THE TRUTH ABOUT ESPRESSO: Understanding Espresso Flow

[@patrickcasper7487]

Aww yes, what you describe here is the outcome of fluid mechanics which so few videos explain. Liquid flow through a packed bed, which is typically modeled with the Ergun equation. You can set the flow, the pressure drop and the characteristics of the coffee bed, but if you fix two of the three then the third is fixed as well. Grind parameters and bed characteristics effectively change the void fraction, sphericity and particle diameter which are the inputs to the equation besides flow velocity and bed pressure drop. Really great video!

[@LanceHedrick]

Appreciate it, Patrick! Thanks so much

[@AndreGomes1987]

I'm not a barista, just someone who bought an espresso machine and decided to make good espressos and simple latte art. I was not able to come close to making shapes, not even getting the foam down at all until I found your channel. Now I can make hearts and I don't have many practice cups in. Your style of teaching is perfect for me and I'm so happy I found you. Thank you for all your work, the information is so valuable!

[@matthewjulius5401]

My sense is that we'll look back in 5 years to how we've thought about pressure the same way we look back at obsessing over shot times. Yes pressure (and shot times) are helpful indicators, but they're only a way of getting insight into the main variables we actually care about. In the case of pressure, an indicator for flow and resistance. For time, an indicator of dose:yield, temperature, and flow/pressure. Super helpful video! Thanks man!

[@Gk2003m]

Seems to me that folks are mostly obsessed with weight (18g in, 36g out), yet I’m finding shot time is the biggest determinant of flavor profile. Number of seconds from first drop to end of shot. Yes there are variances. If I pre-infuse, I get a richer looking crema… but it doesn’t last quite as long in the cup. Likewise with flow control, I can have a bit more or a bit less in the cup as desired. But with or without pre-infusion etc, if I count X number of seconds from first drop out to end of shot the flavor profile remains consistent. So if we want consistent results, the shot time is the first item to make non-variable.

[@olivierbinet6960]

What an amazing video… I never understood why everyone was crazy about setting OPV to 9 bars and where often on very geeky forums they would say that doesn’t matter, the grind size does. Now I understand: if the OPV kicks in at 9 bars or higher, well that means your flow will just not be right. So whether it hits 9 bars or not does not matter. THANK YOU. It was so good I’ll subscribe to your channel, it is my first subscription ever.

[@cheekster777]

Lance: Yo yo yo, *slow* your flow! 😁😂

[@LanceHedrick]

Hahaha!

[@adambc2925]

I shot straight to the comments after that 😭

[@djentlover]

Bars

[@djentlover]

(pun wasn't intended, realized after)

[@prika58]

Thanks man...nice workflow. There are differences in design of machines. OPV valve is a security mesure in commertial machines. They have a main water supply plugged directly to coffe boilers. Pumps are set to 9bars and OPV valve is set to 12-15 bar. If the pressure reach 12-15 bar,OPV will open and relase the pressure to the drain. Machines with vibration pumps and water tanks...the pump delivers 15bar. And OPV is set to 9bar. So it is constantly returning water to the tank. Hx machines also have restrictions in thermosyphon pipes to control the flow.. We had good and bad espresso 40 years ago and with all the new technology we still have good and bad espresso. Just enjoy and have fun. Thanks again for your point of wiew.

[@LanceHedrick]

You are correct. Yep.

[@JoeySchaefer64]

FINALLY "converted" to Subscriber! Thanks again for the badass explanations and entertaining content! Mostly thanks to you, I've gone from someone that didn't even know latte was milk plus espresso, to pouring my own art! I love the science behind it all and you're the guy for that.

[@philmeyers9647]

If only all of the teachers of the world presented with passion and knowledge like this.

[@LanceHedrick]

Thank you so much! Means a lot, friend.

[@andreionutnegulescu1]

Hey Vsauce, Lance here! As a person passionate about education and making anything captivating and easy to understand, I profoundly admire you. I use you as an example to students regarding how one should explain something clearly. You have a very rare talent! Congratulations!

[@daniel.lopresti]

...or are you??

