Products in Review – Gas Fuse

gas fuse

Gas Fuse

When the Gas Fuse first landed on my desk I must admit I was very skeptical about the usefulness of this device, given the simplicity of its design. In the interest of fairness, we decided to put it to the test.

At first glance it seems like a good idea. The device promises 4 main functions:

  • Automatic Shut off in the event of a major leak
  • Leak Detection
  • Gas Gauge
  • Child Safety

The Gas Fuse is not a very expensive device and we have seen retail prices from R300 to around R500 depending on how much you shop around. The box claims that it is approved by the Australian Gas Association, and a quick search of the AGA appliance directory confirms the approval, however, crucially the device IS NOT approved by the Liquid Petroleum Gas Safety Association of South Africa. This does not necessarily mean that the device is unsafe, only that it has not been submitted for testing by the local distribution agent. No doubt the local distributors will neglect to mention that fitting any device to your gas installation, that has not been approved by LPGSA, renders your Certificate of Compliance void.

Installation is fairly straight forward and the colour, illustrated instructions are fairly easy to follow.

On to the features of the device.

Automatic Shut off

A device that automatically shuts off the gas supply at the cylinder when you have a gas leak seems like a great idea doesn’t it? The problem is that it’s not quite as simple as that. The Gas Fuse is fitted directly to your gas cylinder, and as such the only information ‘input’ it has to determine whether there is a leak or not is the gas pressure and flow rate. The difficulty with that, is that the Gas Fuse can not tell the difference between you using an appliance, and a small gas leak somewhere on your line. It can ONLY detect big, catastrophic failures of your gas line. In fact, when we tested the Gas Fuse, we had to quite literally cut the gas line off before the ’emergency’ shut off actually closed. It’s worth pointing out as well, that the shut-off could only be triggered by a complete and very sudden failure of the gas line. If we cut through the line slowly, the gas continued to flow through right up to the point where the line was completely open before the valve actually shut. In other tests with larger appliances, or multiple appliances on the same line, we also found that the Gas Fuse would shut off the gas supply even when there was no failure of the line.

The danger in this is that the Gas Fuse gives a false sense of security in that it convinces the user that it would protect against gas leaks, when in fact it can not do that. Luckily it does state such in the instructions, but if you don’t read them all, you could very easily think that the device will shut off your gas in the event of small gas leaks.

Leak Detection

Gas Leak
Bubbles in soapy water indicating a gas leak. A leak like this showed almost no movement on the gauge after 5 minutes.

The leak detection function is a basic pressure test of the line. The idea being that you can place your gas line under normal operating pressure and then shut the valve. With the system under pressure you take note of the gauge reading and then leave the system pressurised for a period of a few minutes, then return to check the gauge again. If the system has not lost any pressure, then there are no leaks in the system. The theory is sound and we routinely use this method when checking new gas installations for leaks. The shortfall here is that the gauge used on the Gas Fuse is too vague. We pressurised a test line with the Gas Fuse in place and then deliberately caused a very small leak on one of the fittings. The leak was big enough to create small bubbles when soapy water is sprayed on the joint, but not so big that you could hear it hissing. Over a period of around 5 minutes, the gauge had not moved noticeably, which would indicate that there are no leaks, when clearly there was. We increased the size of the leak to the point where we could almost hear it and left it for another 5 minutes. After this time we did see the gauge move, but unfortunately for a device claiming to be a safety tool, this simply wouldn’t be good enough. We would need to be able to see, even a small leak, instantly, but the Gas Fuse simply isn’t accurate enough to use for leak detection.


Gas Gauge

I’m going to try very hard not to get too scientific here, but there are a few things that need to be understood in order for me to explain why the Gas Fuse does not work as a gas gauge. Firstly LPG is stored in liquid form in your gas cylinders. The cylinder is filled to about 80% of its liquid volume to leave room for expansion and a pocket of LPG vapour on top of the liquid. Your appliances require the vapour form of LPG and not the liquid – this is why your cylinders must always stand upright when being used. When the cylinder is filled and the pressure inside increases, the LPG starts to turn into a liquid when it reaches a threshold called the vapour pressure. This pressure will change with the temperature and the exact butane-to-propane ratio of the LPG being used, but for practicality we will say it’s around 550 – 600kPa at room temperature. This means that the vapour pocket in the top of your cylinder will ALWAYS be in that vapour pressure range provided there is at least some LPG still in liquid form inside your cylinder.

