GE EVT-Pro 2.0, Operation And Technical Manual, Page: 28 / 60

SECTION 21 (Continued)
Lift line
– From the start of the test, the lift line slowly increases. This increase is a result of
flexing (only millimeters) in the EVT PRO 2.0
®
bracket and the extension of the PRV
spindle and hardware connections. A significant increase in lift occurs at the moment the
PRV opens.
Acoustic Line
– The acoustic line responds to vibrations travelling through the PRV caused
by flow that occurs when the PRV opens. A spike will occur in the acoustic line indicating
that the PRV has opened.
For
PRV’s in compressed media service, both the hydraulic force and lift line can be used
to identify set point. In some cases, only one line may provide a clear indication of set
point. The acoustic line may also be used to assist in identifying set point, however, the
acoustic signal responds to the first indication of lift (leak point) and should not be used as
the only indication of set point.
For
PRV’s in liquid service, the acoustic line is the primary indicator for set pressure. Both
the hydraulic force line and the lift line can be used to assist in identify set point in liquid
service, however, since liquid does not expand, they cannot be used as the sole indicators
for determining set point.
SECTION 22
EVT PRO 2.0 ® FUNCTIONAL (EFFECTIVE) SEAT AREA
Accuracy of the functional seat area is critical to the overall accuracy of in situ testing. The
EVT PRO 2.0
®
software contains various methods for determining functional seat area.
There are four (4) databases available for selecting the functional seat area along with
three (3) additional methods for calculating the functional seat area.
The databases are:
User Defined Seat Dimensions
– this database is populated via data input by the
technician.
EVT PRO 2.0
®
Database Seat Dimensions
– this database contains functional seat areas
provided by Consolidated®.
Competitor’s Database Seat Dimensions – this database contains functional seat areas for
competitor valves. This data has not been lab tested and is based on field information only.
Standard Orifice Size
– this database contains functional seat areas based on the standard
orifice size of the PRV. This method should only be used when the difference between
operating pressure and set pressure is minimal and a relatively large orifice PRV is being
tested. The software will determine if the test criteria meets allowable standards and a
green light (refer to figure 22.1) on the data screen will indicate testing can continue.
Figure 22.1
– Example of Allowable Standards Light
EVT PRO 2.0
®
- EXPLANATION OF GRAPH
EVT PRO 2.0
®
Operations and Technical Manual (Rev 1.0
– 2016)
NOT FOR COPY OR DISTRIBUTION Page 24