[@christianshobbies9292]

Wow. I just posted a homebarista post about water debit and this is by far the most comprehensive and thorough explanation on the topic I've found

[@tobyr21]

Lance, I saw your video on turbot shots, and I found this new video to be ALSO very clear and easy to follow. Thanks! I have a Rancilio Silvia V6, which means that I cannot control either the water debit or the pressure limit, but it really helps to understand clearly that when I am adjusting (1) the grind and (2) the degree of tamping provided by y Distribution Tool and (3) the number of grams of coffee in the basket, that I am adjusting all these things to manage, not the pressure, but the water flow. - Toby (a subscriber)

[@LanceHedrick]

Hey! Thanks so much for the comment. I will say, im pretty sure there are easy to perform mods you can find online to change the pressure! I'd give home barista a perusal

[@wellspokenman81]

Great video - helped me understand flow much better. Thanks Lance

[@samroesch]

Lance, you’re a legend. Took me a long while to figure this stuff out, wish I’d had this video to watch!

[@LanceHedrick]

Thank you so much!

[@fjaviergl99]

after years of using a LMLM i just got a Lelit Bianca to play with... this video was exactly what i needed!... keep up the good work

[@arch-rival5477]

I absolutely appreciate this video! Your summary at the end is fantastic. Thank you Lance!

[@channinghatcher8580]

Great video, I finally understand the actual concept when using the flow control on my Profitec and why I was having problems. Thank you

[@alexandermashkin2395]

Exceptional topic, Lance! This is exactly what I ve been looking for. I will be happy if you admit, that 9 bar mashines require a coarser grind than 15 bar. So if I change my opv spring to 9 bar - I will gring beans coarser than before

[@babackd.6485]

This blew my mind. Awesome stuff 😎

[@victorbarroscoch]

Hey Lance, great video! This is some of the best content I've seen on demystifying how the flow/pressure relationship actually works on espresso machines.

[@LanceHedrick]

Thank you! That means a lot. Appreciate you taking the time to comment and helping others in the comment section!

[@victorbarroscoch]

@@LanceHedrick Glad if I can help. Hopefully I haven't confused anyone further 😅 The complexity increases rapidly in this subject, and some people in the coffee industry use engineering terms loosely, causing even more confusion.

[@LanceHedrick]

Exactly. I'm trying to over simplify these concepts and build up slowly. I want this information to no longer be gate kept, but out in the open and UNDERSTANDABLE, as you know is difficult. Thanks sincerely for the support, friend. Means a lot

[@scottintexas]

Thanks for introducing me to Decent Espresso! I cannot wait to get one.

[@davidcheung9979]

Wow, that was super good and informative! Thank you Lance!

[@axel.lessio]

Just applied some of this, had the best shot from a Barista Express yet, with slight but pleasant acidity, great sweetness, chocolate aftertaste that is lasting half an hour after the shot. You're a saviour! 😂

[@Joh146]

Very clear as always from You. Many thanks.

[@hodgesmt]

I enjoy the diversity of your videos, you are covering all the bases of coffee and every video is full of education, fun, and verbal excellence! Even when you cover a topic I may not be interested in I watch it anyway and learn something. Please keep up the great work.

[@LanceHedrick]

Thank you so much! The support means so much to me. I appreciate deeply your kind words!

[@markusgottner2549]

Great explanations. Thanks so much. There is one thing I am unsure if I can agree. Would be great to discuss this with the folks around here. I understood Lance as follows: Let's assume we measure different water debits under no pressure conditions and note the corresponding valve positions. Lance said when pressure builds and the pressure exceeds the set pressure of the OPV a part of the water will take the way over the by-pass via the OPV and the rest ends as espresso. The water debit measured under no pressure conditions stays the same, but being distributed between OPV and coffee puck. Example: Water debit measured under no flow conditions at specific valve position is 4 g/s and at 9 bar OPV setting, 3 g/s go via the OPV and 1 g/s goes through the coffee puck. I don't believe at 9 bar the water debit the pump can deliver will be the same as under no flow conditions, but will be lower. With increasing pressure, the flow rate (water debit) a pump can realize decreases. This typical behavior of a pump can be visualized with a pump curve correlating pressure and flow rate. I agree that with pressures exceeding the max resistance of the OPV, the OPV opens and some of the water flow takes the by-pass and some go via the coffee puck. I only do not agree that the water debit as measured under no flow conditions is the same as at elevated pressure. What is your opinion on that?

[@LanceHedrick]

Yes. Sure. If you have a super fine grind and set debit in a machine is 9ml/s, but only 2ml/s can make it through, I doubt sincerely 9ml/s will remain. I didn't see the need of diving into this when explaining a concept foreign to 99% of the populous. I ran this by a few engineers in home barista forums and got their thumbs up for a simplified explanation of these concepts. Cheers

[@RobertoFernandez-k2f]

That was a joy of explanation!

[@playwright4peace]

That's what I need -- a video on the Gaggia Classic Pro! Thank you!! Looking forward to it!

[@peterfraunhoffer7126]

Really great video of a complex theme! Thank you!

[@dailyhomebarista]

I was always struggling to dial-in espresso, and this video was so helpful to make me understand what is my machine is actually doing when we say it brews coffee with pressure haha. Thanks for this great video again Lance! It was super understandable and helpful! Hope you have a nice day, and cheers! Pete.

[@coocooforcoffee4248]

My man Lance always packing with great information

[@ahikernamedgq]

Hey, Lance - you're repetitive. But, I like it. Great, educational videos. Appreciate you sharing your knowledge. Thank you!

[@LanceHedrick]

Haha thank you! The support is massive!

[@annaheya2109]

Some of us need all the repetition to get the idea in lol

[@glennespresso6865]

A very confusing subject, thanks for making it easier to understand.

[@gobgobcachoo]

Killing it with the deepdives lately.

[@LanceHedrick]

Thank you! Appreciate that, my friend. The support is massive

[@SanMartan]

Very good video Lance.. When you start playing around with pressure profiling and flow control it opens your world up..if you can use this on your machine the whole 25/30 second shot gets blown out the window

[@xRiniX666x]

Look at your channel growing! Love every video

[@alexanderbourquin6040]

Thank you so much for this video. Im just getting into the home espresso world and this really helped me understand the basics.

[@LanceHedrick]

Fantastic! So happy you found it useful. Thanks for the support

[@dalgor73]

that video on the exact week I received my E61 flow profil device... Might be a god after all

[@EricMacam]

Awesome video! I finally decided to download the se profiler app. On the first go I decided to record the flow profile of my usual manual pull on my Flair Pro 2, which is essentially a slow decline in pressure after a preinfusion and ramp up to 8 bar. It was affirming to see I pretty much followed a constant flow rate after I reached the initial peak pressure. Excited to now use the app as a guide.

[@Mikey___]

Great video Lance, thank you - both the delivery of the content and the quality of the editing are awesome

[@LanceHedrick]

Thank you so much! I appreciate the support

[@pintsizer]

Fantastic Lance! Could there be a follow up video on how flow rates influence flavour clarity and body? From what I have experienced long slow flow rates increase clarity but sometimes at the expense of body?? I guess the question is how to manipulate flow to extract different flavours and varying degrees of body from the shot.

[@mteltser]

Great job explaining a previously complex process!

[@LanceHedrick]

Thank you so much! Appreciate it

[@joseluismalagagranda4785]

Thanks a lot, great explanation how to get the best result at any expresso machine. Is just a matter to adjust the finest grind to allow the machine give the highest amount of pressure .

[@mikerichards5610]

Very very informative. I really enjoyed it and I'll be back!

[@Cat-Dog-Mouse]

Gotta love Lancelot

[@johannes4518]

I'm not sure if I get this right: In a classic E61 machine with the OPV set to 9bar(without a needle valve), the water debit would remain constant (e.g. 6g/s) until the OPV shuts it off. This would mean: 1. With a hypothetical constant resistance of 8bar, the espresso flow would remain at the water would have a constant flow of 6g/s, so after 5s, there would be 30g of liquid. 2. If that is the case, then every shot with a machine with an OPV has a flow profile, since it regulates the flow based on the pressure with the OPV. So every shot has a certain flow profile that solely depends on the resistance.

[@LanceHedrick]

If you read the caption, I mention that the input flow (water debit) does, in fact, lessen as the OPV kicks in and pressure is hit. So, if you set debit at 6g/s, and pressure is hit quickly, it would lower the flow and any excess goes through the OPV. I didn't want to convolute the message in the video because I don't believe it to be of high consequence, so I put it in the caption. But also, yes. You can flow profile blindly on machines, yes. Just go coarser than the machine can handle for the duration of a shot at 9 bars lol

[@johannes4518]

@@LanceHedrick Thanks! I didn't notice the caption. This is really wrecking my head right now (especially since I can only make espresso about every other month and have just access to the theory).

