FMQ-2-36 used on 3000 psi car?

[hsgreer]

I've recently purchased a 2000 Ford F150 that came with a FMQ-2-36 home refueling station. I also have a 1996 Crown Vic that has 4-3000 psi OEM factory tanks and a 1-3600 psi tank that was added later. Can I use the station on both cars without damaging the tanks on the Crown Vic?

[John Mitton]

Don't do it!

As you probably found out, the Crown Vic's P30 fill connector won't hook up with your FMQ-2-36's P36 nozzle as the fittings are intentionally not compatible. Overnight time-filling of 3000 psi cylinders to 3600 psi will weaken the structural integrity creating a dangerous situation over time.

My suggestion is you swap the FMQ-2-36 for an 3000 psi FM2 or better yet an older FM4 (lots of them up in Canada) and pocket the difference. I had an FM4 for a long time with my Civic and never really missed the extra 15% range or so of what my new FMQ-2-36 provides.

If you post the proposed swap in our Marketplace forum you will probably get a few takers

[Adrian]

Re: FMQ-2-36 used on 3000 psi car?

You can safely (and legally) fill a cylinder to 125% of its working pressure even on a fast fill. We all do it in the summer in CA where we get 3700-4000 psi fills on 3600 psi cars due to temperature compensation widely accepted throughout the industry. Fast fills cause more stress on your tank and other parts seeing the higher pressure than a slow fill. I doubt CE and Trillium (not Questar since you guys in UT never see high pressure fills from what it sounds like) would voluntarily take on a liability by filling to 120% of rated pressure in the summer months. Their action to me confirms that not only is this safe, it's not perceived as a liability.
In your case, 3,000X1.25=3,750. 3,600<3,750.
Your FMQ2-36 will not fill above 3600 psi and is a slow fill compressor. I think an argument could be made that slow filling a 3,000 psi system to 3,600 psi is actually safer than fast filling your 3,000 psi car in the summer to 3,750.
Then there is the liability argument. If something was to go wrong, there would likely be a presumption of negligence (not conclusive proof!) in your disfavor. This presumption might be overcome by simple logic (see above) showing you are not introducing more risk.
I'm not advising you to do anything; but do look at the numbers before making a decision. Blanket statements taking hard line positions are rarely justified. This is in my opinion a debatable topic.

[CanAm]

Re: FMQ-2-36 used on 3000 psi car?

Where are FM4 available in Canada?

[John Mitton]

Adrian has it backwards

You can safely fast-fill to 125% of rated tank pressure at the applicable ambient temperature. This is due to heat created during a fast-fill operation which, when the tank cools down a bit, drops the pressure. Some stations compensate for ambient temperatures as follows (kudos to Jennifer for this nifty chart):




Fuelmaker's time-fill products all compensate similarly.

Now here is where you come in. The FMQ-2-36 time-fill system during the summer might routinely fill your 3000 psi cylinders to 4125 psi. And, unlike a fast-fill operation where the pressure will soon drop a few hundred psi after driving away from the station, the pressure from your time-fill operation remains until you drive the vehicle far enough to reduce pressure down to the level the tank was rated for. Repeated time-filling of these cylinders in such a manner is dangerous.

[Adrian]

Re: Adrian has it backwards? Maybe not.

You can safely fast-fill to 125% of rated tank pressure at the applicable ambient temperature. This is due to heat created during a fast-fill operation which, when the tank cools down a bit, drops the pressure. Some stations compensate for ambient temperatures as follows (kudos to Jennifer for this nifty chart):




Fuelmaker's time-fill products all compensate similarly.

Now here is where you come in. The FMQ-2-36 time-fill system during the summer might routinely fill your 3000 psi cylinders to 4125 psi. And, unlike a fast-fill operation where the pressure will soon drop a few hundred psi after driving away from the station, the pressure from your time-fill operation remains until you drive the vehicle far enough to reduce pressure down to the level the tank was rated for. Repeated time-filling of these cylinders in such a manner is dangerous.

Your assumption that Fuelmaker home products compensate for temperature exactly like commercial filling stations is incorrect based on the information put out by Fuelmaker. Yes , they (FMQ compressors) deliver less pressure below 59F, but not more pressure above 59F. Actually, looking at the FMQ2-36 manual, it will never deliver more than 3700 psi . In fact, it delivers 3600 psi +/- 100 psi at all temperatures above 59F. Please see page 8 of the attached FMQ2-36 service manual. Since the maximum 3700 psi will be at the same ambient temperature as the car (outside), it will not heat up any more during the day and the pressure will not rise above that. Again, please look at the specifics before drawing conclusions.

