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Unexpected items in the bagging area
You’ve put a lot of time and effort into your food manufacturing process. You’ve sourced your ingredients, prepared and processed them to your own high standards and those of your industry and now you’ve reached the final hurdle – getting them into the hands of your customers in perfect condition and presented in the best possible way to help you stand out from every other product on the shelves. Packaging design is a critically important part of this, it’s your brand’s message and your differentiator, but it can also be a highly technical challenge too. Modified Atmosphere Packaging (MAP), sometimes known as gas flushing, is one way of protecting and prolonging the shelf life of a huge variety of food items.
Air is all around us and many living things need it to survive, but in contact with food it can allow some undesired processes to take place. Air itself is a mixture of gases, mostly Nitrogen and Oxygen. Nitrogen is inert, it doesn’t easily react chemically and in a biological sense it doesn’t promote the growth of aerobic bacteria, yeasts or moulds that exist in the food, in Air and all around us. Nitrogen can almost be thought of as a gaseous void filler and is sometimes used in pure form to provide mechanical protection for fragile items like potato crisps. Oxygen on the other hand can interact chemically with the food, Changing the appearance or causing fats and oils to turn rancid. It also provides a supportive environment for aerobic life to thrive.
If Air is a gas mixture that has some unfortunate properties, then replacing it with mixtures of other, more beneficial gases that can help to prolong the shelf life and maximise profit for retailers is a logical solution, and that’s MAP. Common choices for MAP gases are mixtures of Carbon Dioxide and Nitrogen or Carbon Dioxide and Oxygen. Carbon Dioxide prevents bacteria and fungi from reproducing and reacts with water to form carbonic acid. This mild acidity has a preservative effect on the food. Oxygen makes another appearance, this time in a positive light. With Carbon Dioxide keeping a lid on unwanted bacterial and fungal growth, the ability of Oxygen to keep good colouring in red meats can shine through.
In terms of supply modes, MAP gases optimised for specific foods are available pre-mixed in cylinders from all the major industrial gas companies, and for larger food processors gas mixing on site is an option. This can add a further layer of flexibility by allowing you to adjust the MAP gas mixture to suit the unique characteristics of your own products or even to easily allow your existing machines to handle products with differing in-house or retailer MAP specifications.
Now for the mystery – how can the gas mixture measured in the pack sometimes not match the mixture provided by the supply system? Maybe your gas analyser shows the Carbon Dioxide – Nitrogen mixture you expect to see, but somehow there is also Oxygen? Maybe some of the Carbon Dioxide you know is going into the pack has ‘disappeared’? It’s of course well known that some foods will absorb an amount of Carbon Dioxide over time, but if you are seeing problems with packs fresh off the machine, then there may be something else going on. Before delving any further, the first thing to do is to be sure of your gas analysis from the pack. When was your gas analyser last calibrated? Do you have a certified close-tolerance calibration gas at the correct mixture on site that you can check the gas analyser against? If the analyser checks out ok, then the next question to ask is how can the MAP gas mixture change? Quite often, the answer is that the Air you have tried so carefully to exclude is somehow finding its way into the packs anyway. There are some potential causes that are more obscure than others. In the past we have seen cases of foods that have natural internal cavities, for example prepared whole fish, trapping air inside those cavities as they are packed, which is then released into the pack environment contaminating it with Air. Packing machines often have internal buffer tanks that are replenished between cycles from the wider gas supply system in the factory. Sometimes despite nominally being at a pressure much higher than the surroundings, a leaking pipe can suck in Air if the gas inside the pipe moves at high velocity, for example when re-filling a buffer tank. Probably the most common place for Air to get in though is during the packing cycle on the machine itself. Think of it this way: your packing machine has a few seconds within the packing cycle to displace as much Air as it can by injecting your chosen MAP gas. There just isn’t time for that to happen 100% perfectly, so it’s not so much that Air is getting in, more that it is simply not getting removed in the first place. We might call this the Gas Purge Efficiency of the packing machine, something that can be certainly optimised by adjusting the machine cycle but is unlikely to ever be perfect.
Let’s look at an example, suppose your MAP gas mix was 30% Carbon Dioxide in Nitrogen. Remember that gas mixtures have tolerances too, but for this example let’s assume it’s perfect. Despite what we know the MAP gas mix to be, your calibrated gas analyser shows a mixture of about 2.1% Oxygen, 27.3% Carbon Dioxide and the remainder Nitrogen in the packs themselves. What’s going on?
