3000psi vs. 3600psi

[Dugless]

Can someone please explain what the difference is. I have a Crown Vic and inside of the fuel door is a sticker that states to fill the vehicle at 3000 psi. I have the extended tanks (6 total) and I regularly fill up with the 3600 psi nozzle. Is this dangerous!

When I fill up with a 3000 psi nozzle I average about 230 miles. I get almost 300 on a 3600 fill up.

Am I harming my vehicle in any way?

[Larryect]

Re: 3000psi vs. 3600psi

I just have to say it first....

600 psi.


On a more serious note. There are people much more expert than me on this site. But, I would think that it is not a good idea to subject 3000 psi rated tanks to 3600+ psi on a regular basis. I say + because many dispensers are actually set up to give you more then the rated pressure to compensate for the "fast-fill" effect of the gas heating when being compressed.

However, You should not be able to unless someone hase changed your fuel inlet. I would try to get a visual of your tanks and see what they say on them. If any of them are 3000, I would not use 3600.

[Dugless]

Re: 3000psi vs. 3600psi

Yes, the guy I bought the car from put a 3600 nozzle on.

[CraziFuzzy]

Re: 3000psi vs. 3600psi

This was pretty common on crown vics a couple years ago, people were swapping nozzles out with 3600 nozles, and there were even shops in SoCal that would grind down the 3000# nozzle to the 3600# size for you. It is, obviously, not wise to overpressurize the tanks, especially with a fast fill (which is pretty tough on the tanks to begin with.)

That being said, I also have a 3600# nozzle on my 3000# Crown Vic, though it is because i needed a replacement nozzle, and this one I acquired for free. I have not hooked it up to a 3600# station yet though. I will be installing a home compressor at some point in the near future (hopefully, assuming finances line-up), at which time, I will be slowfilling to 3600# at home (a 3000# pump would just not be worth it with my wive's 7 gge 3600# "mini-tank" on her SUV). I will still not use a 3600# fast fill though, as I'd rather not take the risk.

[afvman]

Re: 3000psi vs. 3600psi

Dugless et all,

Not the best idea. For 70 miles difference, I'd error on the side of caution.

Now, here's the deal on pressures. (For what it's worth, the U.S. is the only country that uses 3600, everyone else is at 3000.)

Cylinders should never be pressurized to more that 125% of the service pressure, i.e., 1.25 x 3000=3750. If you ever go above this it's a Level 3 defect and the cylinder should be condemned, removed and destroyed.

But, all pressures are assumed to be at a standard temperature of 70 deg. F. So, fill stations are designed to go higher if it's above 70 deg.

As an example if you hooked up to a 3600 psi hose on a 100 deg. F day the dispenser could legitimately fill to 4100 psi! This is over the 3750!

All of this leads to a situation where you could be risking over pressurization depending on the temperature, the fill station/dispenser compensation etc.

I don't like the idea of switching nozzles for a coupla of reasons. The first I’ve covered above, the second is the legal exposure you incur. If there ever were an accident, your case in court would go out the window if it were discovered that you'd switched to 3600psi for a 3000 psi system.

Stay safe,

afvman/Bill

[Dugless]

Re: 3000psi vs. 3600psi

Interesting, thanks for your input. However, when I fill up on at 3000, the pump shows that I get a fill at 100%. When I fill at 3600, the highest the pump has ever displayed was 88%. Does this mean the pump knows when to stop?

[afvman]

Re: 3000psi vs. 3600psi

Dugless, et al,

Not sure what the percentages refer to. Sorry.

Here's a chart that may help clear up the Pressure-Temperature realtionship.

B/R,

afvman

[jetboatjohnny]

Re: 3000psi vs. 3600psi

I fill with the 3,000 pump all the time and on my car the 600psi difference is only around 30 miles, Also with the heat of summer and the pump is set around 3700psi, I get about 20 less miles per tank, my light comes on at about 150 miles instead of (wintertime) around 170 miles.

[CraziFuzzy]

Re: 3000psi vs. 3600psi

Interesting, thanks for your input. However, when I fill up on at 3000, the pump shows that I get a fill at 100%. When I fill at 3600, the highest the pump has ever displayed was 88%. Does this mean the pump knows when to stop?

That is one of the advantages of a 3000# car in a 3600# world. The station's pressure was probably low from use. Such that a 3600# vehicle could not get a full fill (station pressure was probably around 3200#) This would still top off a 3000# car, but could only get a 3600# vehicle to 88% (3168# @ 70F)

[Dugless]

Re: 3000psi vs. 3600psi

Not sure I follow you. Do you fill up your CV at 3600#?

[CraziFuzzy]

Re: 3000psi vs. 3600psi

Okay, to explain a little more, the stations that show a % completion, that number is a percent of the full tank pressure. On a 3000# dispenser, @ 70F, that would read 100% when your tanks got to 3000#. However, on a 3600# dispenser, it would read 100% at 3600#.

If the storage tanks at the station are low, at 3200#, that is the highest it would be able to fill ANY vehicle. If you fill up on the 3000# dispenser, it will bring your vehicle's takns to 3000# (100%) and stop. If you fill up on the 3600# dispenser, it would bring your vehicle's tanks up as high as it can (in this case, 3200#), which would be approx 89%.

And no, I have never filled my car from a 3600# dispenser, as that would be overpressurizing my tanks.

[freedml]

Re: 3000psi vs. 3600psi

Yes, the dispenser bases the percentage fill on the maximum pressure. so a 3000 fill is 100% on a 3000 dispenser and 83% on a 3600 dispenser. You have to watch it because some of them jump to "100%" no matter what to let you know that the dispenser is done.

[Dugless]

Re: 3000psi vs. 3600psi

This is what I got today. It stopped at 77% which came to 12.52 gge.

[CraziFuzzy]

Re: 3000psi vs. 3600psi

If it was 70F when you filled up, that would mean your tanks got filled to 2772psi (3600* 0.77). I'm sure it was hotter than that out, so you probably got a higher pressure. I'm not really sure what you are asking though. The reason you didn't get 100% has nothing to do with your car, it is just all the station had available (probably due to use). If this is routinely around what you are getting, that station just gets used that much. You probably should be using the 3000# pump anyways, and not risk damaging your tanks/car/self/others.