The DCR-1006A is a controller for our Modbus ultrasonic sensors with backwards compatibility for our long-running DST ultrasonics. It also works with our MPX magnetostrictive float level transmitters that communicate in Modbus.
Its main purpose is to configure the sensors and display the readings. Additionally, it has 4 contact relays and a 4-20 mA output for interfacing with larger control systems.
A common need is to display the level reading in gallons, whereas the default reading is distance in feet. The DCR-1006A can be programmed to read volume (such as gallons) in a number of tank types. The controller will allow you to enter the tank dimensions needed to accurately calculate volume.
If you have a spherical tank, or one with hemispherical ends, a hemispherical bottom, or a conical bottom, refer to the user manual for instructions on how to enter the proper dimensions into the controller for accurate volumetric measurements. Once you enter the dimensions into the controller, gallons will be available as standard unit of measure.
For this example, we’ll use a standard flat-bottomed tank for our gallon calculations. This will require some linear calculations, and gallons will be a custom unit of measure. This means it will require a multiplier – gallons per inch (GPI).
If you know the GPI, skip ahead to the “Converting To Gallons” section. If you don’t, let’s cover this important calculation first.
Getting your GPI is simple. You need to divide the tank capacity in gallons by the tank height in inches.
So if you have a 2000-gallon tank, and your tank height is 80 inches, that’s 25 gallons per inch.
With your GPI, you’re now ready to jump into the controller setup. Remember the numbers we’ve covered in this section, because you’ll need to enter these vertical measurements into the DCR-1006A controller.
Note: If you do not know your tank capacity, refer to the end of this article for instruction on how to do this calculation.
There are several steps needed to program the controller to read in gallons. This is a custom unit of measure, which is why we need to use the GPI as a custom multiplier.
Because the default is feet, and we’re using gallons per inches as a multiplier, we need to tell the controller to measure inches first.
The display has 5 digits, and many tanks are quite large. Our 2000-gallon sample tank is fairly small in the world of tanks. So while we’re busy calling our custom unit of measure gallons, we’ll also move the decimal point so we’re reading in whole numbers only.
Remember the blanking distance from above? If you’re using an ultrasonic sensor (and you probably are), you need to tell the controller about it. Here’s how:
Now it’s time to tell the controller that we’re doing a linear calculation. While we’re at it, we’ll set the empty and full distance from the sensor face – because the sensor measures distance from its transducer face.
Now that we have our end points, it’s finally time to enter that GPI multiplier that you calculated at the top of this article.
Note: Now that the DCR-1006A controller is speaking in gallons, you’ll need to stick to that unit of measure when setting up 4-20mA set points or relay trip points. For example, if you want a pump to turn on to empty a tank when the tank is 75% full, then you’ll need to turn it on at 1,500 gallons.
Converting your DCR-1006A controller to gallons takes a few steps, but is an easy task once you understand them. If, however, you don’t know your tank capacity, then we need to do some simple math before we can get this done.
Don’t know your tank capacity? No problem! We just need to do a little math together, and we’ll be all set.
Let’s use our 80-inch tall tank as an example.
To calculate the capacity, or volume in gallons, we need to use the following formula:
Volume = π × radius2 × height × 0.00433
So we need to measure the radius. This tank has a diameter of 86 inches, and therefore, has a radius of 43 inches. So we’ll square 43 to get 1,849 inches2. We’ll then multiply that by 3.14, or π. That gives us an area of 5,805.86 inches2. To get to cubic inches, we’ll multiply that by the height of the tank, or 80 inches, to get 464,468.8 inches3.
Finally, we multiply that by the constant 0.00433, which converts cubic inches to gallons, and we get 2,011 gallons. It’s not exactly 2,000 gallons, but that’s typical.
Unit conversions in the controller will prevent you from doing this math over and over again. A little investment up front will get your instrumentation speaking the same language and avoid the headache of manual conversion.
Let us know if you have any questions about using the DCR-1006A or any of its compatible sensors. We’re more than happy to walk you through the process.
