Motorhomes


LPG gas and cyliner filling
LPG tube and hose
Propane gas verses LPG 


Technical Report - Motor Caravanner Aug/Sept 2011, Issue 292

LPG gas and cylinder filling

I have had many calls recently regarding the make up of the LPG gas that we are receiving in New Zealand now and the difficulty in getting your own cylinders filled.

I have made a few phone calls regarding this and the results are that the make up of LPG now being supplied in New Zealand is at best a mix of 60% propane and 40% butane. However be prepared to receive a 50/50 mix or worse if you are getting a swap bottle exchange. This is because New Zealand is now self-sufficient in producing its own LPG and is not importing overseas product any more. The legal minimum mix is 50% propane, 50% butane. I know there were some filling stations supplying a higher mix of propane gas because of an individual supply agreement, but at least one has been bought out by the major supplier of LPG and has done away with that supply agreement .

You will also find it more difficult to have your own cylinders refilled by a petrol station now, as many of the forecourt LPG filling facilities are being shut down and replaced by the exchange-style filling system, which will only supply the QCC valved 9Kg cylinders. This means the petrol station does not need to have trained staff on site to fill your gas cylinders any more. It also means less risk to the petrol station of having its dangerous goods licence put at risk because of an employee not filling an LPG cylinder correctly.

To have your cylinder filled you will have to locate a local cylinder filling station and support them by giving them your LPG cylinders to fill. How about getting your area committee to mention the service in your local area newsletter? If you don't support them, don't be surprised to see them disappear as well.

Remember what I have mentioned in this column before: ensure you empty your LPG cylinder completely before refilling it or you will end up with a cylinder with very high butane content. This will cause all sorts of problems with LPG appliances in your motor home.

Support your local gas cylinder testing station. Don't discard your old, often well made gas cylinder. Get it retested and it will do another 10 or 20 years for you. The closing of testing stations is becoming common around New Zealand, and this will lead to one having the knowledge to help members concerning gas cylinders and LPG.

Remember the saying: "use it or lose it!"

I hope this article helps you to get full enjoyment from the gas appliances in your motor home.

Supplied by Lex Ward #12673 LPG advisor to the New Zealand Motor Caravan Association.


Technical Report - Motorcaravanner Oct/Nov 2011, Issue 293

LPG Tube or Hose

I am often asked by members:"What should I use to run the LPG in my motor home or caravan?"

The current standard for ' LPG installation for non-propulsive purposes in caravans and boats' NZS 5428:2006 sets down prescriptive guidelines for the construction of the total LPG system for your motor home or caravan.

I strongly recommend that all persons building motor homes or caravans have a copy of this standard on hand before you even start the project. This standard can be purchased from Standards New Zealand, www.standards.co.nz.

This standard states that copper tube shall be manufactured to comply with AS 1572, with a nominal wall thickness of 1.22mm. Hose assemblies shall comply with AS/NZS 1869 Class C, or other similar standard.

When you use copper tubing, joints should be of capillary type for brazing, or should be flared or be a double-olive type compression fitting. Soft soldiered joints should not be used.

The safest and easiest connection fitting system to use with copper tube is commonly known as 'Swagelock' or Letlok' .Both of these proprietary systems are very similar and use 'Double- ferrule' or 'Double-olive compression ring systems that securely seal to the tube when a nut is tightened onto the fitting.

You can fit these fittings in very confined spaces: all you need is sufficient space to use two spanners on the fitting. They also come in various configurations, like tees, joiners, male and female pipe threaded fittings.

Another word of warning: ensure you get the correct thread fittings – BSP for English an European equipment, and NPT for American equipment, as they are different threads. Single olive type fittings are not acceptable unless they are supplied by an appliance manufacturer for the connection of that appliance in accordance with that manufacturers' instructions.

Copper tube being metallic, has a very long life when installed correctly.

Where you use flexible hose or tube, it must comply with AS 1869 Class C or other similar standard.

Garden hose unacceptable

It is also not acceptable to use a length of garden hose. The garden hose is made to pass water and will quickly fail when used with LPG. Please don't chortle at this as I have seen it used on more than one occasion.

