We’ve been camping with motorhomes and the odd caravan since the late 60’s and always used gas for cooking and running the fridge. Initially we started with Camping Gas and learnt quickly that Butane stops evaporating when its temperature drops. If one uses a small butane bottle to run a big gas appliance then the bottle temperature drops quite quickly and with it the flame size. Like many people we changed over to Propane which keeps evaporating even if the bottle is caked in thick ice.
Our gas bottle locker like many motorhomes holds two 6 killogramme propane bottles, we have never (yet) been away long enough to empty two full bottles, probably because we normally escape during the summer to warmer climbs so items like space heating are rarely used. When taking off for the ferry port its normal for us to have one bottle with an unknown amount plus a full unused one in the locker and another full one (just in case) stored below a bed! That’s three bottles that weigh 25.5 Kg plus up to 18 Kg of gas if they are all full.
Now, having more time to roam since retirement the boss (Janet) and I have been out and about to the odd show in January. Believe me that space heating really works but does it use the gas!. We even replaced an empty bottle on a show site (at significantly enhanced cost) while we were away, just to be sure we didn’t run out or get cold. Also around the Mediterranean the authorities are tightening up on the “no charcoal barbecue’s” rule and making the camp operators pay if campers digress. So the gas griddle or BBQ will be used more. With this increased usage the mind wonders about bulk gas tanks. What are the advantages and disadvantages, or the costs? Research in several places including the Internet keeps coming up with a “Richard” at MTH, the bloke who knows so it seems. (www.mthautogas.co.uk) It’s not difficult to find where Richard operates from but a tad more difficult to actually get hold of him. Richard is a “Hands ON” person. But I managed.
I had a long initial chat with Richard for information and he was quite free with it, even to the extent of where he gets his gas tanks from. The manufacturers offer a massive range of shapes & sizes to their distributors.
These distributors must order tanks in bulk, a couple of pallet loads minimum to make it worth while setting up the automated cutting, forming and welding equipment. Most LPG tanks are manufactured for the motor industry to power engines. In this application the outlet from the tank is routed to the bottom of the tank so that liquid comes out. This is because engines consume LPG at such a rate that the cooling caused when the liquid evaporates into gas would be just so severe that fuel starvation would take place. So in engine applications the LPG is routed to an external evaporator which is warmed by the engine cooling system. Tanks with liquid take off are painted BLACK.
For motorhome cooking and heating equipment we cannot and must not use tanks with liquid take off. Special variants of these “four hole” tanks are made with the take off at the top of the tank so that VAPOUR comes out, not liquid. Tanks with vapour take off are painted an RED. The 4 holes are used for (1) Filler, (2) Gas outlet, (3) Pressure release valve, (4) Fuel level Gauge.
Several special features are incorporated into the tanks and associated plumbing for vapour take off systems. One must allow sufficient expansion space within the tank and as such tanks must not be filled in excess of 80% capacity.
A few years back this was achieved by using an “ullage valve” Simply, this was a very small manual valve positioned at the 80% level of the tank. When the tank was being filled this valve was cracked open releasing gas to atmosphere. When liquid started to come out you stopped filling the tank and closed the ullage valve.
Today things are a little more refined. Inside the tank and incorporated into the filling input is a float valve, when the tank gets to 80% full the filling automatically stops. No wasted gas! Many tank sizes require many different filling input fittings with different floats. These filling fittings include a non return valve so that LPG cannot escape back from the tank. This is reassuring because in most applications a length of high pressure flexible hose, 1 to 1.5 metres long couples this filling input to the bayonet fitting situated on the outside of the motorhome. Should this external bayonete fitting become damaged the only gas that could escape is that within the hose.
Properly constructed tanks also include shields to ensure that turbulence in the tank during filling or vehicle movement does not result in liquid gas being sent into the outlet.
Mounted directly to the tank will be a manual shut off valve to which is directly fitted a regulator to bring the pressure down to that suitable for our motorhome appliances.
The tank also includes a level indicator behind a robust clear window. To simplify keeping one eye on the LPG level a remote LED indicator can be provided which fits inside the motorhome. The tank end of this remote system is a replacement fuel gauge which monitors the position of the pointer on the actual tank gauge magnetically and also provides an electrical output signal for the remote LED display.. All of this equipment on the side of the tank is protected by a stout cast aluminium enclosure.
Having selected my ideal tank from the manufacturers web site I then emailed the distributor who were very friendly but pointed out the necessity for bulk orders. I tried several sizes without success.
Eventually we phoned Richard again who suggested we took our motorhome down to see him for some guidance.
