is actually very easy to do on a plumbed machine. Get rid of any pressure regulator on the water line to the machine, and readjust the maximum pump pressure as necessary. Now you can manually adjust the brew pressure by opening/closing your cold water tap in the kitchen sink. I played around with this some last summer.

#52: Post by **j7on** » January 23rd, 2009, 6:50 am

erics wrote:Espresso machine pumps would be classified as positive displacement pumps, most definitely NOT best started with the shut-off valve closed. To the best of my knowledge, all positive displacement pumps have some sort of protection (OPV, by-pass valve, relief valve, etc.) to account for this condition.

OPVs & by-pass valves are on the vibratory pumps cuz they push out like 15bars and are not adjustable, adjusting is done with OPVs.

There is no protection on HX lines or groupheads, double boilers, the brewboiler does not have a protection valve(and if they did they would be set above 9 bars).

On a regular startup in a brew there will be that 9bar pressure and basically NO water flowing anywhere for sometime before the water finds it way through the puck, and even then, we are talkin espressos here, there is so little water coming through, the pump is always pushing full on(unless you do a cooling flush...

Have anyone tried varying the power to their rotary motors and by doing so, being able to adjust the pumps flow?
My guess is that it will not run at all after a powerdrop.?

#53: Post by **ira** » January 23rd, 2009, 11:36 am

Most of the rotary pumps I've seen are AC motors. If you really want to control the speed you'd likely want a 3 phase AC motor and a fancy motor controller. I've got one at work that controls a 20 HP motor in .1hz steps from 0 to 60hz and I control it via a program running on a PC. Bit of overkill, but you get the idea. Because of all the recent concerns about energy savings there are lots of $5 microprocessors dedicated to doing exactly that.

Ira

#54: Post by **j7on** » January 28th, 2009, 6:05 pm

Well, thought about the manual valve some more and it probably will not work...

For instance, the E61 has a miniscule hole(jet) where water enters the grouphead and its still 9bar, so.. it would have no difference how small or big the path at the valve is as long as the line is pressurized.

I looked around at scooter parts and other electric vehicle parts resellers for motor controllers until i realized it is also called VFD(variable frequency drive).

Here:
http://en.wikipedia.org/wiki/Variable-frequency_drive

Must look for one and see if it actually works