Product Review: FCI FLT93B Flow Switch

Before we get into our review of the FCI FLT93B, you might want to peep some of our other reviews of level switches here. They’re pretty good, but we realized that we lacked reviews on flow switches. We had some on thermal flow meters, and those can work as flow switches if necessary. But they provide more process information and generally cost more. What if you want to keep it simple and cheap?

Fluid Components International markets the FLT93B as a flow switch and temperature monitor, but the technical materials say you can deploy it as a level monitor too.

So let’s dive into the thermal switch universe and see how this doohickey works! Stick with me to the end of the review and answer our poll, too!

Disclaimer: This product review examines only features, not performance. If you’ve used this device, feel free to share your experience in the comments. This content serves the purpose of providing information if you want a new device.

Whatcha got there?

First off, let’s talk about the interface and design – simple housing, and no display or buttons for local setup. Switches don’t really need anything fancy that can affect the price, but it could’ve had a simple way to set it up, don’t you think?

image of FCI FLT93B Flow Switch
Courtesy of directindustry

Luckily, YouTube has plenty of easy-to-understand videos that show how to set it up, calibrate it, and more. And you’ll need them, because the manual falls short of user-friendliness.

In general, the FCI FLT93B can save money across a wide range of applications. It has many ways to install it, and if you need a different model, FCI offers the FLT93S, FLT93F, FLT93L, and FKT93C.

What can it do?

The website describes the device as a flow switch, but you can use it as a level and temperature switch too. So let’s sniff out the products the FLT93B can detect and monitor.

For water-based liquids, the range goes from 0.003 to 0.9 meters per second (mps), and hydrocarbon-based liquids get 0.003 to 1.5 mps. Air or gas has 0.08 smps at 21.1 degrees Celsius and 14.7 pounds per square inch absolute (psia).

image of FCI FLT93B
Courtesy of fluidcomponents

It has decent accuracy as well. In a liquid, you get +-0.5% or +-0.012 mps, in gas, +-0.5% or +-0.06 nmps, and in temperature, +- 1 degree Celsius.

For any type of level application, the response time is a critical point. You don’t want a delay if something happens! The FLT93B can give you a response time as low as three seconds – pretty good, actually.

Why should I care?

The FLT93B offers good cost benefits plus a few features that may benefit your process. You get a flow element made of welded 316L stainless steel and three insertion lengths – 30, 51, and 102 millimeters. And it can work from -40 to 177 degrees Celsius and up to 250 bar (g).

You can set the output signal up to relay contact on a dual single-pole double-throw (SPDT) or single double-pole double-throw (DPDT). Confused yet? You also have direct current voltage related to the flow and level and proportional to the temperature.

Last but not least, it comes with approvals such as FM, ATEX, IECEx, and INMETRO. And the website shows examples of applications, such as drain line flow, oil well system testing, and pump protection.


The FLT93B is a simple thermal switch that can monitor level, flow, and temperature in many scenarios. Of course, you have other options, and you can see several of those on the right. But even without a local user interface, the FLT93B can do many things. If you want to learn more about it, then watch this video and visit our device page.

Click the play button to learn more about the FLT93B thermal flow switch.


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