Proper Placement of Liquid Petroleum/Propane Tanks- Chelan Home Inspection
In most of North Central Washington (Chelan, Douglas, Grant and Okanogan counties) it is common to find Liquid Petroleum Gas (LPG)/Propane tanks on homes. These are mainly for fireplaces in this area but may be used for BBQ’s and a few cooking appliances.
Due to the nature of LPG there are some safety requirements needed in the placement of these tanks.
Propane is heavier than air so it will tend to settle in low spots, such as crawlspaces and basements.
There are two main dangers due to it being heavier than air. One- it is a possible explosion if the mixture of LPG and air is right and if there is an ignition source. Two – LPG can pool and displace air, causing a decrease in oxygen concentration that could lead to suffocation. LPG is not toxic but suffocation is an issue. This is why the 3 or 5 foot requirement for crawlspace vent is in place.
There are two main tank type DOT (Department of transportation), this is most common, and ASME (American Society of Mechanical Engineers), these are usually the buried tanks.
For DOT cylinders (tanks)that are filled offsite a 5 foot minimum between relief valve discharge and external source of ignition (air conditioner), direct vent, or mechanical ventilation system.
If the DOT cylinder is filled on-site from a bulk truck, the filling connection and vent valve must be at least 10 feet from any external source of ignition, direct vent or mechanical ventilation system.
DOT diagram for setbacks and clearances -
The rules are that any ASMErated tank that is filled on-site must be located so that the filling connection and fixed liquid level gauge are at least 10 feet from external source of ignition (i.e. open flame, window A/C, compressor, etc.), intake to direct vented gas appliance, or intake to a mechanical ventilation system.
For tanks that are 125 water gallons or less you need to maintain five (5) feet from any opening of a house (doors and windows). If the bottom of a window is higher than 32 inches, the tank can go directly under the window.
Though this picture is poor picture the tank valve is less than 5 feet from an operable window.
ASTM diagram for setbacks and clearances -
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