Testing pressure release valves for La Pavoni and others

A haven dedicated to manual espresso machine aficionados.
User avatar
rpavlis

#1: Post by rpavlis »

It is highly important that safety pressure release valves work properly! The method I use works on most La Pavoni machines and many others.

I have a very simple technique that I use on my Europiccola machines:

Obtain a Presta bicycle tyre pump with an attached pressure gauge. (If your machine already have a pressure gauge any Presta bicycle pump would be fine.) These pumps are inexpensive, and anyone with a bicycle with Presta valves will almost certainly have one. Many, perhaps most, bicycle pumps have fittings for both types of valves anyway.

Remove the steam tip. On La Pavoni (and some others) the diameter of the steam wand is close to the size of a Presta bicycle tyre stem. You need not empty the reservoir to do this. The machine should be cold, however.

Attach the Presta connector on the pump to the steam tube. Open the steam valve. Pump air into the boiler watching the pressure gauge. When you hear air escaping from the pressure valve you have reached the release pressure.

Watch the pressure during the pumping stage--it should release at around 1.0. If it fail to open by 1.5 bar or so I would not raise the pressure much higher.

mathof

#2: Post by mathof »

What a brilliantly simple idea. I've just done your test, and my pressure valve releases about 1.5 bar. I now feel confident enough - having also inspected the valve and found it looking as good as new - to not worry further about it for now. From time to time, I'll disassemble it for inspection and do the bicycle pump test. Thanks very much for your help.

User avatar
allon

#3: Post by allon »

In the "and others" category, I've noticed that the male thread on my CMA lever's steam wand, sans tip, mates perfectly with the female thread on the air duster attachment for my air compressor, sans tip. This allows an easy way to pressurize the boiler to drain it, as well as to test the safety valve.

Note that air compressors may put atomized oil into the air, so you need an oil separator and air filter at the very least.
LMWDP #331

User avatar
atjong

#4: Post by atjong »

In a La Pavoni (at least in my Professional) you won't be able to completely drain the tank this way. The hot water pipe doesn't reach to the bottom of the tank, probably to protect the heating element.
Thanks for the tips though. They are very useful.

mathof

#5: Post by mathof »

mathof wrote:What a brilliantly simple idea. I've just done your test, and my pressure valve releases about 1.5 bar. I now feel confident enough - having also inspected the valve and found it looking as good as new - to not worry further about it for now. From time to time, I'll disassemble it for inspection and do the bicycle pump test. Thanks very much for your help.
I should add that after writing the above, I turned on the machine to pull a shot and found that the element would not switch on. I thought I had permanently damaged the pressurestat, but I found that by twirling the adjustment ring back and forth I could get it back in service. I guess the air pressure had jammed it in the off position.

User avatar
Chert
Supporter ♡

#6: Post by Chert »

allon wrote:In the "and others" category, I've noticed that the male thread on my CMA lever's steam wand, sans tip, mates perfectly with the female thread on the air duster attachment for my air compressor, sans tip. This allows an easy way to pressurize the boiler to drain it, as well as to test the safety valve.

Note that air compressors may put atomized oil into the air, so you need an oil separator and air filter at the very least.
Anyone have other tips for testing the pressure relief valve or more specifics about using the air compressor? If you put a refurbished machine into service you can buy a new certified valve, however, at least one post in these pages suggests testing the valve annually. So I wish to test both of my pressure relief valves for the commercial machines.

And thanks to Dr. Pavlis for the tip for the chrome peacock. I'll try that technique for the little machines that can.
LMWDP #198
thumbs up for 'helpful' and/or 'makes me laugh' which also helps

OldNuc

#7: Post by OldNuc »

In the U.S. these machines are not governed by the ANSI/ASME pressure vessel code. There are no testing or certification requirements.

User avatar
LaCrema

#8: Post by LaCrema »

Brilliant idea!

Just an FYI: 1 bar=14.504 psi and 1 bar=100 KPa for reference.
"Outside the box Barista."