Two hours later we are deep in the beautiful Forest of Dean at Parkend near Lydney. Having left Basingstoke the rain has stopped and even some sun was shining. Only a few cottages gave away its previous existence as a mining area. MTH Autogas has been re-located in a comprehensive and expansive workshop facility previously used as the Forestry Commission vehicle workshops since July 2004. The only outward signs of its existence were the signs for the Forest Vehicles Workshop. Knowing MTH’s post code and use of www.Multimap.com was a great help in finding the location. This workshop came with a rolling road and has Krypton tuning equipment. The workshops have huge tall doors and can accept up to 9 coach built motorhomes inside. Work has already started on a reception area and facilities in work include a shower and a disabled toilet. There is much land around the workshop and it is planned that up to 5 motorhomes could stay overnight while work was ongoing.
Richard Cecil is now assisted by Tony Evans who looks after the admin, not Richards favourite aspect of business!. A few phone calls and some brain storming come up with a result, a 55 litre tank that is available, will fit in the available space, and one that DHL should get from the European distributor in 4 working days. Tank weight is 27.7 kg, only a couple of kilos heavier than my three 6Kg bottles! A price was agreed for a complete DIY KIT.
This 55 litre tank at 80% full will hold 44 litres of LPG. The density of LPG at 15-20 °C is 505 kg/m3 so this makes 22.2 Kg of liquid Gas. Nearly equivalent to 4 X 6 Kg bottles.
Back home and some preparatory work needed to be done. The tank ordered was thinner and longer than my non available “ideal” chosen from the tank manufacturer’s web site. My initial plan was to fit a tank between two chassis outriggers. The revised plan is to fit a longer smaller diameter tank beneath these outriggers. The regulations require that a minimum of 9 inches clearance remain between the lowest point of the tank and the ground. The final installation should have significantly more clearance than this.
Several year ago I replaced the thin flexible kitchen sink waste pipe with something larger to stop the boss complaining about the time the sink takes to empty. I needed to slightly re-route this waste pipe so that it ran within the depth of the chassis outriggers. A visit to Jewsons for a couple of elbows and a bend and a morning’s work saw this job completed. . Two angle brackets were also made (from an old bed frame) and pre-painted which would bolt onto the two existing stout chassis outriggers with M8 bolts after drilling two holes in each.. These angle brackets will form the pick up points for the cradle which will accept the tank.
The tank comes with all the direct high pressure fittings already in place. The “kit” includes the tank itself, the support cradle, straps and mounting hardware, The high pressure filling hose , a length of 8mm copper pipe, Filling adaptor and housing, Regulator, Replacement tank gauge with electrical output and the remote fuel level display to mount inside the motorhome .
The next job now is to position the cradle under the motorhome, hold it in place with a couple of clamps and check clearances with a cardboard template of the diameter of the tank. Its now safe to mark the two angle brackets for drilling. As luck would have it the spacing of the mounting holes provided in the cradle was nearly perfect for the spacing of the angle brackets under the motorhome.The angle brackets and cradle were then bolted in with high tensile M8 bolts and nylock washers. Then all parts were given an additional coat of white paint to provide additional environmental protection, Four supplied rubber buffers were fitted to the frame.
All of the external surfaces of the aluminium enclosure were given a coat of paint. Assembly the following morning and the tank was ready to fit. .
The two clamping bands were fitted to the frame with the two stepped pins provided in the kit. . The front of the camper was driven onto some stout wooden blocks to improve ground clearance and a couple of long timbers were laid under where the tank was to be fitted. These timbers were long enough to enable the tank to be placed on them alongside the van then slid under afterwards. A large ratchet strap was looped over the top of the frame and under the tank. After sliding the tank under the van the ratchet strap was used to hoist the tank into position. Wooden blocks were used to steady the tank and to support it when the ratchet strap was released and re-tightened during the lifting process. .
The last remaining item to fit is the LPG filler.
I made a paper template for the 70mm diameter hole and used this to mark the GRP sidewall of the van. I used a small electric drill and a 5mm diameter bit as a router to cut out a disk from the GRP. Finishing up with a half round file..
The outside view of the filler is black and bland and the protective cap is released by applying pressure and turning anti-clockwise.. Back view shows the fitting of the high pressure filling pipe to the coupling.
A visit to our local Autogas station and a learning experience on how to operate the equipment required help, the station staff had not enabled the pump since the last customer.
The filling procedure is to line up the slot in the end of the nozzle with the two pins on the bayonette inlet fitting on the motorhome, then turn the outer ring of the nozzle some 45 degrees locking it in position. Then fully squeeze the trigger and lock it in the squeezed position with a small catch. Then one presses and holds in a large button on the pump. Filling then commences. The filling will automatically stop when the 80% valve closes off the inlet to the tank. Then release the trigger and finally turn the outer ring of the nozzle to release it from the bayonette fitting. A small amount of gas trapped at the end of the nozzle will escape when this is done, this is normal.After holding the button in for several seconds the fuel gauge which initially said empty now rose up the row of green LED’s and says full.
Interestingly commercial LPG is a mixture of Propane and Butane. In the UK it’s about 95% to 100% Propane. On the continent it alternates between 40% Propane in the summer and 60% Propane in the winter.