[@robertandil5950]

I love how quirky you are and so full of knowledge! Thanks for sharing these secrets :)

[@alvarovalencia8196]

Lance, you are killing it man! Love the passion and knowledge that you bring in every video. From one of the first videos I saw early on, I knew this was a channel to help so many with their espresso skills. Quick favor man, the more recent videos lately have been a really deep dive into a PhD level of espresso. Do you have anything on tap for the undergrad espresso students in the class just trying to improve their day to day coffee/ shot making skills? Thank you Lance!!!

[@LanceHedrick]

Yes! Definitely. I will be bouncing back and forth. I'm trying to hit as many people as possible! And this video, to be honest, though it might seem difficult, is important to understand!

[@gregorio5543]

So from what I understand is that you input flow onto the coffee puck (ex. 4gps) and it doesnt necessarily mean that the espresso will hit 9 bars (depends on the grind size). If its too fine, the machine will have a higher bar pressure even if the valve isnt fully open

[@Kathleen58]

This w as so informative. Thank you so much for sharing this.

[@ridzuanzaini6838]

great great great great video lance

[@jimmcphail8741]

Lance, so with a coffee machine that doesn't have any flow control, eg. Breville/Sage Barista Express, should you use the grind size to set the max pressure (since the pressure will drop as the espresso flow naturally increases over time) and then tune finer/coarser for taste?

[@devonmoonie6860]

Grind size will ultimately effect the flow rate yes.

[@scottklandl488]

You can also modulate flow with your steam wand unless it’s a dual boiler set up

[@keesketsers5866]

Very informative, thanks! I have an e61 with flow control and pressure gauge on the group and was struggling to wrap my mind around using it in and effective way. This helps alot.

[@LanceHedrick]

Awesome! I'm glad you found it useful! Hopefully you'll be ripping some delightfully extracted shots soon!

[@wynparksook5286]

Great explanation! Somewhat advanced so it took some time to digest.

[@espressoarabic]

Wow! So I got a BIG question: I have been profiling on my flair for long time thinking if I do 2 bars infusion, then 9 bars, then go slowly to 7 , that is profiling, but I didn't think about perfect grind size, means when I go to 9 bars should the grind be coarse enough to reach 9 then come back down? Bc if it is finer then it should, it will STILL go to 9 bars and go let, bc I'm controlling the force of the lever, BUT it will have a lower espresso flow, right? So, What is the range of good espresso flow then? If I want to do the slayer shot on my flair, 2 bars then 9 then down to 6 or 5, what flow does it need to stay at in each phase? After the infusion ramping up to 9, then start calculating the flow? And maintain that flow down to 6? What would be the flow rate that is adequate? Also, is there a different way to calculate the flow intra shot without an acaia scale and Profiler app? Thanks for the eye opener!

[@dumkopf]

Short answer: Depends. Long answer: Depends on grind, desired yield, desired taste, grinder.

[@fridgenugget]

Absolutely awesome explanation. Great way to think about espresso. Too much focus on pressure without the fundamental understanding. Keep up the amazing videos!

[@rudevectors8018]

Another brilliant video 😊. Now, this might be sacrilegious, but if I distill everything down. Using the same coffee, grind, puck prep etc, the only real-time metric/device needed to reproduce a shot, is the app + Acaia? All other concepts, water debit, even pressure, are great but not essential. As long as you see the flow, you can adjust a dial, and get a similar shot? Pressures maybe be different per shot, but the flow is the same. Have I got that right? I ask, because I’m trying to budget for a new setup and there are so many choices.

