3D printed metric to English adapter

Harpo · Jun 12, 2023

I could not find an adapter so I drew it up in fusion 360 and I will have it printed. Here is the back with the slot for the "O" ring

Harpo · Jun 12, 2023

Here is the other side. This is a 20mm to 1/2 English union for my RE flow meter.

cilyjr · Jun 13, 2023

Looks good, but I would be wary about using a 3D printed piece on any pressure side plumbing.

KStatefan · Jun 13, 2023

I also would be worried about using a 3D printed part in that application. I did print some plumbing adaptors for my tank but they were used in tank and had no risk if the layer adhesion was not good.

cilyjr · Jun 13, 2023

KStatefan said:
I also would be worried about using a 3D printed part in that application. I did print some plumbing adaptors for my tank but they were used in tank and had no risk if the layer adhesion was not good.

Me as well.
I especially would not use a 3d printed part on the pressure side. Meaning anything that is being pumped. I assume that's where this is going since it is using a measuring system to determine flow.

I could see anything from leakage to complete failure.

Harpo · Jun 13, 2023

Agreed. Very low flow and pressure

All_talk · Jun 15, 2023

What material would you have it printed in? It would need to be something that could be solvent welded correct?

Another option... The existing metric union coupling could likely be modified to fit the next larger size OD inch PVC pipe. A quick job for anyone with a manual lathe.

Or a Spears 8229- series adapter: https://blackhawksupply.com/pages/search-results-page?q=8229&page=1&rb_vendor=Spears

Or: https://www.marineandreef.com/Metric_Adapters_s/1204.htm

Or: https://www.bulkreefsupply.com/metr...=12431&indexName=brs_prod_m2_default_products

Or maybe this in part or whole: https://www.bulkreefsupply.com/metr...=12425&indexName=brs_prod_m2_default_products

Just some options that might let you sleep better at night.

Harpo · Jun 15, 2023

I just ordered the 20mm to 1/2 union. Hopefully the "O" ring is on the correct side for my application.

Harpo · Jun 15, 2023

I just thought of another option. Instead of schedule 40 PVC pipe I could use schedule 80 (thicker wall) and then turn down the OD from .84 to .78

Schedule 80 wall thickness is .159
Schedule 40 wall thickness is .109

I can safely turn down the schedule 80 to .787 (20mm)

All_talk · Jun 15, 2023

Harpo said:
I just thought of another option. Instead of schedule 40 PVC pipe I could use schedule 80 (thicker wall) and then turn down the OD from .81 to .78

That could be a option too. Is 0.78" the measured ID of the metric flange?

Harpo · Jun 15, 2023

.787 = 20mm

All_talk · Jun 15, 2023

I think opening up the flange or turning down the pipe are both options. Depending on the thickness of the flange on the union, the turned sch 80 pipe may leave more wall thickness on the modified part. That said, all of these fitting are rated for a lot more pressure than an aquarium system will need, the thinner wall should not be a problem. I think the only concern with modifying the parts is getting the fit right so the glue up correct.

KStatefan · Jun 15, 2023

I made fittings for my GHL flow sensors a couple ways. My first trial was using a chunk of pvc from McMasterCarr and machining the old and ID. The second way was gluing half a union piece to a section of pipe and turning the OD to size