monique.hubrechtsgm Posted July 2, 2017 Share Posted July 2, 2017 My dual control turnes from green to red to the other bottle the so called reserve when their is still 3.1 kg gas in at afther weighing the bottle.The same occurs on the reserve bottle on the end of the cycle.. leaving me whit 6.2 kg propane unused which is 6.2x230 liter of propane gas left in the bottle and can not be sucked out of the bottlle. So when a post in two bottles at the station they get about two third of one bottle gas back for free. Anty tips welcome to get the gas out paid for. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted July 2, 2017 Share Posted July 2, 2017 I don't see this as a problem relating to BP Gas Light containers, but to your changeover device. I don't think this is normal behaviour with a Truma Duo Control device, so you really need to ask Truma for advice. Link to comment Share on other sites More sharing options...
mildi Posted July 3, 2017 Share Posted July 3, 2017 Fit Gaslow and never change another bottle. Link to comment Share on other sites More sharing options...
Brian Kirby Posted July 3, 2017 Share Posted July 3, 2017 Derek Uzzell - 2017-07-02 9:07 PM I don't see this as a problem relating to BP Gas Light containers, but to your changeover device. I don't think this is normal behaviour with a Truma Duo Control device, so you really need to ask Truma for advice. I agree. Not sure if Monique will have a Truma Duo Control, but the automatic changeover is driven by the drop in pressure as one cylinder nears empty. If Monique turns off the gas at the full cylinder, and then sets the changeover valve to use only the near empty cylinder, making sure the gas cock on that cylinder is fully opened, and no gas is delivered, I would suspect that the auto changeover valve itself is defective. This could be further tested by taking out the near empty cylinder and cracking open the cylinder cock. If a healthy blast of gas results QED? Just do this outdoors away from sources if ignition, and don't smoke! :-D Link to comment Share on other sites More sharing options...
Robbo Posted July 3, 2017 Share Posted July 3, 2017 Agree with Brian's thoughts and his proposed testing regime. The apparent loss in pressure may be due to oily substances finding their way to the changeover valve and causing a restriction with resultant lowering of pressure. More likely if the changeover valve is lower than the outlet from the cylinders. Link to comment Share on other sites More sharing options...
keninpalamos Posted July 3, 2017 Share Posted July 3, 2017 I have this system on my old-ish Hymer i think I fitted it back in 2004-5 as it was on my previous Hymer and i quite liked it. but in recent years I have one bottle turned off so I know when I need to refill it or exchange it. Exchange being Repsol in Spain..I got caught once or twice having to empty bottles. I take it you have tried turning one bottle off to see if the other bottle will empty. I have noticed that on mine it pays to have the bottle valves open by a good 3 full turns especially if the heating and say the oven is on. Just one further thought, on my system there are 2 sub regulators, one for each bottle and the main regulator its the two sub regulators that determine which bottle is closed or open by a small pressure differential, so if you are having to hand over the two bottles with an equal amount left in them Id say it is your main regulator that has a problem and i bet its partially blocked as I seem to remember this being reported on an LPG item and it was a known Truma reg. problem all some time ago admittedly. Hope that helps or Im in trouble (lol) (lol) Link to comment Share on other sites More sharing options...
Derek Uzzell Posted July 3, 2017 Share Posted July 3, 2017 Ken What you have described is Truma's "Triomatic" system that was superseded quite a few years ago. I'm guessing that Monique's Burstner has a DuoComfort or DuoControl changeover device. Link to comment Share on other sites More sharing options...
monique.hubrechtsgm Posted July 3, 2017 Author Share Posted July 3, 2017 Impresive to read what i am talking about. Ihave a toptron dual control and crash safety shutt- off device. That device allows me to drive whit two bottles open cocks. The safety shut offs to some gravity forces like impact or a big slope. Unable to read the parametres when that will happen. Also unable to find out at what pressure the change over valve be comes active the so called set- over pressure. For sure never a empty bottle. BP light is also represented in the uk. What is the pressure full and almost empty for 10 kg propane? Link to comment Share on other sites More sharing options...
Derek Uzzell Posted July 4, 2017 Share Posted July 4, 2017 I mentioned the Toptron system in this 2015 forum discussion, but I’ve no hands-on experience of it. http://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Driving-with-the-gas-on/37348/ In principle, a changeover device should only switch from Bottle A to Bottle B when Bottle A is virtually empty and the pressure in it has dropped dramatically - and this should be true if the bottles are steel, aluminium or (like the Gas Light container) composite material. The following link http://www.toptron.de/cpu/cpu.html suggests that a conventional regulator and changeover device ‘sits on top’ of the Toptron sensor. So if Monique’s system is switching from Bottle A to Bottle B when Bottle A still has 3kg of gas in it, the likelihood is that the changeover device is to blame. A 10kg gas-bottle with 3kg of propane in it should exhibit the same vapour-pressure value as when the bottle contains 10kg of LPG, and only when the bottle is approaching empty should that pressure-value reduce significantly. Like so many problem-related queries, what is not said is whether the problem has been present long-term (in Monique’s case, ever since she bought her Burstner) or has begun to occur more recently - but either way, the changeover device should not be leaving 3kg of LPG in the bottle. As the Toptron system is rare in the UK, I would have thought that a Belgian Burstner motorhome dealership would be the best source of advice. Link to comment Share on other sites More sharing options...