You must use proprietary metallic hose tails. It is not acceptable to just shove the hose on to a copper tube or pipe and wrap a piece of wire around it and give a twist! If you do, it will simply slide off when things get warm- not a good look.

Hose clamps should be one piece metallic clips. Note: worm drive hose clips (also known as jubilee clips) are NOT acceptable. The reason for not using worn drive hose clips is because the worm drive can easily strip; you may think you are tightening the clip when you are not. Leaking radiator water is not as big a problem as leaking LPG.

Remember to not over-tighten the hose clip or you may damage or even cut the hose. Also do not use hose where there is heat, like around a fridge or behind a stove. The heat can cause the plastic within the hose to migrate from under the clip causing the hose to become loose and develop a leakage of gas, or worse still, get a hole melted in it, a very big leakage indeed!

Also bear in mind that hose has a finite life, say 10 years maximum. The hose by way of the manufacturing standard, must have the manufacture date printed on it. It will age over time, as the LPG will eventually leach the plasticisers out of the hose material, and make it become rigid, and thus necessary to replace the hose.

From this discussion you can see it is best practise to use copper tube where possible and hose where you require some flexibility, say from the LPG regulator to the copper tube, where you will be moving the hose to change the LPG cylinders or where it is physically impossible to fit copper tube. Some use hose where you can easily access it to make replacement easy when required.

Don't hide flexible hose away where you can't see it, or you may regret it if something does go wrong.

Where possible the runs and joints of tube should be under the vehicle, with only vertical runs going to the appliance connections inside the vehicle.

Also remember to leak test your pipe work using a soap solution with the pipe work pressurised with gas or air before lighting any appliance up.

I hope this article assists you to have many safe, uneventful journeys in your motorhome.

Supplied by Lex Ward #12373 LPG Adviser to the New Zealand Motor Caravan Association


Technical Report

Propane gas verses LPG.

As explained in the article I penned about the virtues of propane gas, printed in 218 issue of 'The Motor Caravanner', there are distinct advantages in using this product in your motor caravan gas cylinder. So following the odd query raised since the last article here goes again!!

The major advantage of using propane or propane enriched LPG, will be found during the colder months of the year. As most motor caravans stow there gas cylinders in a fibreglass locker to which a door is fitted, with very little ventilation. It will be found, that when there is reasonably prolonged use of gas appliances in the motor home, the temperature of the liquid contents of the gas cylinder will start to take a dive. If this temperature goes below about 4oC, the butane contents of the cylinder will stop vapourising and thus only permitting the removal of the propane contents of the LPG, causing butane enrichment of the LPG. Once all the propane has been used the cylinder will be unable to produce any further vapour until the contents of the cylinder warms up to about 8oC and the butane begins boiling again. A similar problem will happen if you cover your gas cylinder with a tight fitting cover to protect it from stone chips on the draw bar of your caravan.

One of the first indications of this problem happening is when you attempt to make that morning cuppa on a rather frosty morning. You light the gas cooker, that worked perfectly last night, and low and behold it only produces a rather weak orange flame that wouldn't boil anything. Yep it happened to me!!! Or worse still the fridge has turned itself off.

There are two possible methods to prevent this happening, one is to use propane enriched gas, and the other is to add external ventilation to the LPG locker, to allow air movement around the cylinder. This ventilation will help to keep the contents of the cylinder at ambient temperature. Another strong recommendation is to ensure you completely empty the contents of your LPG cylinder before refilling it, because if you just top it up you will find that what was left in the cylinder before refilling it would have been predominantly Butane which will cause you more grief and sooner!

Another possible cause of this problem is where you are using too small a size gas cylinder for the installation. You should remember there is a finite amount of gas per hour that can be drawn of a particular size cylinder, if you exceed this amount even with the best ventilation you will encounter the problem of NO gas. So when building your motor home, fit the largest sized cylinders you can and use the highest propane content gas you can get.

I hope this article helps you and makes your movanning more pleasurable.

Lex Ward #12673 of Wards RV Accessories, 25 Bristol Square, Lower Hutt, Wellington.
Ph 64-4-569-5598 Fax 64-4-566-8044 www.wards.co.nz