When you have a question about process automation that needs a short answer, let us know with #WishIknew and @Visaya! We’ll reply with a #WishIknew post. It’ll give a quick explanation, then some related articles, videos, or reviews if you want to know more.
Wish I knew how to install a magnetic flow meter!
Great question, and I’m super-glad you asked! Most magmeter problems out there stem from installation issues. I’ve known many companies to install magmeters without the minimum requirements or instructions. When they complained about accuracy, the field techs would find out that someone installed the meters wrong or in applications that wouldn’t support them.
People, follow the directions if you want the meter to work the way it should. You have no one but yourselves to blame if you don’t.
You won’t find any mysteries here. You need a minimum inlet and outlet run, a filled pipe, and a product with the minimum conductivity needed for your type of magmeter. And that covers most magmeters out there.
You might say, really? That’s it? Well, what if I tell you even today you can find “bad” magmeters in processes trying to measure non-conductive products? Yup. Believe it.
Now that you have an idea of how little it takes, let’s fill in those basics with some details. Before I do, you should know that these conditions can vary by vendor and model, so double check before installing, okay?
- The market standard for minimum conductivity seems to hover around five micro-siemens per centimeter, although you can find devices above and below that standard.
- Magmeters like for you to install them vertically with the flow going up. That way, you always have the pipe full or empty.
- You can install them horizontally, just make sure you install the transmitter correctly. For high temperatures, you should install it upside down. Remember that.
- You’ll find different recommendations on inlet and outlet runs, but you often see at least five times the diameter before the flow meter and two times after.
The new offerings
Some vendors have put out flow meters that supposedly work without inlet and outlet runs. That sounds good, because then you can fit the magnetic flow meter almost anywhere in your plant! However, check the fine print on the datasheet, and you’ll often find a lower accuracy than usual.
Other vendors claim their magnetic flow meter measure flow in partially filled pipes. If someone out there has such a meter working on a partially filled pipe, then please share your thoughts about it in the comments below. We’d love to know more about it!
Have a look at this video for more info: