Portable Life Support System
|PLSS Type A|
|PLSS Type B|
|PLSS Type C|
All Portable Life Support Systems (PLSS) backpacks are equipped with a frame holding two oxygen tanks, a gas regulator to control gas flow, and a 500 km range space-band radio, in addition to the other equipment. They supply basic life support systems to the users of vacc suits and hostile environment suits.
The PLSS Type A is for short duration use. It is nothing more than two oxygen tanks connected through a regulator into the suit. Exhaust gas is vented directly into the exterior, no attempt is made to recycle it. This pack measures 70cm tall by 45 cm wide by 30 cm thick. The PLSS Type B is for general use of up to 20 hours duration. This pack measures 75 cm tall by 45 cm wide by 30 cm thick. The PLSS Type C is a general use system of up to 40 hours duration. This pack measures 85 cm tall by 45 cm wide by 30 cm thick.
All but the Type A system are equipped with a gas recycler that is capable of stretching the useful duration of oxygen tanks to as much as 8 hours per tank, depending on the user's exertions and the pressurization level of the suit. Each system is equipped with a chest control box that contains the pack's status displays (or telltales) and controls. Packs used with soft suits have straps to hold the pack onto the suit and a one meter umbilical that plugs into the suit. Packs used with hard torso or hard suits plug directly into the back of the suit; there are no straps or umbilicals used. All of the standard vacc suits and hostile environment suits work with any of the PLSS types.
Each pack is equipped with a special mount to enable the wearer to replace his own oxygen tanks without removing the backpack, and provision is made for extra tanks to be strapped onto the pack. Changing a tank takes 2 minutes per tank. Waste is collected into disposable plastic sacs. 
An optional urine reprocessor unit can be installed to extract water from body wastes. The wearer may drink the recovered water by means of a nipple installed inside the helmet. This recycler costs Cr50, masses 1 kg, and is available at TL–7.