bigNG users? DDC 18W impulse rate?

~~Snyxxx~~ · 05-27-2007, 01:36 PM

I have hooked up the bigNG and sensorbus and evrything seems fine except I am not sure about my flow rate. My DDC-2 18W's RPM cable is connected to the sensorbus flowmeter connection. I observed the following:

1 second sampling = 17.9 l/m = 9180 imp/m
2 second sampling = 2.9 l/m = 1470 imp/m
3 second sampling = 7.9 l/m = 4040 imp/m
4 second sampling = 2.9 l/m = 1470 imp/m

I know the rpm cable on the mobo shows the ~4000rpm is correct, but does this equal the impulse rate? I read somewhere that the DDC pump gives 2 impulses per RPM.

My gut feeling tells me that the 3 second sample rate is correct looking at the flow rates of all the pump tests that have been done. My loop is pretty restrictive.

Any help would be appreciated. I am thinking about flowing into a bucket to determine myself, but maybe y'all can save me some trouble.

Thanks.

Sideroxylon · 05-27-2007, 11:03 PM

Are you running in PWM or analogue mode? You should be running in analogue for your pump.

virtualrain · 05-28-2007, 12:33 AM

Quote:

Originally Posted by Snyxxx

Any help would be appreciated. I am thinking about flowing into a bucket to determine myself, but maybe y'all can save me some trouble.

Thanks.

I understand the pumps have a 2 pulse per RPM rate as well. The only way you can calibrate the signal to your flow rate is to do exactly as you suggest and measure it with buckets since every loop is different, no one here can possibly know your actual flow rate.

~~Snyxxx~~ · 05-28-2007, 08:16 AM

The pump is being powered by a normal molex connector and not the bigNG. I only had the rpm signal cable going connected.

Update-I did the flow test and it works out to be 6.5 l/m. Pretty close to the 7.8l/m that goes with the 4000 impulses/minute. Maybe I will calibrate it to match, but I would still like like to know what the impulse/liter for the pump is.

I guess the DDC has constant rpm and would not very with flow, right?

MnM · 05-28-2007, 08:49 AM

I got the exact same pump and bigNG so I am watching this with a lot of interest.

My system is still being built so I can not have any input yet.

~~Snyxxx~~ · 05-28-2007, 09:04 AM

I do have another DDC-2 laying around and I think I will perform the flow test with the pump only, to see if the flow rate is any different.

Stay tuned.

virtualrain · 05-28-2007, 10:11 AM

I don't think the pump has a "pulse per liter" spec. At a given voltage, it will rotate at a given RPM and produce a certain flow. The best you can do is at your operating voltage in the loop configured as it will be used, monitor the RPM and do a flow test by breaking the loop at some point and using a pair of buckets to determine at that voltage and RPM, what the flow rate is.

Then if you use the BIGng to control the voltage to the pump, it or you can extrapolate the flow rate from the known test point.

In the end, knowing the flow rate is almost useless. As long as your pump is spinning at or near the desired RPM, who cares what flow rate is?

pH(x) · 05-28-2007, 10:35 AM

I have a similar pump -- not currently in use though.

What exactly is a bigNG?

edit: nevermind, looks handy

http://www.specialtech.co.uk/spshop/...cat=566&page=1

~~Snyxxx~~ · 05-28-2007, 11:05 AM

@virtualrain:

Yes, I agree knowing the flow rate is pointless. At first I was going to dismiss the flow rate and use as either flow/no flow monitor only. But, my curiosity got to me when I changed the sample rate as above.

I knew what the theoretical flow rates were, but was curious with my storm and EK FC block what the flow would be. Mainly, was 7.9l/m or 2.9 l/m correct? To be honest, I did not know. You are correct that the bucket test is the only for sure way of knowing.

Thanks for the comments.

virtualrain · 05-28-2007, 04:17 PM

Quote:

Originally Posted by Snyxxx

@virtualrain:

Yes, I agree knowing the flow rate is pointless. At first I was going to dismiss the flow rate and use as either flow/no flow monitor only. But, my curiosity got to me when I changed the sample rate as above.

I knew what the theoretical flow rates were, but was curious with my storm and EK FC block what the flow would be. Mainly, was 7.9l/m or 2.9 l/m correct? To be honest, I did not know. You are correct that the bucket test is the only for sure way of knowing.

Thanks for the comments.

As you may have read in historical threads, I use to be a fan of flow meters, but over time, that has eroded... I just don't see a use for them anymore.

I do agree that it's helpful to understand what your actual flow rate in your loop is (you might be surprised how low it is), but the bucket test is the best way to do that.

Let us know what you find if you do the bucket test.