# Fluidyne manifold for 1/2 in copper U-tube legs

> What joins the two legs of a fluidyne liquid-piston Stirling engine?

- Category: Stirling engines › Thermoacoustic & fluidyne
- Kind: Hardware
- Basis: West's fluidyne; sockets at 1/2 in copper tube OD Ø15.88 (fit: socket); port at the 4 mm OD tube
- Page: https://xemstudio.com/objects/fluidyne-manifold-half-inch/ · JSON: https://xemstudio.com/api/geometry?object=fluidyne-manifold-half-inch · Plain text: https://xemstudio.com/objects/fluidyne-manifold-half-inch/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); linked files under their publishers' licenses

**Exact dimensions.** Every file is drawn at true size with no printing tolerance. The holes and pins that meet another part are listed below under Mating features, with the fit each joint needs; open those by your printer's or process's clearance before making the part.

## Notes

- The top of the fluidyne's displacer U-tube: a 90 × 24 × 24 block with 4 mm vertical-edge radii.
- An 8 × 8 gas passage 60 long joins the gas spaces above them.
- A Ø4 port from the passage out through one side takes the 4 mm tuning line (fit: press), which sets the phase.

## Mating features (exact size; open press / slide / run / socket by your process clearance, leave designed and clamp as drawn)

| feature | exact | mates with | fit | files |
|---|---|---|---|---|
| leg sockets | Ø15.88 | 1/2 in copper tube OD | socket | all |
| tuning / side port | Ø4 | 4 mm OD tube | press | all |

## Sizes

| parameter | value |
|---|---|
| block | 90 × 24 × 24 |
| sockets | 2 × Ø15.88 × 16, 60 apart |
| gas passage | 8 × 8 × 60 |
| tuning port | Ø4 |

## Where the files are

- Wikipedia: [Fluidyne engine](https://en.wikipedia.org/wiki/Fluidyne) — web — CC BY-SA 4.0 (text)
- C. D. West: [Liquid Piston Stirling Engines (1983)](https://www.osti.gov/search/semantic:fluidyne) — book, reports (OSTI) — reference / US Gov reports public domain (verify at link)
- Long Earth Society: [Engine builds](https://longearthsociety.com/engineering/) — web, video — LES site

## Free STEP/STL (1 parts, CC BY 4.0, Xem Studio)

Index: https://xemstudio.com/files/hardware/fluidyne-manifold-half-inch/index.json

- fluidyne-manifold-2x-1-2in-copper: [STEP](https://xemstudio.com/files/hardware/fluidyne-manifold/fluidyne-manifold-2x-1-2in-copper.step) · [STL](https://xemstudio.com/files/hardware/fluidyne-manifold/fluidyne-manifold-2x-1-2in-copper.stl) — fluidyne displacer manifold: two Ø15.88 sockets 60 mm apart joined by a gas passage, Ø4 tuning port for 4 mm OD tube

## How it fits

### Goes in or on
- [Copper pipe (ASTM B88 Type L and M), 1/4 to 2 inch](https://xemstudio.com/objects/copper-pipe-type-l-m/): 1/2 in legs in the Ø15.88 sockets

### Connects to
- [Silicone tube 1 × 3 to 10 × 14 mm (ID × OD)](https://xemstudio.com/objects/silicone-tube/): 4 mm tuning line in the Ø4 port
- [Fluidyne output-column tee, 1/2 in](https://xemstudio.com/objects/fluidyne-output-tee/): tuning line to the output column

### Alternatives
- [Borosilicate test tubes, 10×75 to 30×200 mm](https://xemstudio.com/objects/borosilicate-test-tubes/): glass leg

## Questions

**What tube size for a fluidyne?**

The manifold sockets are Ø15.88.

**What sets a fluidyne's frequency?**

The U-tube's natural period T = 2π√(L/2g): a 400 mm water column gives about 1.1 Hz.

## Fits with

- [Fluidyne output-column tee, 1/2 in](https://xemstudio.com/objects/fluidyne-output-tee/)
- [Copper pipe (ASTM B88 Type L and M), 1/4 to 2 inch](https://xemstudio.com/objects/copper-pipe-type-l-m/)
- [Silicone tube 1 × 3 to 10 × 14 mm (ID × OD)](https://xemstudio.com/objects/silicone-tube/)
- [Thermoacoustic heat exchangers, hot and cold, parallel plate, for 1.5, 2 and 3 in tri-clamp spools](https://xemstudio.com/objects/thermoacoustic-heat-exchanger/)
- [Stirling engine configurations: which type needs which parts on this shelf](https://xemstudio.com/objects/stirling-configurations-guide/)