Pump seems slow, what is proper flow without coffee?

[duke-one]

Hello: Is there a proper time for an amount of water to flow from the brew head without coffee to test the whole system? I am not sure there is enough water flowing (pressure is good), the stream seems a little "weak". Could be an enlarged prostate? I've checked the incoming line, plenty of flow there. Also have pulled the "jet" it was clear.
Thanks, KDM

[HB]

I don't know the particulars of your machine, but more than likely your Astoria Compact has a gicleur (orifice) in the grouphead that restricts the flow for preinfusion. Perhaps it's clogged? What kind of pump does it have (rotary, vibe)? If it's the typical Ulka EP5, Eric provided some good background information in The point of adjusting the OPV, excerpted below:

To the best of my knowledge, all Silvia's are fitted with the Ulka EP5 pump and the flow characteristics of that pump are as shown below:



I realize that the definition of a double-shot is a debatable (and very rightly so) subject in and by itself but, strictly for discussion purposes, let's assume that a double-shot puts 60 ml of espresso (including crema) in a cup in 25 seconds when the puck is subjected to a pressure of 9.0 bar. If you look at the graph of the Ulka pump performance, you'll see that it is capable of fufilling this requirement and when it does so, there will be flow in the OPV line back to the tank. Naturally there are tolerances associated with pump manufacturing and, after so many years of operation (even in a home environment), some pumps are a little more tired than others. However, the solid line does represent a production average and the dashed lines represent min/max allowable to get the pump out the door.

[another_jim]

The typical diagnostic is to run exactly 10 seconds worth into a measuring cup (no pf, no obstructions, no cooling flush). Anything more than 2.5 ounces is fine. If it's less than 1.5 ounces, you have a problem. From 1.5 to 2.5 ounces is troublesome, but some machines with very fine restrictors and vibe pumps are in this zone when everything is OK.

[duke-one]

Jim: Thanks this is exactly the data I wanted. My machine is warmed up for this mornings coffee, I'll get my measuring cup and use the microwave for the timer.
Duke

[duke-one]

All: I did the flow test as suggested by another_jim and it seems to be at the bottom of the spec. Where to look next? I've pulled the bell and checked the passages in the shower head and the thingee above that. Also pulled the "jet" and screen, it was clear. The machine had sat for a couple of years, that could be a clue. It was not drained but the supply was shut and pressure bled off. We have real good water here (East Bay of San Francisco) so wouldn't think mineral deposits were in play. Picture of group below.

Thanks in advance to all for help, KDM

[cannonfodder]

Is your machine a vibe or rotary pump machine?

[duke-one]

It is a rotary compact machine. I believe it is a full commercial machine, it weighs 120 pounds.
Pressurestat control, automatic dosing (runs a programed, by me, amount of brew water) if that is the proper word for it.
Duke

[erics]

The number that Jim mentioned (2.5 ounces in 10 seconds) equates to 15 oz/min which equates to ~ 444 cc/min. This would be proper flow for a "E-61-ish" type machine equipped with a vibration pump whereas yours has a rotary pump. Attached is a chart which duplicates the capacity curve that Dan provided but also includes the capacity curve for the smallest Procon (rotary) pump typically(?) fitted to 1-group machines.



Exactly how much flow do you get out of the group in 10 sec?, in 30 sec? in 1 minute?

Are you regulating the line pressure to any specific value?

The TYPICAL flow from a rotary pump through the grouphead should be around 30 ounces/minute (my guess).

[duke-one]

Eric: I get four ounces in thiry seconds, is that enough? I haven't used machine for a couple of years so memory of original flow is weak. Duke

[erics]

I know I'm gonna sound crazy here but are you sure this machine has a rotary pump? I understand that "rotary" is in the name designation but this is espresso and, well . . .

When you first said that the pressure was OK, were you referring to the boiler pressure (should be in the range of 1.1 to 1.3 Bar) or were you referring to brew pressure (should be in the range of 8-10 bar for starters?

Regardless of what type of pump this machine has, 4 ounces in 30 seconds is indicative of a problem. Is there any flow from the drain connection of the three-way valve while you are running the pump?

I would start with the three-way valve. Slide the solenoid off the valve body (keep the wires attached) and unscrew p/n C.166. Now run the pump and see what flow you get in those same 30 seconds.

More later depending upon results.

[duke-one]

Eric: The machine has a rotary pump, water cooled motor for the pump. I may not be an espresso machine expert but have been an electrician for thirty or so years so I know machinery in general. I will try your suggestion next. There is no bypassing from the three way valve while running. All the pressures seem in the right ranges, brew at just short of 9bar. I don't get around too well so my apologies for the long time for my replies.
Thanks, Duke

[erics]

I offer apologies for the "are you sure . . .?" quiz.

In my mind there is a restriction somewhere in the flow path and the fact that you are reading ~ 9.0 bar tells me that the pump relief/regulating valve is working just fine.

Here's hoping the three-way valve is the culprit.

[duke-one]

Eric: Something I noticed this a.m.: the gauge read full pressure while the pump was running without the filter basket in place, shouldn't it be lower without the resistance of the coffee and filter? This might point to some part of the system, no?
Duke

[HB]

...the gauge read full pressure while the pump was running without the filter basket in place, shouldn't it be lower without the resistance of the coffee and filter?

No, a rotary pump's flow rate is high enough relative to (espresso friendly) flow rates through the gicleur that the full pressure reading is normal.

[duke-one]

Hi All: I now have had the three way valve off and opened up: all looks ok, passages are clear, armature is free. While it was off I turned on the water and got a steady slow flow if that means anything. After putting it all back I ran it and got the same flow: 4 oz in 30 seconds. I'm just about ready to call for a service call from Mr. Espresso where I bought the machine. On the other hand it seams to be making good coffee so...............
Duke

[erics]

While it was off I turned on the water and got a steady slow flow if that means anything.

It means a lot, especially if the flow was substantially greater than 4 oz in 30 seconds as that would indicate there is a restriction downstream of the solenoid valve.
If you ran the pump with the solenoid valve unscrewed and got, say, 10 (or more) oz in 30 seconds, that says a lot.

I'm just about ready to call for a service call from Mr. Espresso where I bought the machine. On the other hand it seams to be making good coffee so...............

That's a big plus however I believe a call in to Mr. Espresso would reveal a lot. I may be a little naive here but I would like to think that they could answer the flow quantity question in about one minute and the totality of their response would be most interesting.

[duke-one]

Got it! It was the jet and it was partly clogged. When I first had it out I looked though it it was open and I thought; good enough. Ha. Used the leg of a LED, it fit and is square in cross section so it would scrape the bore. As soon as I did this and looked up to the light I knew I had it licked. The flow is now 12 oz in 30 seconds, three times the original test. Hat tip to the tech at Mr. Espresso in Oakland California for his free advice over the phone and thanks to all at H.B. who responded to my posting. This could be the cause of low flow in other machines, pass it on.
Thanks, Duke