Apparatus are disclosed to bias a tube towards a seal. An example apparatus includes a pneumatic actuator having a diaphragm plate, a yoke housing, and a tube. The tube conveys pressurized fluid between the yoke housing and the diaphragm plate, wherein a first end of the tube extends through a first seal gland in the diaphragm plate to form a seal against an outer surface of the tube and a second end of the tube extends through a second seal gland in the yoke housing to form a seal against the outer surface of the tube. The first end of the tube has a first cross-sectional area that is greater than a second cross-sectional area of the second end of the tube to bias the tube toward the yoke housing during operation of the pneumatic actuator.