DIY PF pressure gauge

[HooHaw]

What do I lose if I buy a pressure gauge (with 8-10 bar as its midpoint) and screw it to the PF?

A poster on this forum did it but I couldn't find the thread again.

[admin]

What do I lose if I buy a pressure gauge (with 8-10 bar as its midpoint) and screw it to the PF?

A poster on this forum did it but I couldn't find the thread again.

So long as the threads match it shouldn't be an issue. I started with the "official" LaSpaziale Pressure Gauge I got from Chris Coffee. However, I dropped it and screwed up the guage. So I bought a replacement guage from Espresso Parts NW. The nice thing about the original is that it came with a thin copper tube bent back on itself to make the gauge right side up and closer to the viewer's eyes. Since I had this I used it after I purchased the replacement gauge. I'm not sure if this acts as an adapter or if the gauge would screw directly onto the PF. Since it was sold by EPNW for this purpose I suspect that it would screw directly onto the PF.

The key thing to remember is to fill the PF from the hot water dispenser befor you lock on the PF. Otherwise, the trapped air with give you strange readings. The most common sign of this problem is for the pressure to go up to where you'd expect, pause there briefly, then continue up to 15+ bar.

[HooHaw]

Thanks Chas. I remember reading about the trapped air causing pressure reading problem.

[HooHaw]

I've put together a PF pressure gauge but do I use the measurement with a PF basket in or without?

If I place a double basket in the PF the measurement the pressure gauge gives me a steady reading (+/- 1/5 BAR). BUT if I don't include the basket the pressure ramps up to ~9 BAR and, after a second or two, starts climbing again to the limit.

[BillK]

I've put together a PF pressure gauge but do I use the measurement with a PF basket in or without?

If I place a double basket in the PF the measurement the pressure gauge gives me a steady reading (+/- 1/5 BAR). BUT if I don't include the basket the pressure ramps up to ~9 BAR and, after a second or two, starts climbing again to the limit.

I am surprised that by using a basket you don't get leakage between the lip of the portafilter and the bottom of the basket lip. I do my measurements with no basket - I just tighten the lip of the portafilter up against the gasket.

I fill my portafilter with water before locking it in place, and I get a rapid, solid ramp-up to a steady state value.

As an aside, I used the same basic setup (same gauge and gauge connection to the portafilter) for my old hx machine that had a vibe pump. The difference in pump pressure fluctuations is striking. With the vibe pump, there was so much vibration of the gauge needle that all I could see was a blur, and I had to take the midpoint of the blur as the reading. With the rotary pump and the same gaugue setup, the needle is rock solid. Some people claim that the vibe pump vibrations make better crema. I have not experienced this. I see absolutely no downside to a rotary pump versus the vibe pump, except for initial cost and machine weight.

[wgaggl]

What Bill said:
Fill your PF gauge with water first. Preferable use hot water from your water spout to match temperatures.

It has been discussed in several messages on this board, that some have seen climbing pressure. This can most likely be attributed to air bubbles expanding when been heated. So you should make sure that your PF gauge's temp is close to brewing water and as little air as possible in it (sometimes the first reading takes off 9+bars even when filling the PF with water first, but when you stop the pump, most of the air is released by the three-way valve, so when you engage the pump again, the reading is more stable).

Wolfgang

[HooHaw]

Bill, yep did get leakage with the basket but the pressure held steady unlike the no basket method.

Wolfgang, I did fill the PF with water.

BTW, I did this while the S1 was cold. I didn't think temperature would matter much.

[HooHaw]

Thinking about what you wrote Bill, I went back and re-did the measuring and this time I cinched the PF without basket as tight as I dared and also did while things were at working temp. Walla! No leaks and the gauge went to 9 BAR, stayed at 9 BAR. Another go and still stayed at 9 BAR. This is to easy... except for the hot surface. :(

Anyway, I adjusted it down to about 8.5 BAR and take it from there. That is... until the coffee arrives, I've run out!

Thanks guys! :D

[daerider]

Thinking about what you wrote Bill, I went back and re-did the measuring and this time I cinched the PF without basket as tight as I dared and also did while things were at working temp. Walla! No leaks and the gauge went to 9 BAR, stayed at 9 BAR. Another go and still stayed at 9 BAR. This is to easy... except for the hot surface.

Anyway, I adjusted it down to about 8.5 BAR and take it from there. That is... until the coffee arrives, I've run out!

Thanks guys!

HooHaw,
Did you take your pressure reading with or without flow through the portafilter? It has been my experience that you might need to adjust the static pressure reading 0.8bar higher to account for a flow rate of ~ 1.5 oz in 27sec.

[HooHaw]

Nope. After cinching it tight there was no leak hence no flow. So that means if I'm reading 8.5 BAR I actually have ~9.3 BAR. Does that La Spaziale PF gauge allow flow through the PF?

[daerider]

Nope. After cinching it tight there was no leak hence no flow. So that means if I'm reading 8.5 BAR I actually have ~9.3 BAR. Does that La Spaziale PF gauge allow flow through the PF?

Just the opposite! I have not tested this on my S1 yet. But on my oscar I have a procon pump externally mounted with a pressure gauge at the outlet side that goes to the machine. I have my pressure set to 8.5 bar messured while extracting a 2.0oz restretto from a La Marzocco triple basket with 21g of coffee in ~30s. If I put a pressure gauge on the PF with the same settings, I now read ~9.25bar on both of the gauges with no flow.