Clive February 2005
MTH Autogas have since stopped trading..
Peter Durrance has advised me of a company in Caernarfon.
The knowledge and assistance provided was beyond reproach.
FES do not offer a fitting service but carry massive stocks of tanks and equipment (supplying many manufacturers whom we all know very well) and are able to specify and supply everything needed for an installation down to every last fitting, hoses and accessories.
One suggestion was made that had a lot of merit. It’s very tempting to position the tank so that the main shut off tap is easily accessible under the side of the van. But should you vehicle get side swiped its vulnerable and should the brass fittings become knocked off then liquid propane will very quickly dump onto the ground. Richard suggested mounting the tank with all the fittings facing inboard. The tank is very thick steel so will take a significant knock; it’s much more robust than the brass fittings.
With this revised longer tank it was necessary to move the outside gas connector we use for the gas BBQ further along the skirting. Fortunately the copper pipe was long enough so three more holes and a new lick of paint re-locates this connector. However this did leave one large and two small unwanted holes in the skirting. The area around these holes was thoroughly cleaned and the edges of the holes freshened up with a file. Several overlapping strips of cellotape were stretched across the holes on the outside. These followed the contour of the fibreglass skirt quite well. A fibreglass repair kit was used to back fill these holes quite generously and overlapping on the inside. The front could be seen through the clear tape so it was easy to ensure no air bubbles were trapped. When the resin had cured the tape was removed leaving a near perfect external shape and finish. After a small amount of work with wet and dry the area was masked off locally and painted to match the skirting. (Dulux white gloss house paint matched quite well) .
Attention now turns to the tank. Removing the central knob allows the cover over the tank fittings to be removed. After removing two small screws the plastic fuel gauge is lifted out and replaced with that supplied separately in the kit, this having a pair of wires hanging out of it. It’s important that this gauge is mounted the right way up, it’s straight forward. The tank has arrows denoting TOP and the text on the gauge needs to be right way up. The test is to position the tank in its normal mounting position (with the plate with all the fittings at 105 degrees) and the gauge should indicate empty. As you roll the tank the gauge will move away from empty! .
The cover over the brass fittings includes a couple of plastic bungs each end and opening out these allows the filling hose to be fed through the enclosure to the filling fitting on the other end of the tank. This was done because all incoming and outgoing services were required at one end of the tank.. The regulator was fitted and the wires to the new tank gauge extended with some two core cable and insulated in-line spade connectors. Lastly two M4.5 holes were carefully drilled into the knob on the master gas tap. This was to permit an extension to be provided so that the master tap could be turned ON or OFF without the need to remove the cover.
The cover was carefully marked to denote the middle of the main gas tap beneath. It was then drilled 14mm. A short length of M10 bar (cut from a bolt) was drilled and a length of 4mm thin bar passed through the hole. This 4mm bar was bent to match the pitch of the holes drilled into the gas tap knob. A grommet was fitted into the enclosure lid and the M10 bar passed through it. One more hole through the 10mm bar on the outside and an M4 bolt and Nylok made the external handle..
A piece of flexible cable was used as a template to identify where the existing 8mm copper gas pipe should be cut so that it was the correct length to reach the new fitting on the new regulator. The remaining cut end going to the old gas locker was fitted with an 8mm joiner and blanking pipe. This will enable us to remove the tank and re-connect the original pipe work should we wish to at a later date.
The 2 core cable from the tank gauge was routed through a 7mm hole drilled in the floor of the van to a switch panel with two spare positions which currently accommodates the switch for the electric step. I left some 500mm of wire beneath the van looped and cable tied it in a safe place. Should I need to lower the tank for any reason I have sufficient cable length to allow this. The two spare positions in the switch panel were used for the remote tank LPG level gauge and for an additional push button switch.
I wired this push button switch in series with the supply to the gauge so the gauge consumes no precious electrical energy unless the button is pressed..
The gauge was connected in accordance with the simple instruction supplied with it. The gauge has 3 three wires, the tank sensor 2 wires.
Pump prices for LPG are around 40p per litre, that’s 80p per kilogram of gas.
At these prices a typical 6KG bottle would cost £4.80 to refill. Calor gas charge £12.60 plus another £1.50 to deliver. We have paid £15.00 at a show for an exchange bottle. So running cost works out somewhere between one third and one half that of bottled gas. There are over 1250 Autogas outlets to fill up from in the UK alone. Many on the continent where they use different filling connectors. Adaptors are available for all. These adaptors screw directly onto the front of the installed UK fitting.
Expect to pay around £350 for a DIY kit and £550 for a fully fitted system. It seems that an individual is entitled to do this type of work for themselves if they wish. More draconian rules apply if work is done for someone else. Richard also pointed out that if anybody considering a DIY kit is not 100% confident then they shouldn’t attempt it. Get it fitted professionally. Good advice!.
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