I am looking to buy a centrifugal monoblock pump for my laboratory. The suction and discharge sizes are mentioned as 12mm x 12mm. Does anybody know what does it mean? Does it mean 12mm OD, or does it mean 1/2" BSP?
Centrifugal pumps typically go by nominal pipe size for the inlet and outlet connections. The first number is typically the inlet, and the second is the outlet. Normally the outlet is smaller (which is why you'll see 10"x8" centrifugal pumps but never 8"x10"). This is partly due to mechanical efficiency and partly to get a justifiably higher pressure. However in small sizes such as this one, both connections are the same.