Our Feature Presentation: How a Pressure Gauge Is Made

Video shows the skilled labor that goes into building these precision instruments

"In a tribute to the documentary series "How It's Made", we present this video by our friends at WIKA "How Pressure Gauges Are Made".

- Swagelok Northern California 

We don't expect our customers to think much about the skilled labor that goes into making a pressure gauge. It's a sign of confidence in a product when you can simply take it out of the box, connect it, and move on to other tasks without a second thought.

Even so, it's worth taking five minutes to watch the video below from gauge manufacturer WIKA to see the intricate assembly process.

Making a face

It starts with a technician putting a blank aluminum faceplate into a printing press to create the scale.

While that's going on, another technician puts a copper tube into a machine that bends, partially flattens and cuts it. This piece of copper will become a Bourdon tube, the heart of the gauge. As pressure rises inside the tube, it flexes. This is what will make the indicator needle move when the whole mechanism is assembled.

Next comes a brass connector to link the Bourdon tube to an inlet pipe. The next time you pull a gauge out of the box, consider that someone hand-soldered the tube to the connector. The other end of the tube is hand-soldered to the internal mechanism of the gauge.

The whole assembly goes into a cleaning machine to get rid of any dirt and loose solder particles.

Each clean assembly then has to pass an individual pressure test to make sure there are no leaks.

An assembler then puts in a system of gears that will convey the movement of the metal tube to the needle on the front of the gauge.

Comfortable housing

The completed assembly goes into a protective stainless steel housing. At this point, it's starting to look a lot like the finished product, but there are still a few more steps. The assembly has to be calibrated to needle shows an accurate measurement. Only then can the faceplate and indicator needle be attached permanently.

A glass faceplate then goes on the front, held on by a crimped metal ring.

At this point there's still a hole in the 12 o'clock position of the housing. That's where glycerin is poured in. The clear liquid does double duty, lubricating the moving parts and damping vibrations during operation. (There are times, though, when you might prefer to use a dry gauge. We stock both kinds. Read more about the advantages of each.)

Now when you pull a pressure gauge out of the box, you'll have a better sense of what's inside. 

What's next: Get Swagelok literature on our measurement devices, then get in touch for local help with choosing the right components for your application:

(Prefer to talk live? Please give us a call at 510-933-6200.)

More on this topic:

• Stop Squinting at Your Pressure Gauges and Thermometers (blog article)
• FAQ: To Fill Or Not To Fill a Swagelok Pressure Gauge? (blog article)
• Swagelok Pressure Gauge Selection and Installation Tips (blog article)