[@colbybader2228]

Wow. Say that. Very very clear. Much clear

[@yannicke5678]

Brilliant video! I’ve been playing around with my Bianca, trying to replicate some of the Decent profiles, too. Thanks to your explanation, I don’t need to worry anymore about not having understood the concept. You really break it down very well 😊

[@SanMartan]

That's what I have man...I normally go long pre infusion ramp right up then finish around 6 bar.... Works awesome with light roasts

[@amit_hanoch]

Amazing video! Would love to hear about dialing in the shot with the profile, as we could see here you had (of what I guess was a standard 18-19 modern espresso dose) an 45~50 grams of extraction so that's 2.7 ratio in about 40 seconds, how should I know what to expect? is the dial in just the same as the "regular" shot I pull? time is a major factor to know if I should go finer or coarser and here it's unknown because I'm not sure what to aim for

[@akronyme]

Yet another perfect explaination, I really cannot thanks you enough to put all the concept together and make it so clear. I will be very interested in different flow profile vs grain roast. I've made some experimentation and I didn't have a clear explanation As for the levers machine lover (and I'm talkin about putting pressure with your arm, contrary to pressing a spring witch gave the pressure back), some more infos are needed as I feel I can completely go up to 20mg/s or more without problem. Can we see it from a espresso output perspective instead of water input (I imagine that's one of the main reason of a pressure gauge and a profiler)?

[@LanceHedrick]

Yes. I'll do pressure specific videos, no problem. But the ideas are relatively similar as regards pressure is created from flow of water plus resistance.

[@jackchen6578]

First of all, thank you Lance for a great video explaining the water input flow, awesome! I was thinking about posting a very similar question since I also use Flair lever machine. In this case, isn’t that the variable we can control is the force that we apply onto the piston vs. how fine the coffee are ground. I cannot control the water flow into the puck (or cannot monitor) but only monitor the pressure through SEP and output flow. Is this considered as pressure profiling?

[@LanceHedrick]

Correct. It is considered pressure profiling, but you are technically controlling the flow with the force. The force/pressure is ONLY built by how hard you're pushing the lever and how much resistance the puck has. So, it is still using flo, but you are going off pressyre

[@bozomedicus5035]

I only truly understood this after buying my own Decent. There are only 5 input variables, two controlled by the espresso machine - temperature and flow, two controlled by the grinder - dose and grind. One, beans, controlled by the barista. Pressure is dependent on the interaction between dose, grind and flow

[@paprikar]

Yep, a little sad that lance forgot to mention dose weight as a factor

[@scider2]

If machine A has a flow rate without resistance of 5g/s and machine B has 10g/s, both have the OPV set at 9 bars, then doing an espresso on each, would those be about the same or how would their profile differ?

[@adarshshah9763]

If your grind is fine enough that the 5g/s creates a pressure at 9 bars, then there will not be much difference (though it will take longer to reach peak pressure at the beginning of shot, so you'd have more pre infusion). If your shot is more coarse then there will be difference. Whether it's better or worse will depend on the coffee and whether you're over or under extracting

[@scider2]

@@adarshshah9763 The grind should be adjusted so the brew time for both would be about 25-30 seconds, dialed in for tasty espresso you could say. You are definately correct about the preinfusion! Why I am curious is because of the video where Fabrizio Sención Ramírez talks about flow rate: kzbin.info/www/bejne/pGSXqoaaZa9sfKs&lc=Ugw4z51Hr2vUli-snOZ4AaABAg.9P_GcRK1_9d9P_Ocdaet8M. Here it seems as flow rate make more difference than what I thought at least.

[@geekmusicmaker]

Hey Lance, so what’s the point of the bluetooth pressure sensor that goes with the espresso profiler app ? And you said that pressure was an input with lever machines, so in that case is it also un-necessary to use the pressure sensor/transmitter ? Thank you.

[@matt-g-recovers]

I love that technology is unlocking a new frontier of espresso.

[@mithunfan]

One of the best coffee videos i've seen on KZbin. Nicely done Lance! Will you be able to help us understand how we can execute some of these principles on the Flair? My big learning is that the high stock pressure that comes on the machines is not really a dealbreaker at all if one is willing to put in the time to calibrate the grind. Looking forward to the gaggia video since im thinking of buying one!

[@Thecaveandcognitionmusic]

SUBSCRIBED AND LIKED! BEST COFFEE CHANNEL ON KZbin 🙌🏻

[@zrouh]

amazing tutorial !

[@matthewhoffman6868]

I don’t know if you pay respond to questions about old videos. But if you do, I’m curious about how all this plays out with spring lever machines, such as my Londinium 1. Thanks.

