Reset & Recalibrate – A Guide to FGA Calibration

Ensuring your flue gas analyser (FGA) is regularly maintained goes without saying, however the hows and whys take a little more digging into. This article breaks down the calibration process and highlights handy tips and tricks for maintenance and best practice. 

 

The Act of Calibration 

Calibrating an FGA involves checking the sensors to ensure accurate measurement of a known concentration of certified calibration gas. To do this, the reading needs to be adjusted to match the gas concentration through an initial sensor calibration of the new or existing unit.

Next up is a calibration drift – this is done using existing instruments to bring the reading back after the drift occurs. Measuring the amount of drift in the gauge is a chance to see how far into inaccurate territory it has moved, and rule out measurement errors moving forward. 

 

Sprint Pro Calibration

Regularity is key

Sensors degrade over time with each sensor having a different life span of optimum operation, whether it is an electrochemical, catalytic bead and infra-red sensors. Regular calibration raises the gain levels and brings the sensor back in line to avoid dangerous incorrect readings. 

Once the sensor reaches a certain point it cannot be brought back into the correct position and this is the time when a new sensor needs to be installed. 

 

Explaining the calibration procedure 

The first step of the process is to set the device to calibration mode. This feeds a test gas of a known concentration onto the sensors to see how they respond. The gain levels are adjusted within the sensor to match the readings to the concentration fed in whilst mitigating drop off. 

The new settings are locked into the device’s firmware and a calibration report is produced, creating a PASS or FAIL result. 

Best Practice Tips and Tricks

Here are some best practice recommendations to help you maintain your FGA.

  • Clear out the water trap regularly – moisture is a by-product of combustion and can get sucked into the FGA when a test is undertaken. Water damage is the primary cause of damage in flue gas analysers, so it is imperative to check, empty and replace the unit’s inbuilt water traps and filters to protect from this.
  • Purge the device in clean air before powering down – noxious gases are drawn from the flue and passed over the sensors to gain a reading. After a test is completed and the system closes down some of that gas remains trapped inside. This can cause corrosion damage and shorten the life of the unit, so purging in clean air prior to shut down is a must.
  • Take inside to protect from cold weather conditions – to lessen the chances of condensation build up and water damage within your FGA make sure to remove the unit from your van overnight. This also reduces the risk of theft. 
  • Use approved chargers with outputs tailored for target device – non approved chargers cause damage to the battery and lessen charge retention, or even impairment to the battery and IC chips of the device itself.  
  • Check the devices’ probes and connector pipes – any splits or cracks in the rubber house will cause incorrect readings. Performing periodic checks on your hoses to ensure they are in good operating condition is a useful habit. 

 

All-Inclusive Service Options 

You have multiple options when sending your device off for it’s annual service and calibration:

Send it direct to us

Crowcon’s innovative Autocal jig system manages the end to end calibration process for Sprint Pro FGA’s. An out-of-calibration unit leads to errors in the combustion reports produced and could disrupt your day to day. 

Autocal servicing is easy. Simply bring your FGA to one of the DPD drop off locations, your unit will be inspected, tested and calibrated within two days and returned to you using DPD’s express return trackable option.

For more information please check out https://shop.crowcon.com/

Send it to your local store

Drop your device in to your local trade counter or specialist servicing centre at a time convenient to you and they will work with us to facilitate the annual calibration.
They will contact you to come and collect your device once the calibration is completed.

Explosion hazards in inerted tanks and how to avoid them

Hydrogen sulphide (H2S) is known for being extremely toxic, as well as highly corrosive. In an inerted tank environment, it poses an additional and serious hazard combustion which, it is suspected, has been the cause of serious explosions in the past.

Hydrogen sulphide can be present in %vol levels in “sour” oil or gas. Fuel can also be turned ‘sour’ by the action of sulphate-reducing bacteria found in sea water, often present in cargo holds of tankers. It is therefore important to continue to monitor the level of H2S, as it can change, particularly at sea. This H2S can increase the likelihood of a fire if the situation is not properly managed.

Tanks are generally lined with iron (sometimes zinc-coated). Iron rusts, creating iron oxide (FeO). In an inerted headspace of a tank, iron oxide can react with H2S to form iron sulphide (FeS). Iron sulphide is a pyrophore; which means that it can spontaneously ignite in the presence of oxygen

Excluding the elements of fire

A tank full of oil or gas is an obvious fire hazard under the right circumstances. The three elements of fire are fuel, oxygen and an ignition source. Without these three things, a fire can’t start. Air is around 21% oxygen. Therefore, a common means to control the risk of a fire in a tank is to remove as much air as possible by flushing the air out of the tank with an inert gas, such as nitrogen or carbon dioxide. During tank unloading, care is taken that fuel is replaced with inert gas rather than air. This removes the oxygen and prevents fire starting.

By definition, there is not enough oxygen in an inerted environment for a fire to start. But at some point, air will have to be let into the tank – for maintenance staff to safety enter, for example. There is now the chance for the three elements of fire coming together. How is it to be controlled?

  • Oxygen has to be allowed in
  • There may be present FeS, which the oxygen will cause to spark
  • The element that can be controlled is fuel.

If all the fuel has been removed and the combination of air and FeS causes a spark, it can’t do any harm.

