One way air-valve for camping mattress?
My mother's air bed (camping mattress) has a patched hole in it but it still leaks air. I want to hook up a tube from the mattress to the pump so when she needs more air, she just needs to turn the pump on. However, when she lies on the mattress, the air will reverse out the tube and into the fan-operated pump (the pump circulates air using a fan and has a deflating function). I want to make a one-way air valve so it can't do that. Thing is, I do not know how to make one. Any suggestions?