John, let me know what you think after looking at the Fuelmaker manual.

[John Mitton]

Re: FMQ-2-36 used on 3000 psi car?

Good catch, Adrian.

If it were my vehicle I still would not want to repeatedly time-fill the 3000 psi cylinders to 3600 psi. I have asked Highmarker (Jared) to chime in on this, as he is a cylinder engineer. Hopefully we will hear from him soon. One thing we won't discuss is circumventing the safety mechanism Ford put on the vehicle to ensure it only fills to 3000 psi.

[larrycng]

Re: Adrian has it backwards? Maybe not.

Your assumption that Fuelmaker home products compensate for temperature exactly like commercial filling stations is incorrect based on the information put out by Fuelmaker. Yes , they (FMQ compressors) deliver less pressure below 59F, but not more pressure above 59F. Actually, looking at the FMQ2-36 manual, it will never deliver more than 3700 psi . In fact, it delivers 3600 psi +/- 100 psi at all temperatures above 59F. Please see page 8 of the attached FMQ2-36 service manual. Since the maximum 3700 psi will be at the same ambient temperature as the car (outside), it will not heat up any more during the day and the pressure will not rise above that. Again, please look at the specifics before drawing conclusions.

John, let me know what you think after looking at the Fuelmaker manual.

As a cylinder inspector, I hope I would not encounter a situation as described above. Even if the FMQ2-36 does not go above 3700 psi. The minute the temperature of the cylinder goes up 10 deg. F, the cylinder's pressure go up 100 psi (according to the chart in this tread and basic physics). That would put the pressure in cylinder over 125% of service pressure on the 3000 psi cylinders. The cylinder should be inspected immediately (CGA C-6.4 sect.7.2) and NFPA 52 6.12.4)

This would be considered level 2 damage (being generious) and the cylinder manufacturer should be notified concerning further inspection and disposition. If that information can not be located because the manufacturer is out of business, the cylinder damage level should be moved to level 3 and the cylinder destroyed (CGA C-6.4). 6.4 also indicates you should get a second opinion.

Bottom line, don't push the safety limits for a couple extra miles of range. Don't devise a means to fill 3000 psi cylinders to "3700" psi, even slow fill. Granted most factory Ford cylinders are steel type 1 or 2 and prety stout.

So soon you forget Super Shuttle and Corona (granted they were not steel cylinders) but we don't need any more problems.

Don't push it CNG doesn't need it

Larrycng

[cngmike]

Re: FMQ-2-36 used on 3000 psi car?

DOT only allows for filling to 125% when fast filling.

[Adrian]

Re: Adrian has it backwards? Maybe not.

As a cylinder inspector, I hope I would not encounter a situation as described above. Even if the FMQ2-36 does not go above 3700 psi. The minute the temperature of the cylinder goes up 10 deg. F, the cylinder's pressure go up 100 psi (according to the chart in this tread and basic physics). That would put the pressure in cylinder over 125% of service pressure on the 3000 psi cylinders. The cylinder should be inspected immediately (CGA C-6.4 sect.7.2) and NFPA 52 6.12.4)

This would be considered level 2 damage (being generious) and the cylinder manufacturer should be notified concerning further inspection and disposition. If that information can not be located because the manufacturer is out of business, the cylinder damage level should be moved to level 3 and the cylinder destroyed (CGA C-6.4). 6.4 also indicates you should get a second opinion.

Bottom line, don't push the safety limits for a couple extra miles of range. Don't devise a means to fill 3000 psi cylinders to "3700" psi, even slow fill. Granted most factory Ford cylinders are steel type 1 or 2 and prety stout.

So soon you forget Super Shuttle and Corona (granted they were not steel cylinders) but we don't need any more problems.