Brian Kirby Posted July 4, 2017 Share Posted July 4, 2017 I seem to remember reading that the gas pressure of LPG remains more or less constant for so long as there is liquefied gas in the cylinder. Once the liquid level falls to near zero the remaining liquid converts to gas, and only at that point does the pressure fall significantly as the remaining gas is consumed. This seems logical, as the means of liquefying the gas is to pressurise it. It is also the reason that pressure gauges are a poor indicator of cylinder content. Once all the liquid has gassed off the pressure tends to fall off a cliff, giving insufficient notice to be useful in practical terms. This all points to Monique's changeover valve responding to vary small variations in pressure between the new and unused cylinder and the cylinder in use. I'm assuming that both Monique's cylinders contain propane, and that the problem experienced was not during cold weather, when the rate at which butane gases off becomes sluggish, and the temperature drop associated with gassing might push the remaining liquid below its natural boiling point. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted July 5, 2017 Share Posted July 5, 2017 As far as I’m aware “Gas Light” bottles have been marketed with the LPG inside them always being propane, and Monique refers to “propane” in her original posting. I believe the largest capacity “Gas Light” bottle contains 10kg of gas, meaning that Monique’s changeover device operates when some 30% of that gas remains in the bottle. There must be a pressure threshold below which bottle-changeover should take place, and this would need to allow for weather-temperature-related pressure variations, but bottle-switching at such an early stage cannot be correct. The type of changeover device shown in the Toptron link in my last posting is (for obvious reasons) gas-specific, so there’s a propane version and a butane version (for domestic usage). Consequently, there would appear to be protential problems opting for user-refillable bottles (as was suggested earlier) as ‘autogas’ abroad can have a high butane content and the lower vaporisation pressure might well conflict with a propane-specific changeover device’s switch-over parameters. If there’s something wrong with the regulator (as Robbo suggested earlier) reduced pressure should (probably) be apparent from the gas appliances failing to operate at maximum output. If that’s not evident, then the changeover device is the prime suspect. Link to comment Share on other sites More sharing options...
StuartO Posted July 5, 2017 Share Posted July 5, 2017 Brian Kirby - 2017-07-04 6:11 PMI seem to remember reading that the gas pressure of LPG remains more or less constant for so long as there is liquefied gas in the cylinder. Once the liquid level falls to near zero the remaining liquid converts to gas, and only at that point does the pressure fall significantly as the remaining gas is consumed..... That's my schoolboy physics understanding too - in which case, assuming the regulator detects a drop in pressure to trigger changeover, a regulator fault cannot explain the OP's experience of always wasting a third of a bottle. Could it be a drop in flow rate which triggers the changeover? Or is there some feature of the bottle's design which causes a drop in pressure as the level drops below a third? Link to comment Share on other sites More sharing options...
Derek Uzzell Posted July 5, 2017 Share Posted July 5, 2017 At temperatures above 10 degrees Centigrade the vaporisation-pressure in a gas-bottle containing 100% propane LPG will be over 8bar http://www.engineeringtoolbox.com/propane-vapor-pressure-d_1020.html and this pressure will then be reduced right down to 30mbar by the regulator. So something very odd would need to occur with the gas-bottle (whatever its construction) to affect the 30mbar pressure that should be ‘downstream’ of the regulator and ‘upstream’ of the changeover device. It’s the changeover device that detects the pressure-drop, not the regulator. Also don’t forget that Monique has said that the same thing happens with the reserve bottle. As Monique apparently has a touching faith in the expertise of motorhome dealers, the commonsense thing to do would be to seek advice from the Belgian dealership that services her Burstner and, if necessary, ask them to test the motorhome’s gas system. Link to comment Share on other sites More sharing options...
