How many lbs of pressure is there when a double line pressure tank is in use?

[outboardnut]

How many lbs of pressure is there when a double line pressure tank is in use?

[frankr]

Somewhere around 4 psi.

[jeff-register]

With a sealed system here in Arizona summer I would bet up to 15 pounds. Frank, What pressure does the relief valve let go? I always filled the tank out of the boat on shore.
Jeff

[Mumbles]

A few years ago I tried several different motors to see what kind of pressure they developed in the tank and they varied slightly but around 4 PSI was the norm. I believe the pressure relief valve in the tank blows off around 11 – 13 PSI.

[frankr]

What a cool tank pressure gauge! You patent it yet?

Jeff, they can build up pressure from the sun here also. I’ve seen lots of relief valves fail to hold sufficient pressure, but never seen one fail to blow off excess pressure. Not that I’m aware of anyway. Boom ????? Good reason to junk rusted tanks.

[vintin]

outboardnut wrote:

How many lbs of pressure is there when a double line pressure tank is in use?

When in use the pressure supplied by the outboard motor will determine tank pressure, even if the tank is in the sun. The motor would have to draw a very small of fuel for a tank to build up pressure in the sun with the motor running. I don’t see it happening. If the tank is hooked to a motor that isn’t running I’d expect the float and needle valve would be over come by pressure well below 15 psi, but I don’t know what pressure. If a tank is sitting in the sun and not hooked to a motor that is when I’d expect to see the highest sun generated pressure. Just rambling as I have never used a pressure tank.

• This reply was modified 4 years, 9 months ago by vintin.

[kerry]

I just made it a habit to crack the cap when I shut the motor off. Remembering to tighten it when taking off was sometimes an issue… darn crs…

If you have too many, AND not enough, you're a collector.

[labrador-guy]

Ya darn CRS for sure! I left the gas line hooked to the motor one time. Had a hour and a half drive home. Needless to say that old tank kept pumping gas right past the needle valve in and out of the boat. Had a real mess when I got home. Sun shining and the can being shaken by bumps in the road it’s a wonder that the pop of valve didn’t open. Gas sure ran out the carb though! A lit ciggie butt and I would have looked like a jet going down the road.

live and learn
dale

[Mumbles]

Frank says: What a cool tank pressure gauge! You patent it yet?

The 10 PSI gauge is an old school Stewart-Warner unit I found at a garage sale. It came in its original cardboard box and I believe it to be NOS. The gas cap was modified to accept a fitting and it also works great for draining the tank.

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