| Advantages of the balanced pressure steam trap:
Small, light and has a large capacity for its size.
The valve is fully open on start-up, allowing air and other
non-condensable gases to be discharged freely and giving
maximum condensate removal when the load is greatest.
This type of trap is unlikely to freeze when working in
an exposed position (unless there is a rise in the condensate
pipe after the trap, which would allow water to run back
and flood the trap when the steam is off).
The modern balanced pressure trap automatically adjusts
itself to variations of steam pressure up to its maximum
operating pressure. It will also tolerate up to 70°C
of superheat.
Trap maintenance is simple. The capsule and valve seat
are easily removed, and replacements can be fitted in a
few minutes without removing the trap from the line.
Disadvantages of the balanced pressure steam trap:
The older style balanced pressure steam traps had bellows
which were susceptible to damage by waterhammer or corrosive
condensate. Welded stainless steel capsules introduced more
recently, are better able to tolerate such conditions.
In common with all other thermostatic traps, the balanced
pressure type does not open until the condensate temperature
has dropped below steam temperature (the exact temperature
difference being determined by the fluid used to fill the
element). This is clearly a disadvantage if the steam trap
is chosen for an application in which waterlogging of the
steam space can not be tolerated, for example; mains drainage,
heat exchangers, critical tracing.
|
