Maintaining SF6 Measuring Equipment: Why Is It Important?

Sulfur hexafluoride (SF₆) gas has many uses, primarily in the electrical industry. Utilities use SF₆ gas for gas-insulated equipment (GIE) and arc quenching with high-voltage circuit breakers and switchgear. It has multiple other industrial applications, such as in the production of magnesium and semiconductors.

Given its many uses, SF₆ is a precious commodity for electrical transmission and distribution. However, it is also a potent greenhouse gas. SF₆ emissions due to improper handling techniques or leaks in equipment contribute to climate change. Measuring equipment, such as SF₆ analyzers or leak detectors are an essential part of emission-free gas handling. All SF₆ service equipment requires careful maintenance.

The Importance of SF₆ Measuring Equipment Maintenance

One very important aspect of preventing SF₆ emissions during gas handling is to ensure that all equipment used on the job site is in good, working condition. That’s where maintenance comes in! DILO understands the importance of emission-free gas handling. In addition to offering a range of high-quality SF₆ gas products, we also offer numerous gas handling services through DILO Direct.

Part of DILO’s mission is to educate SF₆ users on how to properly use and maintain their equipment in order to prevent SF₆ gas emissions. Maintaining equipment is such an important part of preventing emissions that we’ve decided to dedicate an entire blog series to this topic.  Below, in part 2 of this series, we’ll explore why proper maintenance of measuring equipment matters.

Understanding Standard Maintenance for Measuring Equipment 

There are several types of SF₆ gas equipment, each requiring adequate maintenance to continue working properly. In this blog post, we are focusing on measuring equipment. This category includes analyzers, density monitors, and leak detection equipment. Staying on top of routine maintenance will extend the life of your measuring equipment.

SF₆ Analyzer Calibration Intervals 

SF₆ analyzers are what measure the quality and purity of SF₆ gas. They measure the different elements of gas, including:

• CO concentration
• SF₆ volume percentage
• H₂S concentration
• Moisture concentration
• HF concentration
• SO₂ concentration

SF₆ gas analyzer calibration is necessary to ensure proper readings. On average, our SF₆ analyzers must be inspected every two years. It is important that calibration is performed by a well-qualified technician as improper calibration can cause a range of issues including exposure to arc by-products, faulty readings, and damage to the device. The earlier a device is maintained, the sooner any potential issues will be detected. During inspections, professionals conduct SF₆ analyzer calibration and inspect and exchange the following sensors:

SO₂ Sensor Exchange

An SO₂ sensor detects sulfur dioxide levels for gas measurement. Efficiency is measured as a percentage through a method called “span reserve.” If an SO₂ sensor exchange scores below 50%, it could be an indication that it may be time for a replacement. During inspections, professionals will recalibrate the sensor, among other tasks, to ensure the equipment works properly. SO₂ sensor exchange should occur at least once every two years.

H₂O Sensor Calibration

H₂O sensors are designed to detect moisture levels in a supply of SF₆ gas. When SF₆ gas becomes infiltrated with too much moisture, it can render the gas supply unusable. H₂O sensors must be calibrated every two years to remain efficient in detecting moisture.

Volume/Purity (%) Calibration

SF₆ gas produced commercially has a minimum purity of 99.9%. A gas purity meter will calculate SF₆ purity as a percent (%) of the volume. Leaks, arcing events, and improper gas handling procedures can cause SF₆ by-products to form. SF₆ by-products are a hazard to human health and SF₆ maintenance equipment.  Depending on the concentration, toxicity, and reactivity of these impurities, they can significantly affect SF₆ and alter its application with insulation and arc extinguishing. To ensure accurate readings, these measuring devices should be calibrated at least once every two years.

Analyzer Compressor Test

Compressors are designed to decrease the volume of gas, which pressurizes it and allows it to run through technology. Compressors are essential to keeping equipment running, making it important to inspect and maintain them regularly. Compressors should be tested every 500 hours of operation. Compressor tests are a routine part of an analyzer calibration.

Storing Measuring Equipment 

Another part of efficient maintenance is the proper storing of SF₆ measuring equipment. Failure to store equipment properly can decrease its life and cause breakdowns to occur sooner and more frequently. Knowing the correct equipment storing protocols can extend the life of your gas-handling equipment and make the most out of your investment. Below are a few important storage considerations for SF₆ measuring equipment:

Store Under Vacuum

Did you know it’s important to not store equipment pressurized with gas? A small amount of gas will be left inside the device and connected hoses after a gas sample is analyzed. It’s necessary to depressurize the gas in an analyzer using the special function “evacuation of device”. Be sure that the analyzer is connected to an external recovery bag or a cylinder to prevent any emissions.

Optimal Temperature

The optimal storage temperature for measuring equipment is -10 to 60ºC, or 14 to 140ºF. The storage temperature is a wide range; However, conditions in the field could cause measuring devices to be exposed to temperatures outside of this range. Therefore, we recommend storing measuring equipment indoors when not in use.

SO₂ and H₂O

If high H₂O levels are detected in a gas sample, it is necessary to dry the device before storage. This is done by selecting “drying of device” under special functions. If high SO₂ levels are detected in a gas sample, it is necessary to clean the device by selecting “purging of SO₂ sensor” under special functions.

Battery

Battery charge is an important storage consideration. It’s best to avoid a complete draining of the installed battery of any measuring equipment. If stored at 100%, charge the battery after a maximum of 6 months of storage. A minimum charge of 30% is required before storage. Following these simple tips will help preserve the battery life of your device.

DILO’s SF₆ Gas-Handling Philosophy 

DILO takes a sustainable approach to gas-handling services and equipment. We work with numerous international players in the electrical transmission and distribution industry, including utilities and switchgear manufacturers. Our goal is to help you achieve proper SF₆ gas handling and management to prevent SF₆ emissions.

We aim to ensure businesses can make the most out of their SF₆ gas supply, saving time, money, and resources from replenishing gas. It’s these qualities that make us a leader in the SF₆ gas equipment industry.

Do you have questions about measuring device maintenance or gas handling? Please contact us. Our experts are always happy to help!