Now back to the Gas Fuse. Let’s remember the Gas Fuse is connected to the outside of your cylinder, and the ONLY information it has in order to ‘calculate’ how full the cylinder is, is the pressure. Unfortunately, because the vapour pressure of the gas is pretty much constant if the temperature doesn’t change, the Gas Fuse will ALWAYS tell you that the cylinder is full, right up to the point where it is virtually empty and the pressure starts to drop below the vapour pressure of 550kPa. In testing we connected the gas fuse to a full cylinder and placed the cylinder in the sun to start with. The gauge said the cylinder was full and in the green range. After moving the cylinder into the shade the cylinder was still in the green range but slightly lower. We then repeated the test with a 9kg cylinder filled with just under 4.5kg’s of LPG – so just under half full. In the sun the cylinder gave a green reading on the gauge, not very different from a completely full cylinder. However, when we moved the half full cylinder into the shade, the gauge dropped significantly, touching the red ‘refill’ zone of the gauge. For the final test we used a 9kg cylinder with only 1kg of gas in it. When placed in the sun the gauge was still in the green zone, indicating we had plenty of gas, even though we didn’t. When moved to the shade, the gauge eventually dropped into the red ‘refill’ zone.

It’s worth noting that the gas gauge feature can only be used while an appliance is running, and according to the instructions, it is better if the appliance has been running for about 10 minutes or more before taking the reading.

Child Safety

The Gas Fuse claims that it can be used as a safety device on unused cylinders. By screwing the device into an unused cylinder that still has gas in it, it will not allow gas through, should the child accidentally open the valve on the cylinder. Finally an advertised feature of this device that does actually work! If you screw the Gas Fuse into a gas cylinder and open the cylinder valve, nothing happens. The question becomes whether this isn’t a little redundant though? The same effect can be had by using a gas regulator with a piece of bent over hose, at less than half the cost of the Gas Fuse. Not only that, but surely if a child is strong enough to open your gas valve, they are strong and smart enough to unscrew the gas fuse from the cylinder?

In Conclusion…

We can not say that the Gas Fuse’s claims are false advertising, because it does do what it says on the box, BUT, and it is a very big but, it doesn’t do any of those things particularly well. Yes it will shut down automatically if your gas line is very suddenly cut or completely disconnected – in testing it also shut off when we were running multiple appliances or appliances with large gas consumption at start-up. However at the end of the day it was more an annoyance than a feature. Yes it can be used to detect leaks, but there are easier, more sensitive ways of doing that, besides which, you will smell LPG long before the Gas Fuse detects a leak on the system. Yes it can be used to gauge if your cylinders still have gas in them, but you have to take into account where your cylinder is (sun or shade), and even then the information is vague, at best. And yes the Gas Fuse can be used to make unused cylinders safer, but even if you really felt the need to, there are cheaper DIY ways of doing it.

Given the spectacular way in which the Gas Fuse failed all of our tests, we really can not see the point of this device. The idea is really good, but unfortunately they have tried to over-simplify the problem and produced a device that really serves no purpose. You also have to keep in mind the fact that it can render your Certificate of Compliance void. Let us not forget that without a valid Certificate of Compliance, your insurance will not pay out for ANY fire related claims, regardless of whether it was related to the gas installation or not.

There are just too many things on the negative side here and we really tried to find something that this device is good at, because a lot of our customers have asked about it. At the end of the day we would have to say there are better things you can spend your money on to make your gas installation safer, rather steer clear of this one… Eddlesgas certainly will.


Please note that the Gas Fuse used in our test was supplied as a consignment unit by an agent. The unit was brand new and boxed when it arrived and is the second unit of its type that Eddlesgas has tested with similar results. All tests were carried out by qualified LP Gas Practitioners under controlled conditions. Eddlesgas DOES NOT stock the Gas Fuse as it does not comply with LEGAL REQUIREMENTS of LPGSASA or SAQCC gas, and we refuse to stock any product that we would not use ourselves.

4 thoughts on “Products in Review – Gas Fuse

  1. Hi
    I have read your summary on the gas fuse, and would like clarity on one comment you have made , why would it make my installation non-complaint, if I attached a gas fuse to it ?
    The LPGSA operates under a mandate from the Department of Labour, with regards to implementing a scheme whereby only appliances which conform fully with SANS 1539 may be distributed or sold in South Africa – the Safe Appliance Scheme.
    However, an adaptor, such as the Gasfuse, is not covered under this standard, so LPGSA would not be required to approve it.


    1. Hi Paul, Thanks for your question – We actually had to go back to our SANS codes and do a lot of reading, as well as consulting with a number of installers on this device before publishing our review.

