New 30 mbar gas regulator

[david lloyd]

Hi everyone The new motorhome had a red pigtail going from the gas locker mounted regulator to the cylinder and there was a push in valve at the cylinder end of the pigtail and similar valve on the underside of the regulator itself. At the handover I was told to open the cylinder valve and then simultaneously press in both valves on the pigtail and the regulator. They would stay open and allow gas to flow. I was also told that this was the 'new' european standard to allow the gas cylinder to be left open in transit because these one way valves are designed to shut off, preventing the flow of gas from the cylinders even though it is open, if the pigtail is damaged in an accident. I had two 11kg gaslow cylinders fitted yesterday which do not use the red pigtail and have proper high pressure hoses fitted from both cylinders to the regulator via a manual change over gauge. This removes the one way valve on the red pigtail but leaves the one on the regulator. However, with the cylinder valve open I do not need to press in the one way valve on the regulator to get gas to flow to the appliances - so that valve seems redundant now. Does anyone know what this valve is for? Did it work in conjunction with the valve on the red pigtail i.e. monitoring pressure between the two? I don't think I need worry too much about it. The cylinders were fitted by a reputable lpg installation company and the system now operates just like my previous van but it intrigues me as to what the valve/valves are for. Best regards, david

[Derek Uzzell]

What you have described is a "Drive-Safe" regulator with GSW (gas pressure switch) and a gas-hose with HRP (hose rupture protection). Both items are proprietary Truma products and don't represent a new European standard as such. It's regularly implied in leisure-vehicle publications (eg. the MMM Expert Guide "Understanding your Motorhome") that there is now a single 'Euro-standard' bulkhead-mounted regulator, but this is not the case. It's the 30mbar butane/propane gas-pressure that's the present motorhome/caravan Euro-standard and a number of companies manufacture regulators that deliver gas at 30mbar pressure. Although such regulators are normally bulkhead-mounted, gas-bottle-mounted versions are still commonplace on German-built leisure-vehicles. The objective of the Truma system fitted to your motorhome is to provide protection if a gas-fuelled heater is being used while the vehicle is being driven (historically an accepted and permitted practice in Germany) and a road accident takes place or the vehicle's gas-system develops a severe leakage. If the high-pressure hose between gas-bottle and regulator is ruptured then the HRP valve will shut off the gas flow automatically. The valve on the regulator performs a similar function if a major leak occurs on the low-pressure (30mbar) side of the motorhome's gas system. Truma claim that Drive-Safe permits gas-fuelled heaters to be used legally in moving vehicles even in countries like France that have specific regulations restricting that practice. (It's also possible that Drive-Safe anticipates that more stringent EU-wide regulations will be introduced for on-the-move vehicle gas heating.) My understanding is that, in order to 'circumvent' (say) French gas-heater-related traffic regulations, a vehicle would need to be fitted with the Drive-Safe regulator AND the HRP hose. As your Gaslow installation deletes the HRP hose then presumably this would prohibit you from legally using a gas heater (should you so wish) while driving in EU countries that have (or will have) regulations that restrict this practice. (To minimise supplementary comments, I'll just emphasise that, for maximum safety, one should NEVER drive with any gas-fuelled appliance operating in a motorhome and ALWAYS shut off the motorhome's gas supply at source before setting off.) The Drive-Safe regulator has three gas-flow output variants (0.8kg/h, 1.2kg/h or 1.5kg/h) and, to provide the protection it's designed for, needs to be matched to the motorhome's gas system. I'm a mite wary of the "simultaneously press in both valves" advice you were given at hand-over as I would have thought these were 'reset' buttons that one would only need to operate in the event of the related valve(s) being triggered (eg. if a gas-bottle were changed perhaps). As Drive-Safe is quite new I would have expected there to be instructions about it in your motorhome's handbook (just my little joke!) or a supplementary Truma leaflet. If not, then I'm certain Truma(UK) can provide you with appropriate documentation if you contact them via the www.trumauk.com website. Outside the UK "Drive-Safe" is called "SecuMotion" and you can find more details under that name on the main Truma www.truma.com website (English version available).

[david lloyd]

Many thanks for the comprehensive reply Derek - I am reassured that there is no risk attached to the slight modification by removing the HRP hose. We will never be using the gas system when in transit as we have a rear heater matrix so should be OK. Once again, many thanks, david

[Derek Uzzell]

Just to satisfy my own curiosity I'll see if I can get a technical leaflet on Drive-Safe from Truma(UK). If it turns out that there's anything odd about it that I was unaware of then I'll report back.

[Derek Uzzell]

Truma(UK) has now sent me an Installation/Operating Instructions leaflet for the SecuMotion ("Drive Safe") system. As this product is safety-related I suggest that anyone who recognises that SecuMotion is installed in their motorhome should ensure they have a copy of this leaflet. SecuMotion is a development of the current motorhome gas-supply norm, comprising a modified gas-bottle-to-regulator high-pressure hose feeding a modified bulkhead-mounted 30mbar regulator. The hose has a green 'reset' button at the gas-bottle end, while the regulator carries a green 'gas-flow monitor' button. To bring the system into operation you turn on the gas-bottle then firmly depress the hose's green reset button. You then hold down the regulator's green gas-flow monitor button for about 5 seconds, repeating this process if necessary. Presumably repetition may be needed if your motorhome's gas system is extensive or hasn't been used for some time. (As there's nothing in the Instructions leaflet to say that the buttons must be pressed simultaneously, I suspect this is a pink herring. However, as you don't need a science degree to appreciate that there is a logical sequence to the order in which the buttons must be pressed, it makes sense for a dealer to preach the Simultaneous Gospel to customers unfamiliar with SecuMotion.) Once the system is operating, the gas-hose's safety valve will shut off the gas if a major leak occurs between the bottle and regulator, while the gas-flow monitor will shut off the gas at the regulator if the pressure on the low-pressure side of the system drops to 27mbar or the flow rate through the regulator reaches 125% of the regulator's design setting. As I said previously, the objective of SecuMotion is to allow LPG-fuelled heaters to be used legally throughout Europe while a motorcaravan is being driven (Truma cite EU Directive 2001/56/EC). However, that doesn't mean you can just graft SecuMotion on to any motorhome and it suddenly becomes legally OK to whiz around Europe with your gas-heater on full blast. The first prerequisite is that the gas-heater itself be type-approved for use in a moving vehicle (eg. Truma C- and E-Series). Then all the gas burning appliances in the motorhome must be to 30mbar standard and SecuMotion must be matched to the vehicle's gas system (Truma have software called "LPG Flow" to assist motorhome manufacturers to do this). There are also 'mechanical' issues to address: gas pipework must be of a suitable diameter and, to minimise the chance of liquid LPG reaching the SecuMotion regulator during driving, the regulator must be positioned at or above the valve on the gas-bottle. (See photo bottom-left on page 12 of MMM's "Understanding Your Motorhome" guide. If the regulator shown was the SecuMotion type, its location would be acceptable for the Campingaz cylinder but too low for the adjacent Calor propane bottle.) It's a fair bet that SecuMotion will become standard fitment on German-built motorhomes but, as it adds about £30 to the overall cost (based on Truma's 2005 UK price list), questionable whether the system will be installed by motorhome converters in the UK where turning off the gas while travelling is strongly recommended and using a gas-heater en route would be viewed as near-lunacy.