Fifteen bar on the Ulka E5 curve is zero flow

The number fifteen bar shows up in domestic espresso writing as if it named one thing. In the documents examined for this article it names at least three different kinds of claim: a point on a vibratory-pump flow curve, a machine technical-specification line labelled pump pressure, and marketing language that treats a 15-bar pump as the thing delivering extraction. Those classes are not interchangeable. Reading them side by side is the contribution. This is not another general argument that “fifteen bar does not matter,” and it does not re-litigate pump versus gauge versus puck pressure already treated elsewhere on this site.

What the component datasheet actually prints

CEME Group hosts a three-page Ulka technical sheet titled Family pump E - high pressure (Scheda tecnica E high pressure). Page 1 gives materials, dimensions, duty-cycle pointers, and storage notes. It does not print a headline “brew pressure” figure.

Page 2 is a table of Average Flow Rate [cc/min] against Pressure [bar] for models E4, E5, E7 and E4R, with the same data plotted as curves. For the common E5 column the table examined here reads:

At fifteen bar the E5 average flow is zero. On that sheet, fifteen bar is the pressure at which the tabulated E5 curve has already reached shut-off under the manufacturer’s average-flow test conditions with water. It is not labelled as a brewing setpoint, a gauge reading during extraction, or a pressure at the coffee bed.

Neighbouring columns make the same point for other models: E7 reaches 0 cc/min at 7 bar; E4R at 10 bar; E4 still shows 100 cc/min at 15 bar and 0 at 19 bar. Fifteen bar is therefore model-specific curve behaviour on this sheet, not a universal espresso constant the manufacturer is publishing for coffee.

The sheet states that the pumps are designed and tested using water as the fluid. It does not state where in a finished espresso machine the tabulated pressure would be measured, and it does not mention over-pressure valves, brew gauges, or baskets.

What machine documents do with the same number

Machine documents examined here reuse fifteen bar as a pump pressure specification line.

Gaggia’s Besana manual (RI8180 / HD8651; English technical-specifications page in the Rev. 01 PDF examined here) lists the feature/value pair Pump pressure / 15 bar as a machine technical specification, alongside tank capacity, boiler material and similar hardware lines. The English page examined here does not define the measurement point, does not say the figure is a brew-gauge target, and does not mention Ulka or CEME.

De’Longhi’s Classic Signature EM450M product page does the same in its technical table:

Pump pressure (bar) — 15

So far that is still a pump-pressure kind of claim: a machine-level restatement of a high figure associated with the pump, not a demonstrated puck-inlet measurement.

The same De’Longhi page already splits 15 from 9

The EM450M page is useful because it does not stop at the table. Under “Optimal extraction” it states that a “15-bar Italian professional pump” delivers “a consistent 9-bar extraction” (with auto-stop). Bullet copy on the same page also calls that 15-bar pump the source of “the perfect pressure” for listed drinks.

Read strictly, the manufacturer is already using two numbers on one product page: fifteen for the pump figure, nine for the extraction figure it pairs with that pump. The page does not show how those two are related hydraulically, does not cite a pump datasheet, and does not identify a sensor location for either figure. What it does establish is that, in this manufacturer’s own marketing, “15-bar pump” and “9-bar extraction” are allowed to coexist as different kinds of claim attached to one machine.

That is the opposite of treating fifteen bar as the brew figure. It is also not a measurement of what reaches the coffee. It is manufacturer copy that already refuses to collapse the two numbers — while still advertising fifteen.

What can and cannot be concluded from these documents

Established here. On CEME/Ulka’s Family E high-pressure sheet examined here, fifteen bar is the tabulated pressure at which model E5’s average flow is 0 cc/min. On the Gaggia Besana manual examined here and De’Longhi EM450M page, fifteen bar appears as pump-pressure machine language. On the same De’Longhi page, that 15-bar pump language is paired with a claimed 9-bar extraction. Those are three documented uses of one number, and they are not the same claim.

Not established here. That every domestic “15 bar” advertisement descends from this Ulka sheet; that a machine listing “Pump pressure 15 bar” is therefore running fifteen bar at the puck; that De’Longhi’s “9-bar extraction” sentence is a verified gauge or puck measurement; or that fifteen bar is “wrong” as a component capability. A shut-off point on a pump curve is a real hydraulic rating for that model under the sheet’s test fluid and conditions. It is not, by itself, a brewing prescription.

Parts catalogues often collapse the E5 shut-off into a one-line “max pressure 15 bar” specification for replacement pumps. That renaming is consistent with the curve, and it is still a component rating, not evidence about bed pressure during a shot.

What was not checked

Only the CEME Family E high-pressure sheet examined here, Gaggia Besana Rev. 01 manual, and De’Longhi EM450M page are relied on for the three kinds of claim above. Other Ulka families (including higher-head EFM variants) and other machine brands were not checked here. No machine tear-down in this article identifies which exact Ulka model sits in the Besana or EM450M. The finding is the document reconciliation, not a parts inventory of those SKUs.

This site’s separate pressure article treats nine bar’s provenance and the pump/gauge/puck distinction. This article does not repeat that mechanism account; it only needs the narrower point that a component shut-off figure and a brew figure are different kinds of claim even when a manufacturer prints both.