I noticed this was listed under Military Equipment and Britain in WWII, as well as Firearms, so let's go with the BREN for this one.
Yes- belt fed, air cooled, gas operated machinegun. Gas operated means it uses some of the expanding gasses from a fired cartridge to operate the action.
Air cooled, magazine fed, shoulder fired, gas operated, lightweight.
Lewis gun
The Kalishnikov PKM is a gas operated, belt fed, air cooled, automatic only, machine gun.
The M240B is an American variant of the Belgian FN-MAG machine gun. It is a belt-fed, gas operated, air cooled machine gun which fires the 7.62x51 NATO cartridge.
A gas is a gas, as the name suggests. It can, along with liquid be referred to as a fluid. Cooled and pressurised sufficiently it can become a liquid and cooled further, a solid.
Another name for M4 is the "M4 Carbine." It is a lightweight, air-cooled, gas-operated, magazine-fed carbine that is widely used by the U.S. military and other armed forces around the world. The M4 is known for its versatility and adaptability, often featuring a collapsible stock and a Picatinny rail for mounting accessories.
Air and hydrogen gas can be pumped through
The correct term for an air hoister is just air hoist. An air hoist is a pneumatic hoist, which means it is operated by pressurized air or gas.
When a balloon is cooled, the air inside it contracts and takes up less space, causing the balloon to shrink. This is because the volume of a gas decreases as its temperature decreases, following the ideal gas law.
If air is compressed and cooled, the temperature of the air will become negative. Now depending on how much humidity there is in that air being compressed we might get some water droplets as it is being cooled. Carbon dioxide when compressed and cooled we get dry ice.
The M4 carbine is a shorter and lighter variant of the M16A2 assault rifle. The M4 is a 5.56×45mm NATO, air-cooled, direct impingement gas-operated, magazine-fed carbine. It has a 14.5 in barrel and is 33 inches long.. It weighs 6.5 lbs.