      Most of the installers we spoke to said that they would not certify any installation with the Gas Fuse installed. Their reasons were varied, but boiled down to a 3 main points:

      1. LPG installers in South Africa take full responsibility for any installation which they certify in their personal capacity, not as a representative of a company. In other words, if something happens on an installation that an installer has certified, that installer becomes PERSONALLY LIABLE, should it be found that there was anything non-compliant about that installation. The installers we spoke to were simply not willing to put their name to an installation which they were not 100% sure about.
      2. The reason they are not 100% sure about installing a gas fuse is simply because it doesn’t really fall into any clear definition under SANS 10087-1:2013. In fact we tried this ourselves by going through all the definitions in the code and could not find a category that fully covered the gas fuse. Gas Fuse’s AGA certification classifies the device as an ‘excess flow check valve’ – which is not described anywhere in SANS 10087-1 – that alone would be enough to argue it would render an installation non-compliant, but if you read AGA’s definitions of an ‘excess flow check valve’, the closest definition in our SANS code would classify the gas fuse as a Regulator – which is obviously not correct, but like I said, it’s the closest definition under our code. Under the Safe Appliance Scheme regulators MUST conform to SANS 1539 and although I am sure the gas fuse would, unfortunately it has not been tested nor certified by the Safety Association.
      3. As mentioned, although appliances have to conform to SANS 1539, installations must conform to SANS 10087-1 (for domestic installations), which makes no provision for this type of device, especially when you look at section 5.4 which describes how a cylinder may be connected to the rest of an installation and notice that at no point does the code allow for any other devices, fittings or adaptors to be placed between the cylinder and regulator.

      Having said all of that, we did not verify with LPGSASA whether they would accept an installation with the Gas Fuse fitted as being compliant, but having gotten opinions from the installers who actually issue Certificates Of Compliance, and reading all the related sections of SANS 10087-1, we also felt that the device would most likely render a gas installation non-compliant.

  2. OK with this said.
    What can I use to see the level of the content of LPG?
    In our business its difficult to controlee LPG changes as we have a Left and right bank and not just one person that changes these banks.
    Problem is that so many times I have found that the cylinders was changed but on delivery they could not inform me witch cylinders are full and witch are empty accept for an estimated weight difference. and if found they will not tell you that the cylinders are not completely empty.
    What product would you suggest to use? I need one on each Cylinder

    1. Hi Tinus, Thanks for the question.

      Unfortunately we have seen many gadgets that claim to be able to tell you how much gas is left in your cylinder, but at the end of the day there is only one reliable way of telling how much is ACTUALLY in there. It’s the same way we measure how much gas is left in the cylinder, and it’s very precise, if not quite as practical as having a nice gauge that tells you. The only way to accurately know how much gas is left in a cylinder is weighing it. Each LPG cylinder has it’s empty weight either printed or stamped somewhere on the cylinder. The idea being that when you weigh the cylinder, you subtract the weight of the cylinder itself and it tells you exactly how much gas is in there. As I mentioned, this is the method we use to fill the cylinders, and it is pretty accurate.

      There are lots of ways that can give you a rough idea, such as giving the cylinder a quick shake and feeling the gas slosh around inside the cylinder, but this only gives a very vague indication of the gas level. There are also magnetic strips that can be stuck onto the side of the cylinders that change colour as temperatures drop, So this would give you an idea of the liquid level inside the cylinder, but these gauges only work if the draw on that cylinder is high enough to cause rapid vapourisation inside the cylinder, and even then, are a best guess estimate.

      With a 3-on-3-off manifold as you are describing for your business, it can be tricky to control your gas usage. Assuming that you are using a vapour manifold and not a liquid manifold, each bank should balance out since there are no non-return valves in the system. So the moment you open 3 cylinders on one bank, their pressures will equalize through the manifold and they should all get used at the same rate. This means it is fairly safe to say that when one cylinder runs out on the bank, that entire side should be empty, at which point you would obviously switch over to the other bank. If you suspect that you are sending half-full cylinders back to your gas supplier, contact them and ask them to check! We frequently do this for business customers to ensure they get the best use out of their cylinders.

      Finally, the sad truth of the matter is that we can not always trust the people we work with. It is an absolutely unavoidable truth of our industry that theft is a massive problem. One of the most common ‘schemes’ is where someone on the inside actually closes the valve on one of the cylinders on the manifold, meaning in your case, you would only be running on 2 cylinders. When the gas on that bank “runs out” the gas supplier would supply 3 new cylinders and collect three empties, however one of the “empties” probably has the majority of its gas still in it. The delivery crew then sell that gas elsewhere, and they all split the profits, and since the drivers return to the depot with the correct number of cylinders, all now empty of course, it is very difficult to catch them in the act. This is why it is extremely important to have a reputable gas supplier you can trust. All our trucks have tracking devices fitted and we frequently go to customer’s sites and randomly mark their cylinders to ensure they all come back when they are supposed to. It may also be worth your while marking your own cylinders from time to time and checking with your gas supplier to make sure that the marked cylinders reached their yard at the end of the day.

      Hope this helps answer your question, and please feel free to contact us, should you need anything else.

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