The composition of mixed gases is conventionally described on a volume basis, so we could instead think of the percentages as some unit of volume instead; a litre or a teaspoon, it doesn’t matter if they are all the same. We know our mixed gas is 30 ‘volumes’ of Carbon Dioxide and 70 volumes of Nitrogen, but our analyser can only see a Carbon Dioxide percentage of 27.3%, so there must be more than 100 volumes of some combination of gases in our pack. If we divide the known volume of Carbon Dioxide by its percentage in the pack atmosphere (30/27.3), we learn that there are 1.098 x the number of gas volumes in the pack than we thought. This means we have 100 volumes from our MAP gas, and about 10 volumes of some other gas. The first suspect is going to be Air that hasn’t been flushed out by the packing machine or was trapped internally in the food as it was packed.
As a check, what can we learn from the Oxygen that has been detected by the analyser? As mentioned above, Air is a mixture of gases, and that mixture is fairly constant. Near sea level, dry Air is 20.95% Oxygen, 78.08% Nitrogen and the last 0.97% or so is made up of Argon and a handful of other gases in amounts so tiny we don’t really need to consider them. If the pack mix has 2.1 volume units of Oxygen, and Air is 20.95% Oxygen, then (20.95/2.1) we see again that we must have about 10 units of Air.
We could say that our hypothetical packing machine has a Gas Purge Efficiency of 91% as it leaves 10 units of Air behind for every 110 total gas units in the finished packs.
The same kind of analysis can be applied to Carbon Dioxide – Oxygen mixtures for packing red meats. If there is more Oxygen and less Carbon Dioxide than you expect to find in the packs fresh off the machine, go looking for Air!
Can this be improved? This probably depends on the control system and design of the packing machine itself – maybe the purge time or purge flow rate can be increased slightly, or maybe the machine would benefit from some maintenance intervention or recalibration if this is a new package size? Another approach, if the Oxygen is at or below your accepted tolerances and you just need to get a bit more Carbon Dioxide into the packs is to simply increase the Carbon Dioxide component of the MAP gas at source until you get where you need to be. A common starting point is to increase the Carbon Dioxide component to nearer 33%, giving closer to a perfect 30% in the pack in the worked example above.
In all cases, your food packing machine manufacturer and your gas supplier will be glad to help you resolve these issues.
Got your liquid gases? Want mixed gases? We do the bit in the middle….
Even those without a day-to-day technical knowledge of Gas Distribution Systems can appreciate what a high-pressure gas cylinder is. They may not know the complexities, dangers and exact background of what it is and how it is produced and exactly what high pressure really means, but most people have seen one somewhere. They are very common in pubs, bars and restaurants. Fast food restaurants and swimming pools and of course most manufacturing facilities. People also see smaller units in their homes for oxygen for example and more recently now, many have a greater understanding of the importance of oxygen cylinders in hospitals.
Gas cylinders are of course available in many different sizes and weights and are filled with all sorts of gases and increasingly, all sorts of gas mixtures. Mixtures of CO2, Nitrogen and sometimes Oxygen for the beer, beverage and food packing applications. Mixtures of CO2, Argon, Helium and hydrogen for fabrication applications, welding, heat treatment. Mixtures of Helium for blowing up balloons and leak detection in pipelines. Just a few examples of the many common everyday uses for gas cylinders or bottles as they are sometimes referred to.
For those businesses that begin small and evolve organically, industrial gas cylinders are a relatively simple starting point to early production. They are convenient to begin with and readily available from several of sources. And the chances are that the mix you need is already a common mixture supplied to many others. But as businesses grow, they may be fortunate to reach a point where gas cylinders don’t quite fulfill their new needs. And this can be for a few obvious reasons.
Cost is possibly the first factor users begin to question. With gas cylinders you generally pay for the gas inside the cylinder of course. But there are also costs associated with rental of the cylinders all the time you have them. There are most commonly charges associated with delivery of the cylinders and the removal of spent cylinders and so on. And you need to know that you have available to you back-up cylinders and a steady supply so that you don’t run out.
Convenience is possibly the next factor to wrestle with. There is the convenience of matching gas cylinder orders against production demand or need. There is the convenience of handling each gas cylinder and getting each cylinder to its point of use. And there is the convenience of trying to control the safety aspects of handling, connecting and disconnecting. The cylinders are heavy, they must not be dropped or damaged, they must be secured, and handlers should have some basic training in these aspects.
Choice is also a significant factor. Whilst there are many gas cylinder suppliers, they have their own restrictions, and it is not always possible to obtain the exact mix you need. And sometimes if you can get hold of it, you cannot always get hold of it without paying a premium.
