Product Review: WTW IQ Sensor Net DIQ/S 181

I know you came to see what we had to say about the DIQ/S 181, but for the newbies, I want to pop in a quick recap of related subjects and reviewed devices. So far this month, we’ve talked about how to scale and calibrate a pH sensor. We also discussed devices from Endress+Hauser, KNICK, Mettler Toledo, and Yokogawa.

And here we have another company new to Visaya! The gang from WTW  brings the IQ Sensor Net DIQ/S 181, an entry-level device from the company portfolio. WTW has a long history and a strong showing in the field of analytical devices. Let’s find out if the DIQ/S 181 can fit in your application.

Grab a daquiri, take a seat, have a read, and draw your conclusions!

Disclaimer: This product review examines only features, not performance. If you’ve used this device, feel free to share your experience in the comments.

Whatcha got there?

The DIQ/S 181 makes a decent first impression with its simple yet familiar design. Where have I seen this before? Come to think of it, it looks a bit like a thermostat in your house, doesn’t it?

The DIQ/S 181 is small, at 144 x 144 x 95.2 millimeters, and surprisingly light, at 0.7 kilograms. I like the white backlight on the display better than the orange or green you’ll find on other devices, but that’s more preference than plus. It has a local keypad for configuration, where you can easily navigate to the device menu.

DIQ/S 181
Courtesy of WTW

Now let’s dive into the input possibilities. As a multi-parameter device, it can use different sensors in the transmitter inputs. It can measure pH/oxidation-reduction potential (ORP), conductivity, oxygen, or turbidity. You won’t find that last option on many other transmitters, so that counts as a plus. Unless you don’t need it, of course. Despite the multi- in its description, you can connect only one sensor to it, so make your choice carefully.

What can it do?

Because you can connect only one sensor, you can measure pH/ORP, oxygen, conductivity, or turbidity. Note the “or” instead of “and.”

So what about hazardous or harsh environments? Well, the DIQ/S 181 comes in an IP66 enclosure, which is pretty solid. But as far as approvals go – uh, I didn’t find any. Did I miss something? Can someone comment on this?

You can power up with 110/220 volts or even 24 volts. However, it doesn’t do loop power, so here comes another cable. And seamless integration is a low point here, nothing but analog. Pretty underwhelming.

Why should I care?

Keep in mind we’re reviewing a basic device here, so you may need to adjust your viewpoint. Fewer fancy features mean fewer things to go wrong, and it’ll probably fit your process and your budget neatly.

Although the DIQ/S 181 doesn’t have a digital protocol, it has two analog outputs and three relay outputs. You can do a lot of things with those. Sadly, the lack of digital protocol means you’ll have to set up the device and check its diagnostics in the field.

DIQ/S 181
Courtesy of WTW

As for user experience, the menu navigation is simple and clear, but the keypad could use a little tweaking. It has buttons with letters, but what do they mean? You’ll either have to check the manual before you press one or press one with your fingers crossed. And who reads the manual the first time? 🙂

Last but not least, no digital sensors here, just more analog. If you want a solution with both, you need to keep looking.


The DIQ/S 181 has the features you need to measure your process and some output possibilities, despite the lack of digital protocols. You could probably work around to some good solutions with it.

This is the best video I could find about WTW’s products:

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