INSTALLATION, OPERATION and MAINTENANCE MANUAL | 23
Plate Material
Heat transfer plates are pressed from 304/304L or 316/316L stainless steel, 254 SMO,
or Titanium material. Other exotic alloys may be required to provide suitable corrosion
resistance to the liquids being handled (please contact your SPX FLOW representative
for availability of other exotic materials).
DuoSafety – Double Wall Plates
The APV DuoSafety GPHE plate is a double wall plate manufactured from two separate
sheets pressed together to form a single DuoSafety plate (Figure 11). Each APV
DuoSafety plate is equipped with a non-glue gasket, which seals and holds the halves
together.
The space between the two halves of the APV DuoSafety plate serves as a safety zone
in case of through-plate leaks. Should a leak occur in this safety zone (i.e., because of
corrosion wear or age of seals), this space provides an extra security against mixing of
the two liquids. The liquid will be discharged from the space between the two walls into
the atmosphere and avoid cross-contamination.
When leakage from an APV GPHE containing APV DuoSafety plates is observed,
immediate action must be taken to detect and replace the defective items before the
leak can proceed through both plate walls and cause cross-contamination.
If an APV DuoSafety GPHE is fitted with a safety screen, it will be necessary to
regularly remove the screen to observe that the plate pack edges have no tell-tale sign
of leakage. A visual check should be made at least every 3 months.
Leakage from an APV DuoSafety plate is always the early warning for the user
to act.
Note: APV DuoSafety plates use special gaskets which can be confused with gaskets
intended for single plates. Please confirm with SPX FLOW that you have the correct
gaskets.
Welded Plate Pairs
An APV welded plate pair is a right- and left-hand vertical flow plate laser welded
together to form a pair. This welded plate pair system is particularly suitable for use with
refrigerants such as ammonia and freon or with other aggressive liquids that would
otherwise attack the gaskets in a conventional heat exchanger plate.
When the welded pairs are installed in a frame, each pair is sealed to the next pair by
elastomeric seals (Figure 12).
Note: An APV welded plate pair cannot be separated for inspection and cleaning. It is,
therefore, important to prevent fouling and clogging of the welded passage. If fouling in
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