A few years ago, a motorcycle design and manufacture company approached us about a 5000 psi digital pressure gauge. They wanted to measure pounds of force from a ram with a diameter of 5 inches.
Our digital pressure gauges can be set up using the "Custom Units of Measure" function to read in pounds. To do this, you need to figure out the multiplier for converting psi to pounds based on area where the force is applied. The manufacturer of the ram or the hydraulics sometimes provides this. When it doesn't, you'll need to do a few calculations to figure it out.
Calculate the area of the ram used in the application:
In order to get the psi to lbs multiplier for our motorcycle manufacturing friends, we need to calculate the area of the 5 inch diameter ram. The formula for this is: Area = pi X the radius2 (A=πR2). So we multiply π (3.14) by 6.25 inches (radius of 2.5 inches2) to get 19.625 square inches.
To set the gauge to display in pounds, use the area in square inches as your multiplier, and skip to the programming steps below. However, you might have noticed that the full-scale equivalent of 5000 psi is 98,125 lbs. A 5000 psi gauge defaults to a four-digit display, and 98,125 is a hard number to show on a four-digit display. So if you (or, in this instance, our motorcycle manufacturing friends) want to scale that reading to tons, we'll need to do a smidge more math.
Formula used to calculate tons:
Next, we convert the full-scale psi (pounds of force per square inch) to full-scale pounds. 19.625 square inches at 5000 psi (19.625 X 5000) equals 98,125 lbs. Divide this by 2000 lbs, or one ton, and you get 49 tons. So, when our ram is pressing down to full-scale measurement on our 5000 psi gauge, we want it to display 49 tons.
To calculate the multiplier:
To get the multiplier that you'll enter into the gauge, divide the tons (49) by the psi full scale (5000). This equals 0.0098. Enter that into the custom multiplier screen on the digital pressure gauge.
Here are steps to program the multiplier into the gauge:
Step 1: Press the On/Off button once to enter the main setup menu.
Step 2: Press the Zero button to cycle through the options until UNITS is displayed.
Step 3: Press the Select button to access the Units setting options.
Step 4: Press Zero to cycle through the Units options until CUSTOM is displayed.
Step 5: Press Select to access the Custom Units setting. A 5-digit conversion factor will appear with the first digit flashing.
Step 6: Press the Zero button to change the value of the flashing digit (options: 0-9).
Step 7: Press the Select button to accept the flashing digit and advance to the next digit. Repeat steps 6 and 7 as necessary.
Step 8 After the last digit is accepted by pressing Select, use the Zero button to scroll through the custom units of measure; LBF, KN, LBS, KG, and NEWTON.
Step 9: Press Select to accept the desired custom unit and return to the main setup menu.
Step 10: Press Zero to scroll until you see EXIT, and press Select to return to the main display.
As always, let our Measurement Experts know if you have any questions about how to calculate your custom multiplier. Once you know the multiplier, our digital pressure gauges make converting PSI to LBS easy!