FMQ2-36 Temperature Question

[rgliedt]

Is it important for the vehicle to be in the same temperature environment as the fuelmaker when it is fueled? Let’s say for example that the fuelmaker is in a ventilated but heated structure which is maintained at 60 degrees, but the car is outside in a 30 degree air temp and you run the hose outside to fuel it.
My understanding is that the fuelmaker is automatically temperature compensating when it fuels. So I am wondering if there might be a concern that the fuelmaker might overpressure the tank?

[Amfuel]

Re: FMQ2-36 Temperature Question

Both the vehicle and the Phill should be in similar environments.

[John Mitton]

Bad idea

The scenario described would cause the vehicle to overfill and possibly pop the pressure relief devices on the vehicle cylinders. Review page 8 in the Installation manual, or page 3 in the Operating manual for the temperature vs. psi schedule.

Post #11 on this thread has the Boyles law curve:

http://www.cngchat.com/forum/showthread.php?t=3797

[cngaz]

Re: FMQ2-36 Temperature Question

First it doesn't sound very efficient to say ventilated and heated in the same statement. Second an FMQ 2-36 is not approved for indoor installation without additional equipment. Phill is the only model approved for indoor installation at a residence. If you have ever looked at an ice rink with a natural gas ice resurfacer, they have methane detectors, interlock devices to shut the FM down if there is a leak, and then the FM is still outside with a remote fueling panel located inside that transmits the temperature at the fueling point to the FM. Temperature compensation when fueling is important.

[Steve]

Re: FMQ2-36 Temperature Question

It looks like Phill (and FMQ) will try to fill the vehicle based on the ambient temperature on where the unit is located:

http://www.cngchat.com/forum/showthread.php?t=2977

If the FMQ is outside and the car is parked in the garage then the FMQ will pressurize the tanks according to the FMQ's temperature reading. In other words, you will not get a complete fill because my FMQ will fill to the lower pressure because of the lower ambient temperature reading of the FMQ and the higher ambient temperature of the car.

For the scenario where the Phill is inside (because we would never install an FMQ inside) and the car is outside, then the Phill would pressurize the tanks according to its ambient temperature which means at 30 F, your tanks would be at a pressure of 3600 for the Phill's temperature of 60 F.

So, I just wouldn't let my car warm up in the sun after such a fill. Also, you would get more natural gas in your tanks in this condition.

[freedml]

Re: FMQ2-36 Temperature Question

It is a problem equal to the size of the temperature difference. In So. Cal. it would not be a big problem because it never gets that cold. But if your car is outside freezing and the control unit is toasty warm inside, you theoretically could build up enough pressure to pop the relief valve later in the day when it warms up outside.