Continuity also is an issue. Being able to continue to grow the business using gas cylinders as the source can simply become too difficult, too cumbersome and too labour intensive. The process of supplying cylinders can begin to be a bigger issue than other, more important parts of the process.
These factors are greatly over- simplified of course, but, whatever the combination of events or reasons, as gas demand increases, there will be a point at which it becomes interesting to consider being supplied with liquid gases, delivered into your liquid gas tanks. There are again several suppliers that can deliver liquid gas supplies reliably.
Liquid gas supplies are generally delivered on a pre-determined delivery schedule in much larger volumes directly into liquid tank storage systems. The cost basis is quite different from cylinder delivery of course, so this needs to be understood, however the unit costs for gases is much less, the more you use. And importantly a lot of the pressures mentioned earlier become much easier for the end user. Often the liquid tanks are away from the main factory or process and much more clearly the responsibility of the gas supplier. So, if the costs stack up for you, liquid gas supplies take a lot of the day-to-day handling away from the end user.
Of course, that still leaves one or two other factors such as choice and continuity to contend with. But having a liquid gas supply of each gas available makes those things easier too.
Once you have your liquid supplies in place, they are either supplied to the plant as they are. Or they can be mixed together, to create the exact mix or mixtures you need for your process.
This is where a Gas Mixer from BSL Gas Technologies Ltd comes in to play to help with continuity and choice.
Mixed gas choice – Unlike with premixed gases in cylinders, the BSL Gas Mixer provides the opportunity to choose the gas mix needed for the process. The process can be presented with a pre-set gas mixer or with an adjustable mixer. Some gas mixtures are common. In the beverage/beer industry for example 30% CO2 in nitrogen and 60% CO2 in nitrogen are mixes you can often obtain in cylinder format.
Anything else is very difficult to obtain cost effectively. But the BSL Gas Mixer will give you a much wider range to choose from. If you need anything between 20% and 80% CO2 in nitrogen for your beers for example, the gas mixing valves will happily provide this, and the mixer cost is not affected by the mix required.
The benefit of a BSL pre-set gas mixer is that there is great control over the process integrity. Whilst even a BSL pre-set gas mixer can be adjusted. It is deliberately difficult for unauthorized changes to be made. There are often tamper evident labels over the gas mixing valves also.
The benefit of a BSL adjustable gas mixer is that the end user can change the mix as they desire to meet different process demands. Food packing companies for example often ask for adjustable gas mixers for different packed products, although even in this situation often a food packing plant packs a range of similar products with similar mixed gas requirements.
And when designing a process plant, how you deliver mixed gas variation but at the same time still keeping control over the integrity of that installation can be accomplished using BSL Gas Mixing modules in a clever way. BSL can help you to figure this out exactly.
Continuity and growth of the process – This is an important element of any mixed gas distribution system. Whilst there will be a predictable flow requirement to begin with, it is often more difficult to predict future growth and demand. This part of the planning process is difficult because it has a knock- on affect to any equipment installed including the pipelines, valves and regulators, liquid tanks and the gas mixer also.
With liquid gas supplies, tank sizes can be increased over time and additional pipelines can be added from them to the process as needs require it. The BSL gas mixer can also be easily upgraded.
BSL have developed a very modular approach to designing gas mixers. Deliberately simple, it is possible to add mixing valve modules into existing gas mixing panels. And it is equally easy to add mixing panel modules to work alongside existing mixing panel modules.
That way you can install BSL mixing panels equipment as you require it. No need to purchase something much bigger now, for a guessed much bigger flow later. It is very common for our customers to simply extend their installations, when they feel they need to.
BSL Gas Technologies Ltd have been designing and making Gas Mixers and Gas Analysers and Gas handling equipment for more than 30 years. A significant leap forward in BSL designs was our ability to take the electrics and buffer tanks out of the system for you. Simplifying installations, reducing the number of things that can fail and making systems very easy to look after. And we know we have been very successful at that by the number of imitators we have.
The simplest of systems take your pure gases, vaporize them into gases or they may already be gases if they are from cylinders or MCP, and provide a regulates and protected supply to feed a BSL gas Mixer. The mixer in turn, mixes the gases proportionally as a pre-set mixture or as an adjustable mixer to give you the mixed gases you need.
It can be challenging to find school leavers that already have had an experience in engineering to work in a factory environment. We need good quality engineers to ensure the strength in our company and give future engineers a real chance.
In the last few years, we have taken on 4 young people and have decided to train them ourselves, together with help from the local technical colleges.
The first two apprentices have done their time and in doing so, have covered all the skills necessary to be able to undertake every job and project in the factory with skill and dexterity.
