Perhaps what follows may be obvious for experienced professionals but this may not be true for the engineering student. Hopefully, this will be useful.
- Pressure and flow rate are related. This is, theoretically, stated by the energy and Bernoulli equation. Besides, this is also tru in practice. Increment and decrement of flow rate are related to changes in pressure.
- Flow rate increases with diameter; but also with pressure. If you wish to increase the flow rate two options are available: a) you may choose a larger pipe diameter or b) you may increase pressure. If you choose to increase pressure you must know that this cannot be changed arbitrarily and without control.
- The minimum flow rate is key. The reason is simple. When a pipe system is designed, it is so to operate under steady conditions at the lowest possible cost (without sacrifyce of safety, service life, etc.). Otherwise, you will be wasting money.
- Different pipe sizes may tranport the same flow rate. This is that, commercial steel pipes with ND 1", 1.5" and 2" may transport the same volume of fluid per minute for certain conditions. In other words, you could, theoretically, estimate the internal pipe diameter but in practice different real pipes may be available to transport the very same flow rate at a lower cost.
- Pipes may fail. This is that, in contrast with the classroom situations, the engineer should pay attention to the maximum pressure that the pipe may work at (before increasing the flow rate). Even steel pipes may burst or crack at overpressure conditions creating a real chaos.
- Be aware of phase changes. Phase changes may induce vacuum in the pipe exerting enormous local mechanical stresses in the pipe and creating risk for the structure. This is not apparent; but accessories like safety valves could be very useful in some cases.
Any question? Write in the comments and I shall try to help.
=========
Ildebrando
No comments:
Post a Comment