Gas-Actuated Thermometers: When to Use Them

If your application is impacted by a wide temperature range or harsh vibration, you need temperature-measuring equipment that can withstand the extreme environment. You must also be able to read the temperature safely away from dangerous conditions.

Otherwise, you may risk equipment damage, which can lead to downtime for your business.

So, what temperature instrument is best for these situations?

This article will discuss gas-actuatedthermometers, when to use them and the advantages they can offer your application.

Using Gas-Actuated Thermometers

Gas-actuated thermometers have multiple advantages, including their ability to have a wider temperature range from -320 to 1,200 °C. They are available as either direct or remote mount.

Remote mount thermometershave a greater resistance to vibration and allow operators to take measurements safely from a distance. Electric contact switches can be added to the thermometer for process alarm or control.

Remote mount thermometers come with capillary line between the case and sensing bulb that can measure up to 80 feet, which allows the thermometer to be installed in low or high places away from the temperature source. This makes gas-actuated thermometers ideal for places with extreme hot or cold temperatures, where it’s not safe for people.

远程气动温度计也阻力t to vibration since the case is mounted away from the process. Direct-mounted thermometers risk damage to the case, scale, pointer and internal parts from the effects of shock, vibration or excessive heat that may be present at the temperature source.

This allows dial reading from locations where personnel are unable to approach due to a hard-to-reach temperature source, obstructions or harsh environmental conditions. Remote mounting is also desirable to bring the dial to a control panel away from the process location.

Thermometer Bulb Types

The bulb is the sensing element at the tip of the thermometer that reacts to temperature changes. Gas-actuated thermometers are available with various styles of plain bulbs or union connection bulbs. The entire thermometer, including the bulb, head assembly and capillary tubing (on remote types), is filled with an inert gas, which offers fast response and linear dial graduations.

Plain bulbs are those without threaded fittings for sensing air or liquid temperatures in open tanks, vats, sinks, etc. Union connected bulbs have threaded swivel nuts that hold the bulb into a bulb fitting such as a thermowell, bushing or flange.

For high pressure or corrosive applications, the use of a thermowell is highly recommended. In addition to protecting the thermometer, thermowells facilitate removal of the thermometer without having to shut down the entire system.

Ashcroft offers electrical contacts with most gas-actuated thermometers to control process temperatures. Electrical contacts can be configured as high and low, double high, double low, “OFF” at low and high, “ON” in between, single contact normally closed and single contact normally open.

Typical Uses of Gas-Actuated Thermometers

There are a number of applications and industries that are suitable for gas-actuated thermometers:

• Offshore oil rigs
• Chemical and petrochemical plants
• Water and wastewater temperature control
• Pulp and paper
• Refineries
• Power
• General industrial
• Equipment skids
• HVAC
• Pharmaceutical/biotech
• Food and beverage

We don’t like to pressure you, but we have more information.

Now that you understand the advantages of gas-actuated thermometers and when it’s appropriate to use one, you should be able to find the best temperature solution for your application.

Ashcroft’s gas-actuated thermometers provide easy-to-read temperature measurements on a dial indicator without the use of mercury.

To learn more about temperature measurement instruments, here are some related articles:

• Choosing a Bimetal Thermometer: 5 Factors to Consider
• Fitting a Thermowell to Bimetal Thermometers or RTDs/Thermocouples
• What is a Thermowell Wake Frequency Calculation?
• How Much Do Industrial Bimetal Thermometers Cost?
• How Much Do Thermowells Cost? 5 Factors that Influence Price

You can alsoreach out to our specialistshere at Ashcroft if you have questions about temperature measurements or instrumentation.