What Exactly Does a Gauge Siphon Do?

What Exactly Does a Gauge Siphon Do?

March 16, 2021

Explaining exactly what a pressure gauge siphon does can be a difficult task, especially when explaining to the uninitiated. Basically, it can be summed up by saying it protects a pressure gauge from damage from steam or other hot pressure media.

This piece of equipment is also called a gauge siphon, or a pigtail siphon (more on that curly nickname later). It prevents steam from coming in contact with a pressure instrument, which also helps prevent or reduce damage from rapid pressure changes.

How does a gauge siphon work?

Gauge siphons in San Jose, CA are also called coil siphons or pigtail siphons due to their resemblance to the curly tail of a pig. While this may be a cute name, this small, low-cost device is a seriously useful piece. So, how does it work?

A pressure gauge siphon is designed to redirect pressure and heat away from a pressure gauge. One end of the siphon gauge connects to the gauge socket on a Bourdon tube, and the other connects to a temperature gauge.

Before connecting a pressure gauge siphon, a little bit of water is inserted into it. This water sits in the “curl” of the siphon and acts as a condensate. When you want to measure steam pressure of a boiler, for example, the boiler is turned on and the steam rushes into the siphon before it hits the temperature gauge.

That little bit of cool water in the siphon acts as a barrier from the rush of steam and dissipates the heat of the steam through the “curl” of the pigtail. In addition to protecting the equipment, this saves money by allowing for the use of a pressure sensor with a lower temperature range, which is typically less expensive.

Gauge siphon pressure and temperature ratings

Gauge siphons have different pressure ratings depending on their material. For example, gauge siphons made of brass may have a low pressure rating of 250 PSI, with a temperature rating of 400 degrees. On the higher side of the spectrum, a pressure gauge siphon made of 316 stainless steel, schedule 160, may be rated to handle a max PSI of 5,600, with a temperature rating of 500 degrees.

There are different pressure and temperature ratings in between those two extremes, however. The important thing is to choose the right gauge siphon for the job based on the specifications of the device.

If you’re looking to install a pressure gauge siphon in a project you’re working on, it might be helpful to consult your parts vendor about specifications and availability to make sure you get the job done right the first time. To get more information about pressure gauge siphons, or if you’ve got all the info you need and you’re ready to get the right part right now, visit or call Royal Brass Incorporated to get your desired gauge siphon in San Jose, CA today. We have nearly 70 years of experience providing area customers with the hose equipment they need, and we look forward to assisting you soon!

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