Accuracy of flow meters - pump power

[moogthedog]

I have a little spinny flow meter in line with the pump output in my loop. Sometimes it flies around, and sometimes it's a lot more sedate.

The pump is powered straight from a 4-way Molex on the PSU, has no speed control, and shares the connection only with the two fans attached to the rad. As far as I can tell, there's no change in the pump speed during normal operation of the PC. I've also tried connecting it directly to an external supply as a sole device (with the PC off while I'm dicking about), and the flow meter still seems to be... irregular.

The meter is a sideways-on 6-fin affair.

Is it routine to see a variance in the speed of a flow meter?

 

[Bugbait]

Is it routine to see a variance in the speed of a flow meter?

No, the water flow should be constant if the pump is working properly. Gunk build up on flow spindle? Does your pump have a 3 pin connector with a single wire so you can monitor the pump RPM?

 

[moogthedog]

No - It's just a thing to look at so you can get a warm fuzzy feeling that something's actually happening. I'm pretty sure it is just the meter, rather than a problem with the pump.

Something to keep an eye on, then. I've got a birthday coming up, so I may splurge some pennies on something I can monitor...