Re: cross connections fire depts.
Fire trucks are also used to draught water in an urban environment. Meaning that one method is to hook up a hard suction like the suction for a mud pump. Engage the pump and prime. If you hook up the truck in this manner to the 5" steamer connection (the big one). Example the hydrant is connected to to a 6," 50 year old main. The truck can easily run in a vacuum and have to literally suck the water out of the water main. That is why a vacuum breaker is required on all HWH installations. Does anyone do that hell no. Most of the the building inspectors don't even know what one is when they do see one. Ever see a flattened out water heater, this theoretically can happen. Modern pumper trucks can pump up to 2500 GPM. The fireman in the cities of America usually don't have these problems. But the small unpaid fireman in the rest of the small towns and villages across the nation encounter this problem on a regular basis. Example 1500 gpm pumper connected to a 50 year old 4" ductile iron main= about a 2" main. Hook truck up 50 psi static pressure start to pump truck with (3) 1 3/4" hand lines open at 200 gpm= 600 gpm pump and main is now in a vacuum. Some one opens a hand valve to fill their steam boiler what ends up in the main. What if someone one throws the hose in the pool to fill it and opens it. What if some DIY is using a blow bag in his stopped up main sewer. Cross connection. It should be code too have at least a Watts 7 series dual check and expansion tank on the main water service. We have been doing it that way for years dual check and x tank. Where I live the village has been updating meters and have installed meter horns with dual checks when the new meter is installed. The X tank is now not an option, we get calls that my HWH is blowing the relief valve after the water deptartment has installed their new meter.
Last edited by Chauncey; 12-18-2008 at 08:12 AM.
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