The C&D Blue Box in combination with our CDDAMS software gives you some pretty cool features that you probably never thought about or thought were impossible….Save time while flow testing with Virtual Orifices….. Work Smarter, Not Harder….
Flow testing from .050” valve lift up to max lift using an orifice larger than would be normally appropriate for low valve lifts is easily possible with the C&D Blue Box……
Using calibration orifices that flow less than your maximum flow range allows you to accurately calibrate a high flow orifice and use it for low flow conditions. This is accomplished quickly and easily through on the CDDAMS Orifice Flow Calibration Form.
You can calibrate a large flow orifice at various pressures and save it as a new virtual orifice. You save it just like any other orifice. The only difference is that you calibrated it at more than one pressure and save it with the appropriate coefficient of discharge & name it accordingly….
By doing that, you can leave your bench’s manual flow range adjuster set to your largest orifice and simply select the virtual orifice you wish to test with from your saved orifices list.
As with any orifice selection change in CDDAMS, you simply click & go! There’s never any need to stop the box to reconfigure orifice data. Grab the one you need from your list and select it….changes are instant!
CDDAMS Orifice Flow Calibration Form
For answers to questions regarding features posted on this page, use the Contact Us form.
The Virtual Orifice concept works as follows….. [Coefficient of Discharge will be referred to as “Cd”]
In order to keep things simple, we won’t get into the variables of temperature and barometric pressure for now. We’ll assume a temperature of 70 degrees and 29.92 Hg.
The key to calibrating any orifice type flow bench is in understanding the coefficient of discharge of orifices. The coefficient of discharge value can change when the depression across the orifice is being calibrated at different pressures.
Example - You have a 4 inch orifice and you have calibrated it at the common rating of 28 inches of test pressure and your maximum measurable depression across the orifice [for CFM Calculations] is 15.2 inches of pressure. thus you have arrived at a coefficient of discharge value for the orifice. We’ll use .585 as the example Cd.
The calibrated peak flow through that 4 inch orifice is significantly higher than what would be accurately measurable using traditional analog manometers for a low flow condition. A low flow condition would be with the valve open to .050 or .100 inch checking lift.
Remember, with an analog manometer you need to keep the gauge above the 60% mark on the scale to measure the depression accurately. That forces you to keep changing flow ranges and it’s not very handy when you have flow tests to get finished. However, with an electronic sensor, you can overcome that obstacle. If things are done correctly [box & software design] the sensor is capable of measuring very small increments that an analog manometer can’t easily show you do to practical size limitations of the gauge itself.
Also, the as calibrated state of the 4” orifice won’t be accurate for the low flow condition either. What you can do is to add the orifice diameter again as a new orifice and calibrate it at a lower depression using a calibration plate that is appropriate for the CFM range you would normally use for a low flow condition.
You’ll end up with a different Cd value. So you simply save the orifice as a new orifice with an appropriate name to represent it’s new flow value and with the new Cd. Then when you flow test, you can leave the 4 inch orifice in place and select the appropriate virtual orifice for the CFM range you need during the low flow portions of the flow test [low valve lifts]. As you progress out of the low flow range, simply select the appropriate orifice on the main form for the CFM range you need rather than switching ranges on the flow bench itself.
You can configure as many virtual orifices as you have the need for.
Virtual Orifices allow you to work smarter
C&D Technologies 2016.
From C&D Technologies
New 4 Port CD-100-20 Box
Digital Manometer & Flow Bench Software
Latest Version of CDDAMS Software 1.07D Now Available