erics wrote:Better recheck your measurements - it is a 3/8-19 BSP (British Standard Pipe) thread.

You are probably right - I just went off my receipt which is probably wrong.

Aloha. I'm relatively convinced my Silvia (v3) OPV is set too high and have constructed a PF pressure gauge via the design shown earlier in this post. Have a few questions before I begin testing and would be grateful for advice. I believe that Eric indicated that the pressure reading would be influenced by the cycling of the boiler heating element. Can someone explain why this is so ? Eric also indicated that one would have to choose whether to run the tests with the heater on or off. Wouldn't it be best to run the tests with the heating element on to simulate the pressure situation under normal operating conditions? I have the MLG (sp?) PID system installed and so my heating element kicks on constantly and certainly while pulling shots. Again, thanks for the feedback.

When the heating element is turned on, the voltage available to the pump is lowered and thus the pump doesn't have as much "muscle" . I forget how much pressure changes but it is inconsequential to the end product.

If you set Silvia's pressure to 9.0 bar with a blind filter, you will be very pleased with the results during brewing.

Makes sense. Mahalo for the quick response .

Well, had considerable difficulty w/ pressure testing due to leaks even with teflon taping. Don't want to tighten the 3/8" tee to the PF any tighter - i know the NSP threads are not an exact match. Best reading I could get before signficant leaking was 10 bar so I know I want to drop the OPV at least one bar. From this point on, I'll judge pressure by the taste and visuals using the bottomless PF. I understand that there is variation but can somebody recommend an approximate amount of turns to loosen the OPV valve to approximate a one bar reduction ?

andrewpetre wrote:I tried this today with some parts from the local hardware. I was surprised to find water squirting out around the top of the basket rather than sealing up.

This does not happen with the same handle when I use the blind filter. With the backflush (blind) basket inserted, it locks up tight when the pump is turned on, as I would expect.

Any idea why a standard basket would gush around the seal gasket in this particular application?

Also no leakage issues when brewing. If I choke the machine, it locks up tight - I never get any weird spillage like this.

I realize that the obvious answer is a hardened group gasket that could be replaced, but there are no similar issues when brewing or backflushing.

This is on an older Silvia.


ap

The rubber group gasket seals against the top of the basket's lip. There is no seal at all between the pf and the bottom of the lip. So it will leak unless you are extremely lucky or take steps to seal it, such as gluing the basket to the pf using RTV. Even that is no real guarantee as it wasn't designed to seal that way in the first place.

-Greg

Yup, I knew this was a possibility but I had seen a video or two posted on this site of the setup working and I thought I would gamble. Bummer for the $50 of plumbing and gauges, but really no big deal. In my case, I'm hesitant to try and tighten the NSP tee any tighter for fear of ruining the PF. Also, further tightening was difficult due to the positioning of the plumbing with respect to the backsplash wall. Nevertheless, I'm confident that I can dial in the OPV - right now, I get blonding and then spitting about halfway through the shot, even though the grind is pretty fine and the final shot volume is okay. I think I'll try backing the valve adjustment out half a turn or so to start and see what happens...

from what i see temperature has also some effect on the OPV performance, it looks like it is up to 1 bar, if comparing cold to hot (after idle at 208F for 2 hours.)



Temperature effect on OPV pressure in Rancilio Silvia V3

i don't think the drop is more then 1 bar. i need to clean and reinstall the OPV and rerun this test,

for sure as Eric said " If you set Silvia's pressure to 9.0 bar with a blind filter, you will be very pleased with the results during brewing. "

i will do it when machine is warm.

erics wrote:A good way (emphasis on "A") to build the PF gage is to screw a 3/8" street tee onto the PF and screw a 3/8" to 1/4" reducing bushing into the side outlet for your 0-300 psi oil-filled gage - http://www.gaugestore.com/prodinfo.asp?number=38305. Use brass fittings and two wraps of teflon tape on all of the male threads is sufficient. The bottom male thread on the tee can be capped off for future adventures. Yes, I have seen in previous posts where the use of a "non-filled" gage on a vibration pump machine has apparently worked with little or no needle flutter but the difference in cost between these gage attributes is small. Use a gage that has a known pedigree - yes it costs a little more but you will thank yourself.

Sorry to bring up this thread again, but does anybody know if the Silvia V3 Portafilter has a 3/8" screw on the bottom as well? I've gone to a number of hardware stores in NYC and nobody seems to carry liquid-filled pressure gauges or the pipings. Looks like I'm going to have to order it online, but I wanted to check the size of the Silvia V3 PF screw. Thanks!

The threads on the Rancilio portafilter are 3/8-19 BSPP which should have an OD of ~16.7 mm.