[@nakatateoh2381]

the video is so genuine I genuinely liked the video when he asked to. I rarely likes video but this is just so much effort and thoughts to not be liked. :)

[@candannixon645]

If pressure is the output variable, what does that mean for machines like San remo you or rocket r nine one that advertise pressure profiling, is that just a different way of controlling the flow? Is it worth it compared to cheaper machines that have flow control

[@marc-andrelanglais9506]

Thanks Lance for this video. Really interesting to get informations on flow vs pressure. Still some machine are based on pressure profiling while others are based on flow profiling. Id be interested in hearing your thoughts on which design is best suited to manipulate taste…. How you use flow profiling to dial in coffee would be very interesting as well as it adds multipls variables we have control on.

[@LanceHedrick]

Technically, no machine is really pressure profiling. Pressure is ONLY created by the multiplication of resistance times flow (thanks, Ohm's law). So, even lever machines, you are controlling the speed of the flow. You are met with resistance, which creates pressure, but in reality, it is based on flow.

[@marc-andrelanglais9506]

@@LanceHedrick I get that point but still some machines, (GS3 for example) shot the pressure output and play with the reqiuired flow to meet it. My question is probably better if asked like this: “is keeping pressure constant during pre-infusion and infusion phases - while flow change to meet that pressure - is better on taste or keeping flow constant - to a certain pressure is?”

[@LanceHedrick]

I prefer manipulating flow, not pressure thresholds, for better tasting shots

[@ahmedelmorsy8429]

I enjoy you videos and I learned a lot of them. Thank you for that. What are these two coffee machines in the video? Any recommendations or reviews on them as I’m planning to get a machine soon.

[@kg-Whatthehelliseventhat]

Left Breville or sage about 800$ usd Right Decent I think but I'm not sure +2000$ usd It is a good idea to focus on getting the best grinder you can afford first, then focus on a machine. The better the grinder the more consistent the grinds will be. Better does not always equal expensive. Also use quality water... Trust me the water used makes a HUGE difference. I thought just filtered tap and I live in a country with great water but after I made brewing waters 1 for filter and 1 water for espresso the coffee I made popped like never before. Holy crap was I surprised. The fruitiness, the boldness the depth of coffee was soooo much better. Please let me know if this helps and if I may ever be of assistance. If I do not know something, we can find the answer together. I just want people to enjoy their coffee. Nothing else here. 😊😊

[@brianruggiero2254]

Another great video Lance. Thank you. So how would you replicate a slayer shot on the flair 58? Are you able to measure water debit on a manual machine or do you just measure espresso flow and call it close enough?

[@Andy-ux3ge]

To my understanding, a device like Flair does not have any water input mechanism (i.e. a pump). Water moving through the puck relies completely on applied force/pressure. Hence I would assume that it is unnecessary to know or even measure "water debit". Therefore, I would think it is only essential to record the pressure during the brew, as well as the output flow rate. These 2 extra parameters, along with the grind size of coffee and brew time, is all you would need to make adjustments to and achieve the ideal espresso you're aiming for. To answer your question, replicating a slayer shot would be replicating the pressure profile + output flow profile. Slayer would control its input water by adjusting needle valve while Flair would do the same by adjusting applied force respectively. Hope this helps.

[@hosegooseman5]

Great stuff. Thanks !!!

[@juancarlosiza233]

Buenos días mil gracias por todo lo que aportas. Perdón te hago una pregunta que app manejas en el celular de la breville.

[@kg-Whatthehelliseventhat]

Artisan??? Idk... maybe try. I'm sorry I just wanted to help. 😊

[@kg-Whatthehelliseventhat]

Maybe the acacia scale has an app to the phone. Try smart scales. Let me know if this helps. 😊

[@amourb7133]

Great video keep it up! How long should be the contact time ? And Weight of yield ? On the slayer shot using the same set up

[@kg-Whatthehelliseventhat]

Depends on ratio. Usually 1:2 Contact time approximately 25-35 seconds. Usually... I hope this helps please let me know if this works for you. 😊😊

[@kg-Whatthehelliseventhat]

However, he did say 1.4gps. Idk what amount of coffee was used.

[@LukaZovko]

Lance, could you point me to some literature about the physics of espresso? I am really interested in the subject and would like to know more, but there is so many sources that it's almost impossible to filter the good ones from bad ones. Thank you in advance, and keep the videos comming, I love them!