Brian Kirby Posted July 5, 2017 Share Posted July 5, 2017 Seems the best place to start. If the changeover valve is faulty (which seems to me the most probable explanation), it should be straightforward to change. Not much point speculating further until the valve is eliminated from the possible causes. Link to comment Share on other sites More sharing options...
monique.hubrechtsgm Posted July 5, 2017 Author Share Posted July 5, 2017 BP light composite are availble in 10 kg .7.5 and 5. A 7.5 will fit the hose lenght in my gas locker. There we go in our impressive gas school. The bottle itself has a design pressure of 30 bars which is indicated on the bottle. However your upstream will be 16 bars max at the pressure regulator in let. That being said that your fill pressure of the bottle or a cylinder as often used in in i the uk, but not a gas tank of 20 kg. They are filled to max 80 percent in weight. Very critical. So fill pressure is lower than 16 in the container. Once you start to regulate this pressure to your house equipment you have a Joule - thompson temp drop which can freese your gas supply. Only heating helps. Feel the difference in temp of gas phase and liquid in your container. The truma dual control CS i find out goes to the other bottle at a sensing pressure of 0.6 bars. I think the toptron will be the same. Not an idea what this means in remaining gas untill you do a weight check detucting the tarra of your bottle. The gas liquid phase of the bp light bottle is visible from the the out side in some wobble.The crash unit who shut-off the gas in the locker area is a way to heat while driving but that is another matter. There are two ways that your change-over valve can reactts before the set pressure of 0.6 bars remaining gas in the left bottle and that is sencing a leak upstream causing your excess flow valves to shut off the gas. And of a dirt stop in the inlet regulator. In that case use the bottle for barbecue you can use it untill the flame goes out. And not of a drop of gas left. Link to comment Share on other sites More sharing options...
Agaric Posted July 5, 2017 Share Posted July 5, 2017 If I'm reading the OP's post correctly about when the bottles are refilled they get back the gas that is left for free, the filling system does not allow that. On my dual control I only have one bottle open at a time as it takes nearly a month to empty one bottle and can tell from the pong on the hob when it's getting close to empty. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted July 6, 2017 Share Posted July 6, 2017 Brian Kirby - 2017-07-05 5:14 PM Seems the best place to start. If the changeover valve is faulty (which seems to me the most probable explanation), it should be straightforward to change. Not much point speculating further until the valve is eliminated from the possible causes. Replacing the changeover device may not be straightforward. The attached photo (copied from the Toptron website) shows a Cavagna regulator ‘upstream’ of the Toptron crash/tilt electrical gas-shut-off valve and ‘downstream’ of a traditional automatic changeover device that connects to two gas containers. The regulator and changeover device were both available well over 10 years ago and the Toptron system may well have evolved since then. Having remembered that Rapido has fitted this type of system to certain models, I checked my motorhome’s User Manual and found that it contained a 2-page related section. The Manual does not provide the system manufacturer’s name (possibly “Favex”) but the arrangement shown differs significantly from the attached photo and is closer in principle to Truma’s DuoControl CS product, where the changeover device and regulator are integrated into a single unit. The Truma CS system has a non-electrical crash-sensor whereas the Rapido-fitted system has a separate electronic ‘black box’ that identifies impact/tilt and activates the electrical gas-shut-off valve that’s between the integrated changeover device/regulator and the gas-bottles. The Rapido system also has various LEDs to indicate faults or which bottle gas is being drawn from. (Feedback and photos from Monique relating to her Burstner’s Toptron system would be helpful.) The Rapido User Manual drawings also show specialised gas-hoses (‘pigtails’) with a “safety button” where they connect to the gas-bottle. Presumably those pigtails provide anti-rupture protection similar to the pigtails used with Truma’s CS and SecuMotion regulators. Assuming that Monique’s Burstner has a similar set-up to that shown in my Rapido’s Manual, I can’t see excess-flow valves on the pigtails being involved with the problem she has asked about. The pressure in the gas-bottles will still be high when 3kg of gas is left in them and the excess-flow valve is there to guard against a major leak resulting from the pigtail becoming damaged. Only a major gas leakage between the gas-bottle and changeover device would cause the excess-flow valve to close and (as Monique has said) the phenomenon occurs with both bottles which (if the excess-flow valve were a factor) would imply both pigtails contributing to the problem. The Rapido Manual specifically refers to Bottle A being “empty” when change-over to Bottle B takes place, which is what one should logically expect to be the case. Monique says that Truma automatic changeover devices switch when the vaporisation pressure in the bottle drops to 0.6bar and guesses that the Toptron system should do likewise. The ‘normal’ pressure in a propane the bottle should be far higher, with a 0.6bar pressure indicating that the bottle is near as dammit empty. I’ve no idea if a “dirt stop in the inlet regulator” would cause a Toptrop system to switch gas-bottles when a gas-bottle is nowhere near empty, but it really boils back to there being a fault with her Burstner’s Toptron system (not the gas-bottles) and how easy, or cheaply, this would be to rectify would depend on that system’s specification and what is actually wrong. Monique’s last sentence suggesting what one might do if gas remains in a bottle - "In that case use the bottle for barbecue you can use it untill the flame goes out. And not of a drop of gas left” is just stating the bleeding obvious and does not address the peculiar behaviour of her Burstner’s Toptron system. Link to comment Share on other sites More sharing options...
