Coffee Sensor AirBuster® release valve and chamber for La Pavoni Lever group heads

Coffee Sensor AirBuster® release valve and chamber for La Pavoni Lever group heads offers the user:

1. Higher yield volume by flushing out the trapped air from inside the chamber and PPK shaft;
2. No spongy start pulls (immediate pressure feedback on the lever arm);
3. No spongy end pull;
4. Safe and fast PF release (no sneeze) right after your extraction;
5. More accurate control for pressure/flow profiling kit;
6. Non electrical and no batteries needed for operating the Air Buster;
7. Fully automatic – no manual opening or closing of the valve needed;
8. Easy installation (addon on our piston pressure kit is easier then ever);
9. Stainless steel parts and brass valve, all food grade materials;
10 Back acorn nut lets you use our provided silicone tube for back flush (this is the first time when this is possible on a La Pavoni machine);
11 Provided pipette lets you remove the waist water from inside the collector chamber.

Also, most recent discoveries from Bong are that:
1. You can insert the portafilter in the group head and then IMMEDIATELY lift the lever without worrying that the puck will be raised.
The air from above the puck will be released with the help of the valve instead of the coffee puck suction that usually can happen.
2. No worries of doing fellinis or 2nd pull. Good for those who love the traditional Italian 14g in 60ml out.

The product is created by our special group:
Bong Juachon – Concept idea and design;
Tudor P. from Coffee Sensor – manufacturer / material testing and industrial support;
John Michael Hauck – Tester / Informational, pictures and videos support / CAD support.

Bong J. states clearly, during his volume comparison with and without Air Buster:
The effect of preinfusion / puck saturation was eliminated by simulating a totally saturated puck by mounting a valve that opens at 6bar pressure:
Ave volume with AirBuster® = 43g
Ave volume without AirBuster® = 29.7g
Ave volume % gain = 44.78%

Coffee Sensor AirBuster® release valve and chamber for La Pavoni Lever group heads works only with our original stainless or Gold Brass piston pressure kit.

The height of the AirBuster® is NOT bigger then the height of our original piston pressure kit installed on your machine.

From my dear friend John M. H., we have this great info about Trapped Air & Spongy Pulls we make on La Pavoni Lever machines:

When the piston is in the down position, it prevents water from exiting the group head.
To brew espresso, the portafilter is removed, filled with finely ground roasted coffee beans and re-attached to the group head.
The operator begins the brewing process by raising the piston. This movement has multiple effects.
One, is that the upward movement forces some water above the piston back into the hotter boiler.
Another effect is that rising piston creates a vacuum underneath it which is readily filled with air drawn through the dry porous coffee grounds.
Finally, when the piston reaches the top, a hole is exposed on the side of the cylinder, allowing water to enter the area below the piston.​
​Ideally what would happen next is that all the air under the piston is driven back through the dry coffee grounds, and the area under the piston is filled with just enough water at the perfect temperature for brewing espresso.
Then, the forceful lowering of the piston drives that water through the ground coffee to extract a perfect espresso.
However, many users of direct lever machines will occasionally experience what is called a “spongy pull”.
That is, as they force the piston down with a lever, they notice the lever springs back up if they let go. This is due to some (compressible) air trapped in the area below the piston.
This is not an ideal situation because not enough water will be available for pulling the shot.
Also, when the portafilter is removed, any remaining compressed air may make a mess of things.
It is important to understand that it is steam, not liquid water, that effectively drives out the air underneath the piston.
When the water enters this area, it undergoes a rapid depressurization.
That is, the pressure of the water in the boiler is higher than the pressure of the air under the piston.
The rapid depressurization results in a small percentage of that water turning to steam, known as “flash steam”. While the percentage of water that turns to steam is small, the volume that steam occupies is large.
To better understand this, we can calculate the volume occupied by water that turns to steam, and the volume occupied by the water that remains liquid.
We can then compare these two volumes as a ratio.
By examining chart, we can see that at 105C, the water entering the area under the group head occupies about 15 parts of steam to 1 part liquid water.
In other words. at 105C, enough steam is generated to fill the area under the group head 15 times over.
At 100C or below, none of the water entering the area under the piston turns to steam.
This then is the reason why introducing cooler water into the area under the piston results in spongy pulls.
The remedy of course is to increase the water temperature by, for example, maintaining a higher group head temperature.
However, brewing espresso benefits from water at a temperature in the range of 91-96C to keep it from over-extracting the coffee, which yields a bitter taste.
This intricate knife-edged trade-off of these types of lever machines makes them endearing to many.
With this understanding then, it should be easier to understand the thinking behind the “air buster”.

Kit content:

1. AirBuster® release valve (brass);
2. AirBuster® chamber for release valve, including the water collector + water cap + gasket for the inside of the cap;
All are made from polished Stainless Steel.
3. One Teflon washer;
4. Teflon tape for sealing purposes;
5. One Left (L) or Right (R) pressure gauge;
6. T shaped connector for shaft + gauge + release valve triple connection;
7. Pipette used for removing the water from inside the collector chamber;
8. Small tube from silicone;
9. M6 acorn nut.
If removed, lets the user install the provided silicone tube for water flush purposes.