Horizon Fitness H-1000 User Manual page 24

The outlet of the purge valve should be far away from
the stack. Don't let the hydrogen from purge valve back
to the stack, otherwise it would damage the stack.
Note: The tube between stack output and purging valve is
required to be less than 20cm. The tube connected to the purging
valve output is required to be less than 30cm. The inner diameter
of the tube is required to be more than 2mm.
H-1000 Fuel Cell Stack User Manual V4.4
21