PTS Flowbench Forum

"Twitchy" readings can be calmed down via the averaging feature on each channel in Flowsoft configuration.

What orifice plate sizes do you have?

Bruce:

AT 28", we have 100, 200, 300. (I don't know off the top of my head what their 16" readings are... 71, 151 and...226?)

Whatever you sent to Jim Lathan.

M

When Jim and I discussed this build we decided you would only need that set of plates for the range you are needing to test, yes they are 75, 151 and 226 @16"

The 226@16" plate would be the one you put inside your flowbench and use the 200 and 100 @28" to calibrate the motors we spec'd will be able to handle this range. We went with the motors you got to keep your flowbench build costs down as well as not adding extra plates in. I verified this set of plates would work in this configuration on my own flowbench. I wasn't sure if you could use the 200@28" with the 226@16" plate internally.

If now you are requiring more flow then yes you will need a larger inside plate.

Bruce:

Will we need more motors? Sounds like we'll definitely need the larger plate, but it's not needed immediately IF the motors can't draw enough.

M

Okay, so we have been using our bench off and on for 5 months and in that time we have added 2 motors for a total of 6. In our initial calibration we had some difficulty in getting the CFM indicator to zero. I think I read somewhere in the forum at that time to not worry as this reading essentially resets the next time one starts the bench software. So, on with the testing we went.

Recently we noticed that the software does not appear to reset on start so we began to track it for a few test runs. Testing in the intake mode with a head on the bench and the valve in that head closed we would get a reading of around 39 cfm. What's more as we continued to do more runs that same night, the CFM would start about 1 CFM higher for each subsequent run, so after 6 or 7 subsequent runs the CFM count on startup at 28 in. would be say 45 CFM.

I have read the calibration instructions numerous times, we have checked for leaks numerous times, etc. etc. What are we missing?

Sounds to me like a leak.

With no pressure applied what are average byte count showing in "show raw values"?

Did you use this number in your offset?

Is your DM sitting flat on the bottom pads ie not mounted vertically. The DM should sit on it's feet if not mounted this way your readings will not zero

The DM is sitting on its feet.

I assume you mean by "with no pressure applied" at the end of a run after the motors are turned off then showing raw values?

I tried this approach, using those numbers, and never had any luck affecting the zeroing. I do not remember what the numbers were now...

My notes from months ago seem to I was getting numbers like 65 and 74?

Can you email me a screen shot of the raw values with no pressure? Sitting at rest?

Post a screen shot of the configuration page as well. If your averaging is set high and sample low it will take a long time for the ssytem to return to zero.

Last What plate is inside (CFM@16") the bench and what kind of flow are you getting out of the head tested? I/E are you trying to over drive the CFM Sensor?

Rick