Fixed gas detectors are used for continuous monitoring in permanent work environments. Portable gas detectors can be worn by first responders and maintenance crews in the field. Both options issue an alarm when the target gas or gases passes the acceptable threshold.
Gas monitoring is essential for any business encountering potentially hazardous gases, including carbon monoxide, methane, nitrogen dioxide, and combustibles that can lead to flash fires. Breathing in these gases can lead to various health complications and symptoms, including dizziness, nausea, fatigue, shortness of breath, loss of consciousness, and increased risk of various types of cancer. Companies can use fixed or portable gas detectors to monitor the amount of gas present and lack of oxygen in the air, so workers at risk of exposure can either vacate the space during a gas leak or don the appropriate personal protective equipment to protect themselves from serious injury and illness.
Choosing between portable vs. fixed gas detectors depends on several factors. Use this guide to find the right type of gas detection equipment for your team.
Fixed vs. Portable Gas Detectors: Similarities
Let’s start with what they have in common.
Both options monitor the concentration of the target gas or gases in a variety of spaces. However, portable gas detectors are typically used in the field where gas levels can be unpredictable, while fixed gas detectors are used in permanent workspaces that require around-the-clock monitoring.
Both use electrochemical sensors that create a chemical reaction when exposed to the target gas, which is then converted into an electrical signal displayed on the LED panel. They display the target amount as a percentage of the total air supply. Hazardous gases are measured in parts per million (PPM). The alarm activates when the target gas surpasses the permissible exposure limit (PEL) or lower explosive limit (LEL), the point at which the gas can spontaneously combust, or when oxygen levels are low.
Portable and fixed gas detectors can detect one target gas or multiple gases based on the amount of oxygen in the air. A gas monitor that only detects one type of gas is known as a single-gas monitor, while one that detects four or more gases is known as a multi-gas monitor. A multi-gas monitor contains a separate sensor for each target gas. The most common sensor configuration for a multi-gas or 4-gas monitor is carbon monoxide, hydrogen sulfide, combustibles, and oxygen.
Both detectors need a bump test at the start of every shift by exposing the sensor to a gas cylinder tube with a known target gas concentration. Bump testing verifies that your gas monitor is working properly to detect the target gas in a work environment. If the results do not match the readings on the cylinder, the device must be recalibrated. Calibration is necessary to check the accuracy of your readings. This is especially important for older devices because the sensors can degrade over time and use. Devices that can’t accurately read set values need to be replaced. Any devices that have been dropped or otherwise damaged should be recalibrated. We recommend calibrating at least every 6 months. When in doubt, refer to the owner’s manual and manufacturer’s guidelines.
Fixed vs. Portable Gas Detectors: Differences
Portable Gas Detectors
Portable gas detectors are designed to be worn, so workers can keep their hands free. They usually only weigh a few ounces.. Each has a clip that quickly attaches to a collar, lapel, or bag of the user. The device should be worn in the breathing zone or within 10 inches of the person’s nose and mouth. This ensures that the sensor is exposed to the same air the person is breathing; otherwise, the results may be inaccurate. Some gases sink or rise depending on how much they weigh compared to the surrounding/ambient air.
When gas levels exceed the permissible threshold, the alarm vibrates, flashes, and makes an audible noise to alert workers in loud spaces or those with poor visibility.
All portable gas detectors run on batteries that usually last up to 24 hours. The device lists the battery charging time and how long it will last when it’s on or in standby mode.
Companies can store their portable gas detectors in a docking station in between shifts. The station automatically recharges the battery, performs a bump test, and recalibrates the sensor when necessary while documenting the results.
Fixed Gas Detectors
Fixed gas detectors are installed permanently in a variety of work environments and confined spaces where hazardous gases can gather. They are designed for continuous gas monitoring and typically must be plugged into a power source. The monitor should be installed at the proper height depending on whether the gases rise or sink to the ground. Most gas detectors are mounted on the wall’s ceiling or ground to keep them out of the way and ensure they do not obstruct the working space.
The detector has a limited range. Companies must install a fixed gas monitor every 30 to 40 feet in large, enclosed settings to monitor the air in the space.
Fixed gas detectors may have a wireless option and can connect with smart devices in real time. Each device reports to a central control panel or software program that automatically records the readings for compliance purposes. If one monitor detects a high gas concentration, the other monitors in the area will activate their alarms to ensure workers evacuate safely.
The latest technology makes it easy for managers to monitor dozens of devices and work zones at the same time. Using the interface, they can file incident reports, contact specific workers, and identify individuals who may be at risk of exposure based on their proximity to the affected monitor.
How to Choose Between Fixed vs. Portable Gas Detectors
Both monitors have specific uses in various industries. Workers in confined spaces typically utilize portable gas detectors to avoid potential exposure. First responders, utility crews, and maintenance professionals generally use portable gas detectors when working in the field. This helps them stay prepared and flexible when visiting various locations on the job.
Companies with hazardous gases present in warehouses and facilities should install fixed gas detectors in these enclosed spaces where these gases can gather, including oil and gas plants, agricultural facilities, pipelines, and manufacturing plants.
Choosing the right gas monitor helps save lives. Contact the professionals at PK Safety to find the right gas detector for your company.