gajetjunkie Senior Member Joined: 14 Nov 2003 Posts: 139 Location: Houston , TX Expertise: I love coffee
Espresso: La Valentina Semi-auto ,... Grinder: Mazzer Mini ,Capresso... Vac Pot: Not yet , French Press Drip: Technivorm Roaster: Behmor , SC/TO
Posted Wed Aug 11, 2004, 12:44pm Subject: Cheap pressure gauge!
I needed to check the boiler pressure on my Expobar. I'm pretty tight/cheap , so I made a homemade temporary pressure gauge to dial in my Pstat.
You can get everything at the auto parts store. I bought a round tire pressure gauge , a short length of fuel hose , you could use a piece of HP air hose , and 2 hose clamps. I just put it all together and attached it to my steam wand as you see in the pic below. Then just open the steam valve to read the pressure and dial in the Pstat.
When I first checked the boiler pressure it was at 12psi/.827bar which is too low for me. It only took about one full turn clockwise on the pstat and that brought the pressure up to 15psi/1.03bar. My expobar has the pstat with the thumbwheel adjustment not the small brass screw. The shots improved and I noticed that I had more steam for frothing.
The top of the cycle on the Expobar machines is the point when the boiler light goes off. This will be the point where the pressure is highest. Another thing you can check is the deadband of the p-stat. This is the difference between the highest and lowest pressures of the boiler cycle. It should be somewhere around 0.2Bar if your p-stat is operating correctly. Yes, the steam valve is left open during the entire process. Raising the boiler pressure will improve the shots if they are sour and the temp is too low. On the other hand, lowering the p-stat setting will improve the shots if they are bitter because of too high of a brew temp.
i have had my second pulser for a few weeks now... and the shots are amazing right out of the box... the first one had a bad p-stat... i am very interested in making that Cheap pressure gauge... thanks
----- "Some people spend an entire lifetime wondering if they made a difference in the world. But, the Marines don't have that problem." Ronald Reagan, 1985 -----
Very cool - doe you think a tire pressure guage is precise enough at low pressures to give an accurate result? My guess they are calibrated to be their best at 20-30lbs pressure. I may look around to see if there are cheap low pressure guages avail. Your idea is teriffic !
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