My initial fill on new system the supplier of N20 just filled it up. Took 5 min.

Now I filling a station closer to my home and they say they cant fill it as I wait as it bottle needs to be frozen before fill.

why is that necessary?

TY.

 

They can somehow get more into it when cold. If they dont have a pump and are filling from direct pressure differential from mother bottle, they will freeze it over night and fill it. My one local shop used to do this

 

If you freeze it before you fill it, it fills MUCH faster and sometimes with little to no use of their pump.

My guess for their requirement is either ease of filling(IE they don't have to use their pump) or they don't have a pump and are simply using a large cylinder and line to fill bottles(which I did for many years).

Having the mother bottle warm and the bottle that being filled frozen is easy!

 

OK I think I understand. There is a cost factor in the purchase of a high pressure pump. One station had it another not.

 

I fill this way from the mother bottle I keep in the garage. The bottle from the car goes in the freezer overnight and then fills almost instantly from the mother bottle without using a pump at all. Just elevate the mother bottle and let gravity and physics handle the rest.

If you use nitrous a lot you might want to look into filling your own bottles. You can buy automotive grade nitrous oxide from welding supply stores in 50lb bottles for less than half the per lb price a speed or automotive retail shop will charge. You just need a scale and a way to get the mother bottle in the proper position for filling.

 

The reason this works is the exact same reason why heating a bottle works just the opposite. Nitrous is a liquified gas, so what happens is when you heat it up it generates pressure. When you have a cold bottle connected to a warm one there's a pressure difference. Like anything else with a pressure difference that's joined up it will ultimately equalize out if given the chance. Since you have the source tank upside down it pushes liquid into the tank you're filling. Here's a chart for reference.

http://nitroussupply.com/bottletemp.php