Monitoring the elements

From the above, it is obvious how important it is to keep track of all the elements that could cause a fire in these fuel tanks. Oxygen and fuel can be directly monitored using an appropriate gas detector, like Gas-Pro TK. Designed for these specialist environments, Gas-Pro TK automatically copes with measuring a tank full of gas (measured in %vol) and a tank nearly empty of gas (measured in %LEL). Gas-Pro TK can tell you when oxygen levels are low enough to be safe to load fuel or high enough for staff to safely enter the tank. Another important use for Gas-Pro TK is to monitor for H2S, to allow you judge the likely presence of the pryophore, iron sulphide.

Working together for safety at sea

Crowcon Detection Instruments is working together with Solent University’s Warsash School of Maritime Science and Engineering – all in the name of teaching engineering cadets, senior Merchant Navy officers, and Superyacht crews.

Solent delivers world-renowned yacht and powerboat design degree programmes, a suite of international maritime studies courses and a wide range of specialist support services for the maritime industry. It is also conducting a large number of research studies that make a real impact on industry thought leadership.

Their partnership with Crowcon makes good sense!  The marine environment is a dangerous one – and not just the more obvious hazards like high seas, storms, or rocks and coral reefs.  Confined spaces on ships, high-risk cargo, and on-ship processes all present potential gas hazards.

To keep mariners safe, gas monitoring equipment is essential.  Gas detection equipment requires specific marine environment testing and certification to ensure suitability to the extreme environments it operates in.  The European Marine Equipment Directive (MED) approval is internationally recognised. Gas detectors used by mariners onboard a vessel registered in an EU country must hold MED approval, and show the wheel mark to demonstrate compliance.

Crowcon has provided the university with demonstration T4 portable multi gas detectors.  T4 provides effective protection against the four most common gas hazards experienced in the marine industry, and is robust and tough enough to deal with the demanding marine environments.  T4 is ideally suited to help vessels comply with multiple SOLAS requirements which dictate the need for gas detection onboard vessels.

John Gouch, lecturer at  Solent University, said: “I have used Crowcon instruments in industry for many years, and know how reliable and trustworthy their gas detectors are. Since joining Warsash 18 months ago, I have been keen to ensure students understand the important part gas detection plays within the on-board safety system.”

“By using demo units of these detectors within our marine engineering courses, we can show the importance of gas detection in a marine environment to hundreds of seafarers and mariners, keeping as many people as possible aware and safe.”

Louise Early, Head of Marketing at Crowcon, said: “We’re really pleased with our partnership with Solent University.  By developing our relationship with training establishments, our safety message gets out to the people who will benefit most. We are always keen to learn from industry and this programme also offers Crowcon further insight into the way in which our equipment is used.”

For more information, visit the Solent University website, or the marine section of our industries page.

Deadly sin no.1- not calibrating

We recently ran a series of articles call the “Seven Deadly Sins of Gas Detection”. By highlighting the most common causes and effects of each ”sin”, we wanted to provide managers and employees with a greater awareness of what we believe are the Seven Deadly Sins of gas detection, how to avoid them and save lives. For the same reason, we are sharing them as our blog posts for the next seven weeks.

Continue reading “Deadly sin no.1- not calibrating”

Planning for shutdown season

Maintenance performed during a site shutdown often takes in gas detection systems, including checking expiry dates and calibration. For some, shutdowns also increase the use of portable and transportable monitors, as fixed systems are being maintained and extra personnel come on site to work.  Every year, around this time, we get a significant increase in calls about problems arising during site shutdown. Many of these could have been avoided with a little planning and forethought.

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Calibration – want to know the basics?

Calibration of gas detectors is vital to be sure that they are in good working order and able to alert the user to gas hazards in their vicinity. A calibration is a “resetting” of the detector’s response against a known concentration of target gas, in a balance of synthetic air or nitrogen. This will determine the relationship between the detector’s reading and the actual concentration of the component gas of interest. Adjustment involves modification of the detectors response to bring the reading into line with what is expected while exposing the instrument to the known source. This is fundamentally different to bump testing which is a brief exposure to gas in order to verify that the sensors respond within a specific boundary and the detector’s alarms function properly.

Continue reading “Calibration – want to know the basics?”

Bump Testing: What do you need to know?

There are many reasons why a portable gas detector may not react to gas, some of which are not visibly evident to the user.  When an instrument is turned on, you can see that the battery and display are working properly, but what about the internal electronics which play a critical role in protection? Do the sensors and alarms all work, have they been inhibited by using the wrong cleaning solution or have their openings become obstructed by mud? How do you know?

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Training – the vital ingredient

Gas detection is a critical safety function in many industries, to protect people from harm and avoid costly plant disruption or damage. Not only must you use a suitable instrument for the task and the environment, but it must be used correctly and maintained properly if it is to fully serve its purpose.

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The simple steps to looking after your gas detection equipment this winter.

Gas detectors are there to save your life, whether it is a fixed system or a portable detector, keeping them well maintained is an important part of ownership.

Our guest blogger this week, Julian, has put together simple steps to ensure your gas detector is up for the job as and when it’s required.

Continue reading “The simple steps to looking after your gas detection equipment this winter.”

Why do we calibrate?

I’ve talked about bump testing your instrument, so it seems natural that we now cover the importance of calibrating.

There are two main reasons for calibration. Firstly, gas detectors often operate in harsh environments: high and low temperatures and/or humidities; they may be exposed to contaminants, such as solvents, silicone etc; gas exposure; as well as the age of a sensor; any of which can result in the degree to which the detector responds to a given gas concentration changing, for example, the detector may read 46% LEL when the true level is 50% LEL.

Continue reading “Why do we calibrate?”