Scollops71 wrote:The current Slayer owners manual suggests 60ml previously was 80ml per 30secs.

Oddly mine was shipped as 40ml ..

thanks for that. coincidentally, these are the 3 values i've been hearing tossed around! haha.

i would like somewhere in the realm of 1-1.5g/s but have heard reports of pump failure due to the low flow rate? is this possibly why they are amending the owner's manual?

it seems like yours was shipped at exactly where i'd want my pre-brew flow rate set at!

Could be Slayer Tech question....but the flow changes are linked also in chatter with bar pressure . Although not seen anything specific from Slayer or guides...i did ask, i got ..... crickets.

"linked also in chatter" as in a noise at full brew pressure?

the flow rate during pre-brew i thought was completely different (and un-linked) to full brew as they use different water pathways to achieve this?

Sorry to clarify.......I read in the forums about altering pressure was also linked (not physical) to temp shifting, so 9 bar to 8 and reduction or increase of temp. Then the added complexity of either 50, 60ml per second flow rate for example.

My understanding of the Slayer brew path is that there are two: pre-brew and brew that are controlled with the paddle. Each brew path is pressurized from the pump set to 9 bar. This gives Slayer its innovative preinfusion in pre brew because pressure keeps rising in pre brew as opposed to old school "line pressure preinfusion." Line pressure can only increase pressure up to the inlet, usually 2-3 bar. Slayer pre-brew can go all the way up to the pumps pressure limit since the pump is at full pressure and the flow is restricted with a needle valve so that flow is around 2ml/s and then adjusted by the user. Theoretically you can do your whole shot in prebrew, it will just take some time to get there (usually around 45-60 seconds to peak pressure if grind is fine enough).

In brew mode, I believe it goes through a different needle valve set to a much higher flow (I'm guessing around 9-10 ml/s, someone correct me if I'm wrong). This is why it is possible that going from pre-brew to brew may not reach 9 bar. The puck is softened and that may not be enough flow to compress such that 9 bar is reached.

Also, concerning temperature. Depending on anticipated heat loss from boiler to group, it stands to reason that using flow rates outside of what the Slayer engineers anticipated could lead to the puck getting hotter (too fast) or warmer (too slow) water since the rate of heat loss could change with the flow changing. Jim Schulman shows this on his Bianca review where he recommends a 10 second warming flush on that machine when doing low flow preinfusion to temporarily overheat the group to help with heat loss from the low flow since E61 wasnt designed for low flow preinfusion. Same principal should apply here, albiet not as drastic given the saturated group.

That's close to accurate, Jayson.

There is a 2-way valve that closes the main brew hydraulic circuit when pre-brew is selected. This forces all the water through the needle valve. Pre-brew shots can reach full pressure just as quickly as any other machine can with similar grind, dose and headspace. With a stuffed basket and a fine grind with a 2ml/s pre-brew flow, you could hit full pressure in 15-20 seconds. Leaving the shot in pre-brew will give you a decaying pressure profile. The rate of decline is set by all the same variables that allow a DE1 to hold flow rate low while following a pressure profile, if that makes sense. Puck degradation leads to increased flow which decreases pressure if left in pre-brew.

The main brew path contains a 0.7mm gicleur, but the needle valve remains a parallel path as switching from pre-brew to brew simply opens the 2-way that closes off the path through the gicleur.

Temperatures will remain much more consistent with a saturated brew group than on a TS machine. The brew tanks maintain set point temperature with zero flow just as well as when pulling a shot and they are fed from a separate preheated tank, so temperature stability on a Slayer should really be quite good independent of the flow rate into the puck.

Cheers!

- Jake

Scollops71 wrote:The current Slayer owners manual suggests 60ml previously was 80ml per 30secs.

Oddly mine was shipped as 40ml ..

My Revision 5e manual says 40grams per 30 seconds as the factory setting. Listed on page page 16. Has there been an update to that? I was in the middle of moving during this thread. Good stuff here. Thanks all.

spressomon wrote:RE: Repeating LaMarzocco flow with Slayer. Can't be done as far as I know. Slayer was specifically designed to mimic lever type extractions so the machine has a relatively slow ramp up to brew pressure (which isn't always 9-BAR). Whereas LM, without pressure/flow profiling modifications, goes from 0 pressure to full 9-BAR pressure quickly/instantly. Very different type of extraction and flavor in the cup. Some of the best shots I've ever tasted came off of a LM Linea by a barista that knew what he was doing! Having said that I appreciate the increased versatility of the Slayer relative to a wide(r) range of bean roast levels/profiles...

Sorry for butting in, as I have no dog in this hunt as they say...but what happens if you just move the paddle on the Slayer all the way to the full brew position immediately, without stopping in the middle pre-brew position?

Does it not just immediately ramp pressure as fast as the 0.7mm gicleur will allow, which is what the LM you're describing would do?

Greg,

I believe Dan was referring to early Linea machines, which had no gicleur. Our GS/3 machines employ a 0.6mm gicleur (as do modern Lineas, GB5s and FB80s, etc...), so they would behave much like a Slayer that skipped pre-brew if we chose not to profile our shots.

In either case, neither of our machines, nor Slayers can emulate an early Linea with instant-on brew pressure, though if you looked at the coffee boiler pressure gauge, you'd think they could...

Cheers!

- Jake

gr2020 wrote:Sorry for butting in, as I have no dog in this hunt as they say...but what happens if you just move the paddle on the Slayer all the way to the full brew position immediately, without stopping in the middle pre-brew position?

Does it not just immediately ramp pressure as fast as the 0.7mm gicleur will allow, which is what the LM you're describing would do?

What Jake _G stated. I need to edit my post as a manual lever can achieve immediate 9-bar (or whatever pressure you want). Whereas the spring lever's immediate ramp up pressure is related to the spring rate which is typically a slower ramp up to full pressure. I believe this is what Slayer was designed to mimic.

So, no, at least as far as I know from my Slayer 1G experience, you don't get a fast (a couple seconds or quicker) ramp up to full brew pressure by going full brew immediately from zero pressure/flow.