[HooHaw]

Well, I can't test leaking versus no leaking readings, I'm going on a vacation.

Dang! No espresso for 2-weeks!

[sraike]

So what is the consensus to set the pressure at with no flow? That is how most of us will be checking it. I'm thinking the manual said beween 8 and 10 bar. I checked mine when new and it was right on 7 bar. Took about 2 turns of the adjustment screw to get it up to 9 bar. I notice at 9 bar I hear more water from the pump bypass entering into the tray.

[HooHaw]

I didn't know the group pressure regulator 'leaks' water to regulate the pressure? I know that the Expansion valve can leak when the line pressure is high.

[daerider]

So what is the consensus to set the pressure at with no flow? That is how most of us will be checking it. I'm thinking the manual said beween 8 and 10 bar. I checked mine when new and it was right on 7 bar. Took about 2 turns of the adjustment screw to get it up to 9 bar. I notice at 9 bar I hear more water from the pump bypass entering into the tray.

When I purchased my S1 from Chris, I asked him to set the pressure at 9bar. When I checked the measurement with my portafilter gauge set-up with no flow out of the portafilter or any water coming out of the pump by-pass valve, I had a reading of ~9.8bar on the portafilter mounted gauge. Since the pump is mounted inside the machine and there is not an easy way to mount a pump pressure gauge at the pump outlet like I did with my oscar, I will have to create some kind of flow valve at the portafilter mounted gauge to get an accurate measurement with the flow rate that I am targeting. I will probably just put 3/8 tee on the end of the portafilter, screw the gauge in one end of it and block the other end with a brass bolt that I can tighten and loosen to adjust flow rate. If I decide to get really fancy, I could always plug the end with a brass plug and drill and tap a hole for a needle valve assembly which would give me a finer range of adjustment.

[daerider]

So I decided to go to home depot this evening and build a crude flow regulator.

1 - Rain Bird pressure gauge ($9.00)
1 - 3/8" female tee ($3.00)
2 - 3/8" to 1/4" male reducer ($2.00)
1 - 1/4" drain valve ($2.00)
1 - roll of teflon tape ($1.00)

The results I got were interesting. With the drain closed I measured a static pressure reading of 9.5bar. With the drain valve adjusted to allow a flow rate of 1.5oz in 25seconds I measured a reading of ~9.0bar. With the drain valve adjusted to allow a flow rate of 2.0oz in 25seconds I measured a reading of ~8.75bar. I hope these measurements help. Keep in mind that they are a first attempt and have not been verified to any degree of certainty, but I thought they would be interesting to post. I took some pictures of the flow regulator but I'm not quite sure how to post them to the site. If anyone is interested in them, I would be happy to send them out....

[sraike]

When I purchased my S1 from Chris, I asked him to set the pressure at 9bar. When I checked the measurement with my portafilter gauge set-up with no flow out of the portafilter or any water coming out of the pump by-pass valve, I had a reading of ~9.8bar on the portafilter mounted gauge. Since the pump is mounted inside the machine and there is not an easy way to mount a pump pressure gauge at the pump outlet like I did with my oscar, I will have to create some kind of flow valve at the portafilter mounted gauge to get an accurate measurement with the flow rate that I am targeting. I will probably just put 3/8 tee on the end of the portafilter, screw the gauge in one end of it and block the other end with a brass bolt that I can tighten and loosen to adjust flow rate. If I decide to get really fancy, I could always plug the end with a brass plug and drill and tap a hole for a needle valve assembly which would give me a finer range of adjustment.

daerider, that sounds like an excellent way to get a dynamic pressure reading. I bet you could simulate 2 oz of water flow in say 25 seconds with a needle valve. I just rechecked the static pressure on my S1 and somehow it dropped to 8. Was 7 bar as rec'd new. I had adjusted it to 9 even and I know I locked the lock-nut down good. Will have to check into what's going on this weekend.

Stu

[TruthBrew]

Sorry to bring this up again but....

I really would like to test my group pressure, but don't really care to drop $50+ on the PF with gauge.

Are there any other options? I have an extra PF already, but the gauges seem to be approx $45 on their own anyway. Any ideas on saving money?

[bobroseman]

Sorry to bring this up again but....

I really would like to test my group pressure, but don't really care to drop $50+ on the PF with gauge.

Are there any other options? I have an extra PF already, but the gauges seem to be approx $45 on their own anyway. Any ideas on saving money?

daerider did it for $17. Just check a couple of posts up from yours.

Bob

[Barry]

Sorry to bring this up again but....

I really would like to test my group pressure, but don't really care to drop $50+ on the PF with gauge.

Are there any other options? I have an extra PF already, but the gauges seem to be approx $45 on their own anyway. Any ideas on saving money?

You can get all types. They range from $8.00 - $150.00. Everything you see on the web for this purpose is the $8.00 variety.

http://www.gaugestore.com/

[Barry]

A number of people of commented on DIY pressure gauges. Having purchased one from Chris and never being particularly fond of it, I decided to build my own. All the parts with the exception of the actual gauge were purchased at HomeDepot

1- 3/8" Brass Female T about $5
1 -3/8" to 1/4" Brass Female reducer $1.50 (attaches gauge to the T)
1- 3/8" to 3/8