Don't push it CNG doesn't need it

Larrycng

Just curious...since there is no difference between using an FMQ2-36 to fill to 3600 psi and fast filling to 3600 psi (other than the fact that fast filling causes more stress) do you also not advocate fast filling during the summer when most CNG stations crank the pressure up to 3600-3700 psi for 3000 psi systems?
As far as the temperature going up 10F...I see your point. If a 3000 psi car was slow filled overnight and it reached 3600 psi at 2 AM when the temperature was 60F or less and the car remained parked without being driven until say noon when the temperature could easily be 70F, the situation you are describing could happen when the tank temperature equalizes to the ambient temperature. Given it's mass and insulated surface area (the wrapping acts as insulation) this might take a while. To get a definitive answer, one would have to perform a heat balance calculation knowing the specifics of the tank material and thicknesses and surface area as well as the maximum ambient temperature to see how long it would take for a CNG tank to increase in temperature by 10F. It would be an interesting calculation, but it's been a while for me since I've done that.
I'm curious to see what Highmarker (Jared) thinks as well.

[Adrian]

Re: FMQ-2-36 used on 3000 psi car?

DOT only allows for filling to 125% when fast filling.

In that case the answer becomes simple: One cannot slow fill to 125% and my line of logic up to this point is moot.

[CraziFuzzy]

Re: FMQ-2-36 used on 3000 psi car?

There is the option of a seperate fill hose (P30) with a pressure reducer inline for the 3000# vehicle. Of course, most the reducers I've seen that would be appropriate are around $500+. I'm pretty sure this is basically how the 3000# fill hoses work at 3600# stations anyways.

[larrycng]

Re: FMQ-2-36 used on 3000 psi car?

Good points. My basic point is still not to exceed the stated service pressure of the cylinder and not push the pressures. Pressure be pressure no matter what the temperature.

I would be interested in the calculations. Also the difference in time between a sedan and a pick-up with shield. I've watched the pressures in a demo truck I had, without shield, go up with the ambient temperature (this was in the desert -- a type 2 aluminun). The pressure at 7am and about 70 deg. was right at 3000. At 11:30 with temp at 98 deg. the gauge at the tank was just over 3400.

I also know one individual who says in puts a wet towel over the tank in his GX while fueling to help keep the pressure down and get extra fuel volume. He also has different situation and equipment at his disposal. Don't agree with that one either

later

larrycng

[Highmarker]

Re: FMQ-2-36 used on 3000 psi car?

Here is my "chime" on this subject. Let me start out by saying that NGV2 is not specific on this matter. Here is what NGV2 says about overpressurization:

"Containers are designed to be filled to a pressure not exceeding any of the following conditions:
a. A pressure that would settle to 1.0 times service pressure at a settled temperature of 70°F;
b. A settled pressure of 1.25 times service pressure at 135°F; or
c. 1.25 times the service pressure immediately after filling, regardless of temperature.
Note: The fill pressure shall be temperature compensated to prevent pressures from exceeding the maximum pressures that are defined."

It also states:

"Any container which is believed to have been subjected to a pressure greater than 1.25 times service pressure shall be depressurized and removed from service."

Now, I believe that the main question here is: Would consistent pressurization of a cylinder to 1.25 times service pressure be dangerous for the cylinder? According to NGV2, one could draw the conclusion to be no.

As a desgin engineer of pressure vessels, I would also err on the side of safety. I would not recommend pressurizing any cylinder above is designated service pressure regardless of temperature.

[Adrian]

Re: FMQ-2-36 used on 3000 psi car?

Here is my "chime" on this subject. Let me start out by saying that NGV2 is not specific on this matter. Here is what NGV2 says about overpressurization:

"Containers are designed to be filled to a pressure not exceeding any of the following conditions:
a. A pressure that would settle to 1.0 times service pressure at a settled temperature of 70°F;
b. A settled pressure of 1.25 times service pressure at 135°F; or
c. 1.25 times the service pressure immediately after filling, regardless of temperature.
Note: The fill pressure shall be temperature compensated to prevent pressures from exceeding the maximum pressures that are defined."

It also states:

"Any container which is believed to have been subjected to a pressure greater than 1.25 times service pressure shall be depressurized and removed from service."

Now, I believe that the main question here is: Would consistent pressurization of a cylinder to 1.25 times service pressure be dangerous for the cylinder? According to NGV2, one could draw the conclusion to be no.

As a desgin engineer of pressure vessels, I would also err on the side of safety. I would not recommend pressurizing any cylinder above is designated service pressure regardless of temperature.

Looks like (b) would control most situations where one slow fills a 3000 psi system to 3600 psi overnight. Morning temperatures are likely in the 50-60F range and extrapolated to 135F, the pressure would surely be above 3750, 1.25X the service pressure of 3000 psi.