A tube clamp includes (i) a tube holding portion; (ii) a first arm extending from a first end of the tube holding portion; (iii) a second arm extending from a second end of the tube holding portion, the second armed curved so that a first catch located at a distal end of the second arm can be snap-fitted to the first arm to occlude a first tube extending through the tube holding portion; and (iv) wherein the first arm includes a locking feature configured such that when a second tube clamp is mated with the tube clamp, the locking feature interacts with a second catch of the second tube clamp so that the second tube clamp is prevented from occluding a second tube.