The nitrogen was injected as opposed to the cars been pressurized. The crude was shipped at 140 degrees plus and relied on the expansion of the nitrogen through the cars to remove the oil. How much nitrogen? Wish I could answer that question, but it was over 30 years ago. I can tell you that the nitrogen was vented to atmosphere as the train was loaded in Bakersfield.
The phone companies still pump nitrogen into their older copper lines to keep them dry …
Quite a few years ago, there was a tire retailer (Acorn Tire, I believe) in the Chicago area that advertised that the new tires you bought from them were filled with nitrogen. It sounded like a gimmick to me.
It may be largely a marketing thing, but there are good reasons to exclude oxygen under pressure from the inside of a tire and to eliminate the water that is almost always carried over from garage air compressor setups.
A tire retailer in my area advertises that. In addition, certain upscale autos are delivered new with nitrogen filled tires. They will have a green tipped valve stem cap if so equipped.
Professional level racing normally use Nitrogen to inflate their tires. The use of Nitrogen allows for more precise measurement of the use parameters of the tires and their response to heat during use. Air contains water vapor - vapor that can become STEAM when heated beyond 212 degrees and add additional pressure to the desired inflation pressure. In racing, tires and their inflation pressure, form a portion of the total ‘spring rate’ of the entire suspension system which also includes the springs, shock dampers as well as resistance in all the movable suspension links. While it is realatively difficult to adjust the ‘hardware’ of the suspension, it is easy to adjust tire pressure when it is necessary to ‘tune’ the suspension to the surface upon which the race is being contested.
The nitrogen thing apparently comes and goes. Back in the late 1960’s (more or less), I remember a big advertising push offering nitrogen for tires. I figure they couldn’t compete with free air.
On Balt’s point, I’ve always thought it important to keep out moisture, especially when watching them wet the tire bead to make mounting easier.
And, air is not always free anymore. I noticed, in the last week or two, air dispensers which require a few coins before your can fill your tires. SInce I do not drive anymore, this does not affect me particularly.
I doubt that many people have cooled off by blowing air in their faces as I saw Jeff (of “Mutt and Jeff”) doing 65-75 years ago.
To do Nitrogen ‘properly’ the tire, once mounted in ‘atmosphere’ conditions need to have a vacuum pump attached to evacuate the ‘air’ that is in the mounted tire. Once the ‘air’ has been evacuated the nitrogen can then be added.
I suspect what retail tire outlets are doing is just adding nitrogen to tires that have been mounted with ‘atmosphere’ conditions and the water vapor from the atmosphere is still in the tire. From my view point Nitrogen in consumer tire applications is just a gimmick to get people to spend, spend, spend. Junk Science sells.
The solution used to mount/dismount beads over the wheel rim is a commercial product at tire shops, however, for home tire mount/dismounts a solution of water and dishwashing liquid performs the trick.
In as much as most retail gasolene outlets no longer have mechanical shops as a part of the overall operation, they have no need for a air system to support the mechanics air tools, which was the supply in the days of ‘free air’. Nowadays the air supply is a ‘on demand’ pump that is activated by the money that is required to turn the pump on.
Just do what I do: go to one of the tire chain stores, or a ‘garage’ like Firestone or Midas car care, where they will have a handy air hose reel at the front of one of the bays. I have never yet been refused the use of this hose and chuck to put air in even large, relatively flat tires free. And the setup is much preferable to the old service-station air facilities, many of which were decidedly run down with dubious compressed-air quality.
Since I use air tools at home - I have my own air compressor, I wish it was bigger, but I can make it do what I need it to do.
I just carry a little pump that plugs into the cigarette lighter.
Conversations are fascinating. We started out talking about tank trains.