Dear Liu,
The matter is very simple. As the test medium is
charged into the test loop, the level of water rises
gradually replacing the air already / otherwise
present in the system. Unless there is an exit of this
air (the last segment) water will not be filled fully,
since any sector of trapped air will act as a
compressible gas piston and any amout of hydraulic
pressurising attempted will render the effort futile
as this bubble gets smaller and smaller by reducing
its volume. Hydraulic pressure will build up only if
it is full of liquid medium.
In order to achieve this, high point vents at all
trapped segments are required. While draining the
water after the hydro-test, this valve has to be kept
open. This is equally important or else the vacuum
formed inside, if the travels are too steep and
vertical (water barometer effect) on account of the
withdrawal of water, can cause collapse of the wall
and sometimes the connected equipments as well, if any
are taken in the loop.
Likewise drain at all low points are required in order
to drain the "last drop" of test medium left behind.
I hope the points have been adequately cleared. If
not, please mail back.
Cheers!!!
--- "Liu, Robert" <robert.liu@ue-1.com> wrote:
> Dear members;
>
> Is it true that vent and drain are needed at every
> high and low point of
> piping if water is used for hydrotest? what if air
> or steam are used?
>
> Can someone explain the general procure about how to
> use them in the
> hydrotest?
>
> I know these question seems too junior but I do have
> confusion on it. your
> response is appreciated.
>
> Thanks
> Robert Liu
>
>
>
>
This archive was generated by hypermail 2.1.8 : Mon Oct 27 2008 - 20:23:58 EDT