LPG Tanks

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Nereus
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LPG Tanks

Post by Nereus » Mon Jan 02, 2017 5:04 pm

I'll bet the ranch not one safety impact test has ever been performed here to determine safety of those LPG installations.
The tanks themselves are tested and approved by TISI, as per the following:

http://app.tisi.go.th/standard/comp_eng.html

The relevant section for the tanks is: Mechanical Engineering and Vehicles: TIS 370-2552 (2009) Liquefied petroleum gas cylinder for internal combustion engines, Effective Date : August 8, 2010

BUT, the problem is both the installation, and the follow up ongoing tests at the annual licencing of the vehicle.
The DLT demands the INSTALLATION be re-certified after 5 years. Having just gone through this a couple of months ago, it is a joke, to say the least. Where I had it done they more concerned with providing a photo of the car and the "licenced" operator. The actual testing consisted of spraying some detergent around under the bonnet, nothing more than a visual look of the tank.

It was inspected after it was first installed, and noted in the blue book. They also measured the distance from the back bumper to the tank, which is inside the car.

I have since fitted an inertia switch into the system, which closes the tank solenoid in the event of a crash and cuts off the gas supply.

There is more to this, I will come back to it.
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Re: LPG Tanks

Post by Nereus » Tue Jan 03, 2017 11:12 am

There is a big difference between LPG and CNG (which the Thais INSIST on calling NGV) tanks.

LPG is stored at a relatively low pressure of around 100 psi. The tanks are tested and certified to a maximum working pressure of 370 psi(22.5 bar). They are constructed from rolled metal plate and arc welded at the seams. They are fitted with a pressure relief valve, which is designed to released a small amount of gas if the tank heats up. The piping and other fittings in the system reflect the relatively low pressure, and no high pressure fittings are required.

CNG tanks are high pressure tanks, around 3,000 psi to 3,500 psi(well over 200 bar). They are required to be tested at 25% over the designed working pressure. The tank is constructed from thick alloy steels, and the rest of the installation reflects the much higher pressure involved including high pressure piping. As far as I know CNG tanks used in Thailand are imported and comply with international standards.

It should be noted that to run purely on either gas a spark ignition engine is required. To run a compression ignition(diesel) engine it either has to be converted to spark ignition, or set up to run on a mixture of gas and diesel. Most trucks that you see on the roads here with a big rack of gas tanks, use this method with is called "fumigation". About 60% gas is used (usually CNG) and the diesel is injected in a smaller amount to provide ignition, as the gas alone does not reach self ignition temperature by compression alone.

Like most things in Thailand, there are rules and regulations in place that should provide for safe and workable systems, but whether or not the rules are enforced or followed, is entirely another thing.
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Re: LPG Tanks

Post by Nereus » Sat Jan 07, 2017 4:03 pm

Here is a perfect example of how not to install gas tanks. CNG tanks can be mounted horizontally, but even then they should have a strong protective structure around the valve end. I see many trucks with the valve end just sticking out in the breeze. CNG is lighter than air, so at least any leakage will tend to disperse upwards into the air.
cng tanks.jpg
cng tanks.jpg (29.35 KiB) Viewed 1048 times
NGV truck leak panics Lampang

http://www.bangkokpost.com/news/general ... cs-lampang

LAMPANG: An NGV-powered trailer truck got stuck in a low underpass on Friday night, causing natural gas to leak from seven tanks before authorities managed to move the vehicle following a delicate six-hour operation.
The gas leak caused panic among people near the scene of the incident in Hang Chat district but no injuries or other damage resulted.

Pol Capt Rungruanchai Uppakara, deputy investigation chief at Hang Chat police station, led rescue workers to the scene after being alerted at around 10pm Friday. They found the 18-wheel vehicle with a Saraburi licence plate stuck underneath the Lampang-Chiang Mai bridge. The truck, loaded with TPI cement, was powered by NGV.
 
Seven gas cylinders installed behind the cab were jammed against the ceiling of the underpass, which was 2.5 metres high. The truck was unable to move and some gas began to leak. 

The hissing sound from the valves triggered panic among people and motorists nearby. They ran for their own safety for fear of an explosion.   

Police quickly declared the underpass off-limits. A team from the Lampang disaster prevention and mitigation office and a lighting truck were deployed to the scene, which was dark.

The team took more than six hours to extricate the truck by emptying the seven cylinders and using blowers to disperse leaked gas from the area. The front tyres of the truck were deflated to lower its height so that it could be moved.  

Driver Sattaya Pukonglee, 23, told police that he had been driving from Saraburi to deliver cement to Lamphun. When he arrived in Hang Chat, he saw another truck driven by a friend parked for repairs on the opposite site of the road.

He said he was trying to make a U-turn via the underpass so that he could buy some food for his friend.
When he drove into the underpass, his truck became stuck, he said.
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