IMPACT SUBSEA
INNOVATIVE UNDERWATER PRODUCTS
www.impactsubsea.com
Document No:
0000.1913 |
Version No:
1.2 | 23
rd
April 2020
19
8.0 Theory of Operation
8.1 Flooded Member Detection - Basic Principles
This section examines how Flooded Member Detection is achieved by the system.
For the purpose of detecting Flooded Members, the ISA500 is a hydro-acoustic device, which
utilises sound pressure waves in order to determine the presence of water or liquid in a
member.
Acoustics (also known as hydro-acoustics or sound pressure waves) are used by the ISA500 due
to their high efficiency in travelling through water or liquid. Through water acoustics can travel
far greater distances than signals in the light or radio frequency spectrum. Thus, are the ideal
method to use for measuring distance underwater.
The ISA500 operates by emitting an acoustic pulse into the
member to be tested. This pulse
travels through the water, the wall of the member and into the inside.
If the member is full of water/liquid (flooded) the sound will continue through the member to
the corresponding side.
At which point part of the pulse is reflected back to the ISA500.
This reflected portion is detected by the ISA500 and the time taken for this acoustic pulse to
travel from the ISA500, bounce off the corresponding member wall and return is recorded.
The distance the acoustic pulse has travelled can then be calculated by the simple equation:
Distance = Speed x Time
In water, the speed of sound is typically around 1,500 meters per second. This is
influenced by
various factors (temperature, salinity & pressure). However, for the purpose of this
explanation, we will assume a speed of sound of 1,500m/s.