[@fahadara]

I believe before even trying to experiment the flow control…. We need to find out the perfect grind size… so at what pressure (and other parameter) we need to experiment that?

[@DimHim7473]

Just a question for all companies out there.Why you allow the machine to go to 11 or 12 or higher pressure and don't fix it to stop to 9 bars? Is that dificult? Will it cost you more to make a machine? Why we have to do your job? Why do I have to open the machine and play with OPV or dialing the espresso and play with the flow or the steam wand to drop the pressure to my espresso? Why you don't listen the comunity at all?

[@pjrage82]

I’m curious why the output flow isn’t affected much / really at all when you did your slayer shot? You theoretically lowered water debit / input flow, yet output flow seemed to stay the same?

[@huntonworld]

How does ovp/max pressure work on Rotary Pump Machines with adjustable flow?

[@victorbarroscoch]

Both the vibratory and rotary pumps used on espresso machines are hydrostatic (positive displacement) pumps*. Which means they move a specific volume of fluid per cycle of operation, a constant flow, that depends on the rate of the pump. The OPV is basically a calibrated spring valve that diverts extra flow when it hits over a certain pressure, effectively creating a presssure ceiling, usually of 9 bar. The way you can control the flow is either adjusting the rate of the pump, or with dynamic adjustment of a flow valve. The first can work on open loop**, the second requires a feedback controller (like a PID or pressure compensation***) to work precisely, which is not the case for the slayer mod on the BDB. *The ulka reciprocating solenoid pumps present in most espresso machines actually don't create constant pulsing flow in all cases (not fully positive displacement). According to the patent they don't use the entire stroke length of the piston, in order to be quieter during operation. Max flow will depend on the pressure differential acting on the pump. Because of this, it's a little trickier to get precise flow out of them, but still doable. **A closed loop might still be required to control the rate of the pump, but in theory a direct measurement of the flow isn't necessary for a rotary vane pump. ***I'm not sure if the Slayer group head uses a standard or pressure compensated needle valve.

[@LanceHedrick]

Thank you for this response! Appreciate it

[@DiegoGonzalez-tm5hl]

Hey Lance! I saw the gaggia hanging around on the back lol. I was wondering if controlling the water flow on that machine was as easy as you make it sound lol. I’ve seen people managing to do pre-infusion with the gaggia by opening the steam wand a little bit, but could you do a turbo shot by using that same technique? I have a gaggia and I’ve tried the pre-infusion trick but I end up with more channeling than when I don’t do it :/

[@LanceHedrick]

Funny you ask- a week from today I'll post a video on the GCP!

[@DiegoGonzalez-tm5hl]

@@LanceHedrick awesome!!! Can’t wait to watch it 😃😃

[@amaryusuf7519]

what i can conclude from your video is, for the espresso machine that doesn't have OPV function,i need to tune in my grind size in order to get a perfect espresso shot,cause finer/coarser grind can effect the outcome yield from your machine.

[@Kiaulen]

Cheers Lance! Happy Friday!

[@LanceHedrick]

Cheers, friend! And happy brewing!

[@GR-qz8fx]

I did some more reading on this topic, and the term "water debit" in particular, and discovered that the term is partly French (whether originating in France per se or a French-speaking country/person, I don't know). The technically correct way of writing it is "water débit" (pronounced something like DAY-bee if you're an English speaker), and the word débit simply translates to "rate of flow." The value of the term is that you save a few words, using one instead of three (you can say "water débit" instead of "water rate of flow," or "water flow rate"), though I think for clarity, one should use the French pronunciation, as the English language meaning of debit has nothing to do with flow rates; or alternatively abandon the French and say "water flow rate." Don't even think about "eau débit"...

[@danielrustico]

Cool video, thanks! Always learning something :-) I wonder how you end up having a slot to fit the scale in your Breville / Sage. Did you cut it? Or bought a grill specific for it? A problem I have with my high precision scale is it shakes while the machine is working and I have trouble measuring anything with it. Maybe the slot is the solution to it.

[@kg-Whatthehelliseventhat]

Hello, I had a similar problem. I used non slip grip sheets I got at Daiso. Japanese discount store but any dollar type store should have it. Just double up the sheets. I hope this helps. Please let me know if this works for you. Note you can cut the sheets to fit. They look like a mesh of rubber like sheets.