Today Aidan and Lewis are now running the factory, controlling standards and training others as they go.
This has allowed other more experienced personnel to progress through and spend more time on developing more and better products for our customers.
And it has also allowed us to create 2 more apprentice positions for Hannah and Ryan to repeat the process and keep the company stocked with knowledgeable and driven personnel, even though they may not have started in Engineering in school.
Re-enforcing that, we have also been able to strengthen our Engineering team, adding Julian and his huge experience over 30 years in engineering.
We do not plan on stopping there either. Watch out for more growth at BSL!
Expanding on our great range of Gas Analysers!
The BSL View-Mix range of wall mounted gas analysers have a new member in the family. It is the View-Mix AW201RANNN unit, 0-100% CO2 in N2 Gas Analysing system.
Ideal for use with beer, beverage, and food packing applications where CO2 and Nitrogen are being mixed by a BSL Gas Mixer. The View-Mix unit will keep an eye on the mixed gas in your pipework. It has a digital display, programmable alarms, and a 4.20mA output signal, you can feed into your existing production monitoring system. You can monitor Gas Mixers, tanks of product, pipelines and even cylinder filing systems.
Spencer Cai started A-GES Suzhou after a successful career working for Linde Group. He has built an excellent team working out of Suzhou, a good drive from Shanghai in China.
A-GES of China are pleased to be working with BSL for more than 10 years now.
Spencer says he is very pleased to have been working with BSL for such a long time. He is particularly pleased with the robust nature of BSL equipment over time. It truly is very reliable and needs very little looking after. It makes it easier to establish a long-term brand image for BSL, which Spencer has been very successful at doing.
He had customers that have had ongoing mixture problems with other European suppliers. Whereas these problems were instantly fixed with a standard BSL panel. He also had customers that have spent no time at all maintaining the BSL mixing panels. After 10 years, they are still amazingly working perfectly, and Spencer found that to be very impressive.
Thank you, Spencer, from BSL to the growing team at A-GES, for your hard work in the last 10 years. Long may it continue.
Spencer also told us about a customer from Yingde Gas, “They bought two FW4 BSL mixers and installed them in 2011 in North China. It has been in operation for 9 years without any trouble. Earlier this year Yingde Gas were worried about the working years of the mixer being too long and invited Charlie and I to go to site for an inspection. After analysing, the results were amazing. This really touched and amazed the customer and helped us to establish the BSL brand image”.
If you are in China and need a gas mixer or gas mixing equipment, please contact Spencer and his team. They will be very pleased to hear from you!
The CF5000 package is an extremely versatile Gas Mixing Package, it has been used in a number of ways for a number of different applications.
The package has three key parts. The Gas Mixer, the Gas Analyser, and the stand itself. The first part is the Gas Mixer, which uses the BSL Mass Flow Control Valves to make the mixed gas. These are well suited for this application, not least of all because they have a low pressure drop across them to produce high flows. What this means is that they can supply high flows of mixed gas even when you have some gases coming from other than liquid gas sources.
Nitrogen is increasingly delivered from Nitrogen Generators and this tends to be at pressures less than 10 bar g. The BSL Mass Flow Control Valves are perfect for this type of application.
The Gas Analyser is an optional item to back up the adjustable gas mixer. We have several options. Starting with a simple display and alarms to a more complex display, alarm, and output signals for use with your existing Management Control Systems and software for recording and reporting.
The third part is the very robust stainless-steel stand. It is deliberately made this way so that it can be washed down with cleaning fluids that will not damage it in any way. Those that would benefit the most are therefore food and beverage factories, where everything must be cleaned down periodically. The stainless-steel stand will cope with all the usual cleaning fluids.
In one particular Brewery, this package has been used in a number of areas of the plant. It has been used to feed the Keg Racking Area. Another unit has been used for blanketing the storage vessels. And outside of the factory another unit has been used to create the mixed gas to fill gas cylinders of beverage dispense gases reliably and accurately. Very versatile…
Service– As with all gas installation equipment, periodical servicing, replacement of parts or calibration is required to keep the systems in top condition. The BSL Gas Mixing systems are often overlooked as they consistently supply mixed gas without faults or issues.
Exchange– We have many customers that are now holding stock of calibrated panels that they simply exchange on a yearly basis. They then send the panel they have removed to us for re-calibration.
Our panels are simple to exchange, normally only taking 15 minutes to unscrew 3 or 4 nuts and screws, its as easy as that! Our panels are simple, versatile, easy to maintain and very effective. We can take all the fuss out of your auditing process!
