Antminer S19 / S21 Dual 120 mm to 6-Inch Venturi Shroud — Wide Base

Description

Venturi shroud for the Antminer S19 and S21: a bell mouth instead of a square step

A venturi shroud for an ASIC miner exists because of what happens at a sharp lip. Where a flat plate meets a round hole, air coming off the fan cannot turn the corner cleanly — it separates at the edge and rolls into a standing bubble that sits in the opening and narrows it. This shroud replaces that step with a contoured bell the air column can follow into the throat, drawn around the dual 120 mm exhaust face of an Antminer S19 or standard S21 and finishing in a 6-inch collar.

It rides on the wide 260 mm base plate rather than the 250 mm standard, which is not incidental here. A bell needs plate to blend into: the wider the flange, the more radius the curve can carry before it runs out of room and has to be cut short.

What it fits

• Antminer S19, S19j Pro, S19 Pro, S19 XP — dual 120 mm exhaust panel
• Antminer S21 and T21 standard chassis — dual 120 mm exhaust panel
• Any dual 120 mm exhaust face on a 120.0 mm pitch and 105 mm screw square
• 6-inch flexible duct over the collar

The same bell on the narrower 250 mm plate is the standard-base venturi shroud, for racks where machines sit shoulder to shoulder. Want the plain conical transition instead? The plain wide-base 6-inch shroud is the same wide plate without it. If tonal fan whine rather than duct geometry is the real complaint, that is a job for the dual 120 mm expansion-chamber shroud silencer.

How it goes on

Lift the shroud over both exhaust fans so the eight flange slots land on the fan screw holes, then refit with M4 screws and a 9 mm or larger flat washer under each head — or reuse the miner’s large-head fan screws, which bridge the 6.40 × 5.00 mm slots on their own. Every screw has between 8.11 and 8.50 mm of driver clearance, so the job is done from the back of the rack. Push 6-inch flex duct over the collar until it passes the retention bead onto the band behind it, and support the duct at its first turn.

Why the bell shape is worth drawing

Bell-mouth entries are old, settled geometry — they are how wind tunnels and inlet ducts are shaped wherever air has to enter a bore without tearing off the lip. A corner forces the streamlines to turn faster than they can, so they leave the wall; a curve of increasing radius asks them to turn gradually, so they stay attached to it.

• Replaces the abrupt plate-to-plenum step with a continuously curved wall.
• Uses the 260 mm plate to carry a taller, larger-radius bell than a 250 mm flange has room for.
• Merges both fan columns inside the plenum before the round transition, not at the collar mouth.
• Keeps all eight fan screws driver-accessible with the machine still racked.
• Shares the 6-inch collar with every other part in the line, so the duct run does not change.

Specifications

Open source — the bell is yours too

The bell profile was drawn in-house by D-Central Technologies, and it is not a secret. The shroud designs go out under CC BY-SA 4.0 through the 3D models download center, free to download, modify, print and sell. This model’s card links the ZIP: STL, CC BY-SA 4.0 licence, installation and safety guide.

What you buy here is the finished object: PETG in black or orange, made to order in Montreal, Quebec, in a mount style you would otherwise have to schedule yourself. The D-Central fund page supports the drawing work behind the catalogue.

Works with

• Antminer S19 / S21 Venturi Shroud — Dual 120 mm to 6″
• Antminer S19 / S21 Dual 120 mm to 6-Inch Shroud — Wide Base
• 6-Inch Flex Duct Adapter — Rigid Socket to Flex Collar
• 6″ 90° Duct Elbow (Compact)
• Antminer S19 / S21 Dual 120 mm to 6″ Expansion-Chamber Shroud Silencer

See the whole D-Central shroud and ducting system.

Frequently asked questions