The recommendation of a standpipe (or stand pipe) is somewhat common. They are occasionally needed to move an ultrasonic sensor back far enough to compensate for the blanking distance, or to act as a waveguide. They are even used to hold the level sensor perpendicular to the target surface when the top of a tank is not flat.
So when we recommend a standpipe, many often wonder how to it should be constructed and installed. This can be a relativity quick and easy process with a few helpful hints from the experts.
Here are four steps to follow when installing your standpipe:
Choose a seamless PVC or steel pipe with the appropriate threaded NPT fitting to mount the ultrasonic sensor. You can use a reducer if you need to.
- Note: Use the largest diameter and shortest length possible. As a general rule, the diameter of the pipe should be 1/2 the length.
Cut the end of the standpipe at a 45° angle. Make sure it is free from burrs.
- Note: Cutting the standpipe end at 90° will cause a standing wave echo to develop at the end of the pipe that will be seen as a target by the sensor. If a 45° cut is not feasible, cut as close to it as possible.
Place the pipe as vertical as possible with an unobstructed path to the target. Any angle off perpendicular will cause a degradation sensor performance.
- Note: Make sure the transducer face is at least as far away from the highest liquid level as the minimum blanking distance.
- Mounting the pipe is the toughest part. You can use a compression fitting, brackets, or metal straps. Whatever you use, the standpipe must stay in place, and must not move up or down, or from the vertical position.
We hope these tips have been helpful. If you still have questions, reach out to us via our contact page, or give us a call at 888-525-7300.