Learn how to calculate flow rate on your E61 group machine, as well as how to adjust flow rate, what flow rate to use and what the best flow profiles are.
Flow control is a tool to help you get more out of your coffee by extracting specific flavors, aromas, and nuances out of your favorite coffee. It allows you to use the flow rate of water to adjust the flavor and aromas of your coffee. If you have a very fresh coffee, you can use flow control to allow the CO2 to off-gas and control the brightness of your coffee. If you have an old coffee, you might want to start off with a high flow in the beginning and gradually reduce the flow to improve mouthfeel, and prevent extracting stale and oxidized compounds.
You can also use flow profiling and adjust the flow rate to cater to a particular roast level. For example, you can do a gentle pre-infusion for a light roast coffee and a more aggressive pre-infusion for a dark roast. Another impressive feature is the ability to replicate extraction characteristics of manual lever and pressure profiling machines, and if you like the occasional filter coffee, you can grind coarse and use a low flow to turn your machine into a single-serve filter coffeemaker. Flow control opens up a new world of possibilities and can brew your favorite coffee exactly how you like it with the right variables.
Adjusting Flow Rate
Now that you have a better understanding of flow control, let’s talk about flow rate and how we can adjust it during extraction to find the sweet spot. If you’re using an E61 flow control device, here’s how you can determine the flow rate.
- Measure the output over 20 seconds with the flow control set in six different positions.
- Measure at one-eighth of a turn open, one-quarter, one-half, three-quarters, one full turn and then one and a quarter turns.
- For this measurement, we used a scale for accuracy and it’s simpler to use for calculations, but if you don’t have a scale you can measure the liquid volume of the coffee.
- From there, let the brew water run for 20 seconds in each position and then divide your total weight in grams by 20.
Quick References for Adjusting Flow on E61 Machines
For anyone who needs a quick look at flow rate compared to the number of turns of the flow control device / valve, here's a few graphs for both vibration pump and rotary pump machines.
The increase in flow rate is gradual from fully closed to fully open on vibration pump machines.
For rotary pump machines, the range of flow rates is much wider, with a steep increase in flow when the valve is fully open.
What Flow Rate Should You Use?
The results from our measurements ranged from 1.5 grams per second at an eighth of a turn up to about 11 grams per second at one and a quarter turns open. By calculating these measurements and following this formula, you’ll know how far to open your flow control knob to get your desired flow rate.
If you’re using an E61 group machine and following the example described above, we calculated 60 seconds at a quarter turn and then five seconds at just under half a turn. We then reduced the flow to finished the extraction a little over a quarter of a turn.
This profile works wonders with super fresh coffee because the gentle start allows the CO2 to off-gas and decrease the bitterness compared to what you’d get with a full rate extraction of a really fresh coffee. By keeping the flow gentle and finishing off where it started, this helps to extract the sugars and flavors of the coffee and really build a sweeter aftertaste.
What are the Best Flow Profiles?
The process described above is just one example of how you can use flow control to improve extraction, and how to calculate the measurements to achieve your desired flow rate. There’s a lot more to the conversation on flow control and flow profiling.
Below are different flow profiles we've tried and tested that offer best results for different circumstances. For example, we have a profile for brewing a coffee shot, for fresh light roast coffee, for not-so fresh dark roast blends, for emulating lever machines, and one more for adding a sweet bump in flavor.
For drip style coffee, you want a low flow, by opening the valve by a 1/4 turn, and keeping it steady for about 40 seconds.
When using a fresh and/or light roast coffee, start with a low flow until 15 seconds, then open up the valve a bit until about 38 seconds.
For not so fresh beans, dark roasts, and bean blends, you want to hit it hard to start. Open the valve 1 and 1/4 turns until 15 seconds, then gradually close the valve until 40 seconds.
To emulate a coffee like you would make with a lever machine, start by opening the valve by 1 turn. At about 3 seconds, close the valve for another 3 seconds. Then open by 1 and 1/2 turns for about 2 seconds, and gradually close until fully closed at 40 seconds.
To give you coffee some additional sweetness, start with the valve 1/2 turn open until 15 seconds. Bump flow rate to 1 turn open for about 6 seconds, then return to 1/2 turn open until about 36 seconds in.