Take a pip bomb and get near anyone of those 3 items, gas tank, propane tank, or oxygen can. Aim on it and throw the pip bomb. After throwing it, quickly grab the item. You'll see that your person just act like if he picked up a weapon, but really the gas tank,propane tank, or oxygen can is hidden away and safe till you reach the safe room and start the chapter, it will fall out and be right under you.