Why doesn't brew pressure return to zero + installing gauge

[Kristi]

I've been wanting to add a brew pressure gauge to my Bric. (If anybody's done it, please tell me where you did it.)

After trying to find a fitting that would go between the line, and where the line joins the HX... There's an elbow there. It's easy to screw into the elbow, but nothing I've found will adapt to the flare fitting that's on the end of the copper tube that screws into the elbow.

So I chopped the plastic tube after the pump and put a T in there with a gauge on the end. Of course it vibrates like crazy. The center of the blur is probably the brew pressure. But the part that interested me is that (using a blank in pf) when I put the lever down and it blows the excess head pressure out the bottom, the gauge stays on 8 or so and -slowly- (minutes) goes down. If I raise the lever slightly, that pressure is instantly bled to 0. I had been assuming that when you lower the lever that the pressure of the whole line would go to roughly 0, or, I suppose, boiler pressure. I wonder why it stays up near brew pressure?

I guess that was question 1!

Question 2 is "is there a way to damp out the vibration to the gauge (this IS a vibe pump, after all)?

and question 3 is: Would I be any better off, vibration wise, to insert a T up where the line goes into the HX (probably by cutting the existing flare fitting and coupling to that copper tube with a tube fitting.)

tia!
Kristi

[HB]

#1. Sounds normal. The valves are alternatively open, so the pressure isn't released completely from the system when the lever is straight down. Were that not the case, the HX would boil dry.

#2 and #3. All the machines I've seen have dry gauges and eliminate flutter by coiling very thin 1/8" OD tubing several times to act as dampeners. Manufacturers install the tee further downstream to reduce the effects of the vibration pump's pulses and the thin tubing dissipates heat that would otherwise be transmitted to the gauge.


Brew pressure gauge tee on the Andreja Premium at the heat exchanger exit

Alternatively you can install a snubber and wet gauge for good measure. I had a dry gauge and snubber on hand for this installation. The gauge buzzes a little, but it's a fast install and temporary (i.e., I install a temporary brew gauge if the evaluation machine doesn't have one, e.g., the Cimbali Junior, Giotto Premium, etc.).

[Kristi]

THANKS! Great animation!

I do not see the snubber in the lower pic - is it visible?

back of my machine. I tapped in the plastic tube after the pump. Would it be that much better to tap in top left below the elbow (that corresponds to the place on your Andreja pic). In any case I could easily order some 1/8" fitting capillary tubing. One of my 2 gauges has 1/4" fitting so the snubber would easily work on that. I think for my first attempt I'll order a snubber and some capillary tubing and try that on the tap I have now. If it still is bad I'l give up and cut the tubing just below the elbow and put the whole contraption there.

I do not know the difference between a wet gauge and a dry gauge or how I would tell. One gauge is from
http://www.1st-line.net/cgi-bin/c...em=V512&type=store
without the elbow adapter for the pf.

The other is similar to a Campbell 0-200psi , picked up at Home Depot in the compressor section.

Both have gotten wet in their innards and neither seems affected.

Initially this will look like a temporary setup because the Bric with that high garbage can case back is too high to fit under my kitchen counter, so it is sans back. The main prob with this is the water reservoir is not held in and when I pick up the Bric to turn it around to work on something, I forget about the reservoir 50% of the time and that's 3 liters on the floor - one way to clean the floor!


EDIT - I assume that's an 1/8" fitting on the capillary on the Andreja?

[HB]

I do not know the difference between a wet gauge and a dry gauge or how I would tell.

Google is your friend on the Internet. However, this one last time: Selecting a pressure gauge... When selecting a pressure gauge, it is important to consider the following factors to insure safety and accuracy.

Liquid Filled Option
Liquid filled gauges help absorb vibration and pressure spikes, increasing the service life of the gauge. The dampening action of the liquid reduces pointer flutter and lubricates the internal parts, dramatically reducing wear in the movement. Glycerine is the standard fill fluid and provides the best performance in most applications. Silicone has a low viscosity and works well when extreme temperature fluctuation or icing is expected. The fill liquid must be compatible with the gauge application.

The gauge you linked is not filled with glycerine.

I assume that's an 1/8" fitting on the capillary on the Andreja?

Yes, as I already noted in my first post.

[Kristi]

Kristi wrote:
I do not know the difference between a wet gauge and a dry gauge or how I would tell.

Google is your friend on the Internet. However, this one last time: Selecting a pressure gauge... When selecting a pressure gauge, it is important to consider the following factors to insure safety and accuracy.

thanks.

Liquid Filled Option
Liquid filled gauges help absorb vibration and pressure spikes, increasing the service life of the gauge. The dampening action of the liquid reduces pointer flutter and lubricates the internal parts, dramatically reducing wear in the movement. Glycerine is the standard fill fluid and provides the best performance in most applications. Silicone has a low viscosity and works well when extreme temperature fluctuation or icing is expected. The fill liquid must be compatible with the gauge application.

The gauge you linked is not filled with glycerine.

That's fantastic info. Gaugestore.com has a $25 min so I can't order just the snubber, so I ordered the capillary tubing and will try that first. if not enough, then I will get snubber and gauge from gaugestore.com.

I assume that's an 1/8" fitting on the capillary on the Andreja?

Yes, as I already noted in my first post.

you said the tubing was 1/8", I was asking about the fittings on each end of the capillary tubing - they look like "1/8" fittings".

Thanks!!!

[Kristi]

The fittings on the end of the capillary tube were 3/16" compression.

The capillary tube totally removed the visible needle vibration.

I notice with -NO PF- the pressure rises to 4.25bar over about roughly 1 sec.
EDIT - this value goes down to 3.75 or so as OPV setting is increased to 9.5 bar...

I assume this is the result of the gicleur?,

and the 1 sec is the time it takes to fill the infusion chamber, then water starts flowing through the shower screen?