Pro/Forums - View Single Post - Spot the difference

Cathar · 09-24-2006, 02:38 PM

5' (1.5m) of 7/16" (8mm) ID tubing presents around 60cm of pressure drop at 4LPM, compared to 3/8" which has 25cm of PD.

Given that 3/8" barbs really have a ~7mm ID, this creates a boundary transition PD of 9cm per 8mm->7mm ID interface, and 15cm per 3/8" -> 7mm ID interface.

i.e. In a 5' tubing lengthed system, with a pair of GPU blocks, a CPU block, a pump, and a small res, the total tubing and barb interface PD between 8mm and 3/8" ID tubing totally cancels each other out.

What this is saying is that if you're using an unmodified Laing DDC, and your "typical" w/c loop, then you may as well be running 8mm ID tubing rather than 3/8" ID tubing. Much of the 3/8" ID tubing with 1/2" OD has issues with turning corners easily due to the thin wall per orifice ratio, hence the sale of supportive kink resistave items. 8mm ID tubing would be more kink resistant.

i.e. it's not THAT much of a challenge. Use blocks and radiator which are both well into their performance plateau's by 4LPM* flow rates, and is there any need at all for a bigger pump and larger tubing?

(* On the assumption that said blocks and radiator don't total more than 1.5m of PD - barb interfaces excluded since I already factored that in - in order to facilitate 4LPM flow rates with a MCP350 pump).

This is all getting back to designing small, quiet and efficient systems that sacrifice very minimal performance levels to large pump / large tubing solutions, while being easy to route in small cases.

09-24-2006, 02:38 PM	#13
Cathar Thermophile Join Date: Sep 2002 Location: Melbourne, Australia Posts: 2,538	Re: Spot the difference - Maze 4 GPU 5' (1.5m) of 7/16" (8mm) ID tubing presents around 60cm of pressure drop at 4LPM, compared to 3/8" which has 25cm of PD. Given that 3/8" barbs really have a ~7mm ID, this creates a boundary transition PD of 9cm per 8mm->7mm ID interface, and 15cm per 3/8" -> 7mm ID interface. i.e. In a 5' tubing lengthed system, with a pair of GPU blocks, a CPU block, a pump, and a small res, the total tubing and barb interface PD between 8mm and 3/8" ID tubing totally cancels each other out. What this is saying is that if you're using an unmodified Laing DDC, and your "typical" w/c loop, then you may as well be running 8mm ID tubing rather than 3/8" ID tubing. Much of the 3/8" ID tubing with 1/2" OD has issues with turning corners easily due to the thin wall per orifice ratio, hence the sale of supportive kink resistave items. 8mm ID tubing would be more kink resistant. i.e. it's not THAT much of a challenge. Use blocks and radiator which are both well into their performance plateau's by 4LPM* flow rates, and is there any need at all for a bigger pump and larger tubing? (* On the assumption that said blocks and radiator don't total more than 1.5m of PD - barb interfaces excluded since I already factored that in - in order to facilitate 4LPM flow rates with a MCP350 pump). This is all getting back to designing small, quiet and efficient systems that sacrifice very minimal performance levels to large pump / large tubing solutions, while being easy to route in small cases.