[@danielrustico]

@@kg-Whatthehelliseventhat thanks! Exactly what I did and it works :-)

[@kg-Whatthehelliseventhat]

@@danielrustico right on!!!!! I'm so happy for you. That's great. How has your machine been? Any issues or problems?

[@danielrustico]

@@kg-Whatthehelliseventhat the Barista Express works hard every day (5x/day more or less since home office) and never failed me. The grinder broke though, no replacement part available. So I went for a Comandante manual grinder. No regrets, except for when I need to grind for more than just me. But very happy with the setting!

[@kg-Whatthehelliseventhat]

@@danielrustico wow!?!? Really. That is great about the machine, not the grinder. What grinder did you have? I love the c40 but might go with the 1zpresso line. I don't know. I saw LH video on grinders under 300$. As much as I love coffee, I am content with decent products. Great does not always mean expensive. Where are you located? I'm in Japan. They have a amazing coffee culture here. I was a bit surprised.

[@iconindexsymbol]

What does this mean for espresso machines like the Solis Perfetta where you can’t control the water debit? You only change the grind until it peaks at 9 bars?

[@endlessocean1731]

I have a machine with 15 bar pump pressure, and it doesn’t have the opv valve and flow control. So at the end of every shot, it will rise up to 15 bar and even more if i the ground is too fine. How do i do the hack thing to make a better shot?

[@cedriclahz4833]

Im still confused at how pressure relates to shot times for a given yield. My issue is I've been playing around with 7 bar on the "pressure setting" or opv. So I doubt the normal ball park metrics of 20g coffee for 40g yield in 28 seconds works? my palate isn't super dialled in that I really know what I'm doing with dialling in at different pressures? Do you have any tips for making espresso at lower pump pressures?

[@andyingraham9813]

Can you share the weight of your shot at the point you raise and lower your flow so we can work on dialing in our grind size to match? Thanks!

[@sanjaysingh-oc5vb]

Can you just tell me what are new needs, requirements, and need-requirement pair you have identified from the current espresso machine?

[@jasonvespa7452]

Great vid!. Wonder if acaia lunar + smart espresso profiler + blue tooth controlled manual switch could give you a gravimetric machine?

[@Sammiecheeks16]

Hey so I got the profitec pro 600 and haves flow control is that the same thing your doin as to dialing mine in with how much water goes through

[@LanceHedrick]

Yes! I would recommend using the smart espresso profiler app with a bluetooth scale and tracking your flow. Will help you greatly in dialing in different styles of shots.

[@lyleallan5124]

Been binge watching your videos...great info!! Have you had a chance to use any of the aftermarket flow controls for E61 machines? If so, do they do the job? thanks....

[@MastaLBC]

Great Vid on an important Topic.

[@LanceHedrick]

Appreciate that a lot! Thanks

[@ludog014]

How do you flow profile on a lever machine? There's no easy way to measure flow directly (how do you know how hard to press and for how long to target a certain flow?)

[@tgallife]

Lever machines are pressure profiling. If you wanted to do a flow profile you would need to control the displacement, which is almost impossible to do by hand.

[@LanceHedrick]

You can't dictate flow profiling on the lever, But you can mess with grind size and application of pressure, which gets you to the same place.

[@johanneslaudi6184]

i have a flair with no presure gauge, so what i did is i look at the output of the espresso coming out. i look at the weight and second on my scale, and try to estimate how many g/s the output is.

[@victorbarroscoch]

I think the only manual espresso machines that can do flow natively are the screw operated ones, like the Aram, Rota and Rossa. Cranks per second translates to exact displacement of the piston, ignoring some dynamic stuff that can happen with air in the system.

[@LanceHedrick]

Correct

[@d00mch1ld]

How did you modify your Breville dual boiler? With the smart profiler?

[@ChristopherMichaelR]

In theory can I adjust my OPV and use the app as a good guide for brew pressure?

[@LesliesDemos]

I can't add a needle valve to my Bezzera. Instead, can I pulse the voltage to the vibe pump in order to reduce the water flow?

[@LanceHedrick]

Yes! If you use a dimmer mod, can definitely lower the voltage. I wouldn't recommend turning it off and on, but lowering it!

[@slvrbach]

What millimeter measuring strip do you have on your needle valve?