Rental– If you prefer, instead of holding an exchangeable stock of panels, we can rent you one! Our range of panels are readily available upon request. We can set up a date with you to receive the panel with rental over an agreed short period, whilst yours is being calibrated.
Upon return of your newly calibrated panel, you then place the rental panel in the box, ready for collection. It could not be easier than that!
We have been making our FW Gas Mixing Panels for over 15 years now. They have proven to be very popular with a lot of our customers. They deliver exactly what we say, reliably.
We Listened when our customers made suggestions of how to improve installations and site work. We looked at reducing the time that engineers were on site and what equipment would benefit our customers.
We introduced a simple effective system called the FWX assembly which consists of: A floor stand and correctly specified gas filters with additional options including Leak Detectors and relief valves. These were designed to go with our FW Gas Mixing panels and help to consolidate equipment into a neat package. As it is floor standing there is no need to drill holes in the walls. This set-up can be mounted outside as well!
With all the benefits of the original pressure mechanical design that everyone likes (no electrics, no buffer tanks) added to greatly reducing installation time on site. It is a great package for many industries!
Perfect for integrating into your existing process and easy dismounting for when you have equipment re-calibrated. We have a rental program available, so you do not have to be without a Gas Mixer while yours is being calibrated. Ask us for more details!
The Gas-Mix GMB family of gas mixers has proven to be a very popular design for a number of applications and has been available for 2 gas pre-set mixtures of all the common gas combinations.
Responding to an enquiry from one of our longest standing customers of 25 years, our engineering team have taken the standard design and made it twice as useful for them and for you of course.
Added to the family is the Gas Mix GMB ‘dual’ pre-set outlet gas mixer. The dual outlet means that your customers can select one of two pre-determined mixtures to perform their application with, from a single mixing panel.
Two pre-set Gas Mixers in one unit!
For example, you may be a small food packing company that needs a 30% CO2 in N2 gas mixture, but they have customers that prefer 40% CO2 in N2. The Gas Mix GMB dual mix will allow them to select between the pre-set mixtures as and when they need to. Both mixtures will be calibrated and certified using known high specification certified calibration gases.
Of course, the great thing about certified calibrated pre-set units is they are a known standard and cannot be altered accidentally by unknowing plant operators. It gives them some choice, but you still maintain control over the final gas mixture.
If your customer does want fully adjustable systems, then we have those available too, but the dual mix system maintains control by providing flexibility but limited to your absolute needs.
Particularly for small users of gases, it provides the opportunity to keep costs down by purchasing pure gases in cylinders or bulk liquid storage and having the capability to work between mixtures for different products.
The customer will be confident the panels are calibrated to BS EN ISO 14175;2008 standards of mixed gas accuracy, and able to switch between mixtures in complete confidence. Switching between the mixtures could not be easier either; there is a simple mechanical selector valve on the front of the panel, clearly labelled.
If you are a small user or supply small users of gases that need a little more control but not too much, let us know what your application is and we will happily provide the details of the Gas Mix GMB twin mix system to you. You can email us here.
We are proud to announce a brand-new addition to our MFCV family!
In our existing range there are various sizes such as 30, 500, 1600 and 5000 ltr/min @ 14 bar g. These are commonly used for gases such as CO2, N2, Ar, He, H2 and clean dry air but now we have added O2 to that list!
We have had increasing interest and requests for oxygen versions of our popular MFCV’s. So, in response, we are pleased to announce our new BO396 which is now compatible with oxygen! It provides 1600 ltr/min @ 14 bar g (1100 ltr/min @ 7 bar g) and has a built-in needle valve so you can adjust the flow rate. It is fully pressure mechanical and can be mounted to a panel or supported in pipework.
Our MFCV’s are a mechanical valve that is very good at maintaining the flow through with a constant supply gas pressure but varying downstream pressure. It is suitable for anywhere that you need to maintain that flow, given the downstream pressure is changing, filling a buffer tank for example.
This overcomes the fundamental problem of using a simple orifice flow device. With a simple orifice, the flow of a given gas through it will change as the pressures to and from it change. Or as the differential pressure across it changes.
The BSL Mass Flow Control Valves are part of a great solution to deal with this. As you may know we have an established family range of valves for inert gases and hydrogen.
Examples for applications where controlling flow in this way is very useful are gas generators, tank blanketing, gas mixing and anywhere the downstream pressure fluctuates greatly.
The NEW BO396 designed for oxygen use is available now along with our existing range of valves! They also have an improved warranty of 7 years as these have proven to be reliable and hard-wearing.
If you have an application that needs greater flow control of gases with downstream pressure fluctuation, for more details email us.