monique.hubrechtsgm Posted July 6, 2017 Author Share Posted July 6, 2017 Yes derek the system looks like that. At start- up whit two bottles both sectors should be checked being green by turning the knob in both directions. Than choose one service bottle, the other can be left-open for stand-by. or valve closed or taken away The stand- by bottle will give gas when the service bottle has turned to red on the display knob. In the toptron manual is written a service range for the bottle of 0.3- 16 bars. At that the regulotor must be able to deliver max 1.5 kg/h gas at 30mbar to the system The change over i assume is this .3 bar min , or 300mbar. Next week i have a service check at the dealer. Link to comment Share on other sites More sharing options...
monique.hubrechtsgm Posted July 6, 2017 Author Share Posted July 6, 2017 My partner said that the reservebottle valve was closed. so the info on that was not correct. An early cut out of that bottlle is not proved yet.. Sorry to mislead. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted July 6, 2017 Share Posted July 6, 2017 I believe you’ve answered your original question by quoting from the Toptron manual the bottle ‘service range’ of 0.3bar to 16bar and assuming that bottle change-over should occur when the vaporisation pressure drops to 0.3bar (ie. when the bottle is virtually empty of gas). The changeover device seems to be a Cavagna product (There is likely to be a maker’s name on yours) and its on-line asking-price is around 65€ to 75€. Some references to the Cavagna device state that it is suitable for propane or butane gas, which is believable as a 0.3bar changeover pressure should still be OK if butane were being used within a domestic environment. It doesn’t really matter about the reserve bottle as, if the changeover device is trying to switch over from the service bottle to the reserve bottle when 3kg of gas remains in the service bottle, there’s plainly something wrong. Link to comment Share on other sites More sharing options...
monique.hubrechtsgm Posted July 6, 2017 Author Share Posted July 6, 2017 sorry for the row. This is what toptron said, translation from me of their german original leaflet: Funktion and behavior of the change-over valve. After checking that you have green on two bottles. The following can occur. In case you have red on the selector means that your service bottle gas is consumed, i repeat consumed. In that case the reserve bottle should deliver gas.In case you have red but the service bottle is not yet fully consumed, the reason can be the high pressure tube leak rupture device of the service bottle or a blockage in the tube to the regulator, for example dirt particles. That is all. The last one seems logical. About the first about the rupture in the tubes who triggers the excess flow shut-off valves on the hp side and the tubes it self including connections are about six by toptron depending on country and motorhome brand Link to comment Share on other sites More sharing options...
monique.hubrechtsgm Posted July 6, 2017 Author Share Posted July 6, 2017 Yes derek fully agreed. Or that selector knob is the mistery which is very confusing in the dark. I do not know who makes what . I have two equipment manuals dellivered about this a blue one cavagna group LPG and natural gas regulators division and toptronGmbh in Menden Germany. I wiil source this out to the bottom thanks to you. Link to comment Share on other sites More sharing options...
monique.hubrechtsgm Posted July 6, 2017 Author Share Posted July 6, 2017 Here it comes. The selector has a small rib in white on a white body indicating the service body at nine or three o clock or vice versa . They turn very smoothly. If you have it in a intermediate position this problem can occurs. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted July 7, 2017 Share Posted July 7, 2017 The changeover-device in the photo in my posting of 6 July 2017 8:10 AM above is almost certainly a Cavagna product https://www.jumia.ci/cavagna-inverseur-gaz-multicolore-277941.html though there are other makes (eg. Gazinox) that look similar and operate in the same manner. I can believe that a problem with the gas-hose connecting the changeover-device to the gas-bottle could cause the device to switch bottles too soon. Swapping the hose that currently connects the changeover device to the reserve-bottle on to the service-bottle could check this. I don’t see how a blockage in the ‘tube’ connecting the regulator to the changeover device would cause premature bottle-switching as, although this would affect correct operation of the regulator, it should not alter the pressure in the gas-bottle. And it’s the reduction in the pressure in the gas-bottle that initiates the bottle-switching procedure. The ‘rib’ on the changeover-device’s white plastic bottle-selector is visible in the photo on my posting. The rib should ‘aim' at one or other of the device’s two inlets and (as you’ve said) should be at either the 9-o’clock or 3-o’clock position. The rib should NOT be at the 6-o’clock position shown in the photo. If the rib were at any other position than 9-o’clock or 3-o’clock, there is every chance that this would affect bottle-switching. If you are saying that the rib on your changeover-device was simply in the wrong position, you’ve solved the problem. Link to comment Share on other sites More sharing options...
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