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Sudden Drop in Permeate quality
If a system is started and stopped frequently
and no provision is made to raise the
pressure slowly, movement of the membrane
column may damage O-ring seals and reduce
permeate quality.
If the quality of the permeate suddenly drops,
and poor membrane performance is not
suspected, remove the heads per instructions
in the Users Guide (See "OPENING THE
VESSEL" section on page nos. 10-12).
Inspect these O-ring seals carefully for
breakage or other damage. If the seals have
rolled out of the groove, or are damaged, this
may indicate excessive movement during
start-up and shutdown. To overcome this
problem, the vessel should be shimmed to
minimize
this
movement.
procedure for shimming as given below:
SHIMMING
Shimming is accomplished by placing spacers
between the adapter and the hub on the
permeate port on the upstream end of the
vessel. When done properly, shimming will
prevent
excessive
membrane elements and the adapters, thus
preventing potential damage of the O-ring
seals. The spacers used for shimming are
shaped like a plastic washer and are 0.20
inches thick.
The suggested procedure for shimming is as
follows:
1. With the membrane properly loaded, install
the adapter in the last element and place
the thrust cone on the head for the
downstream end of the vessel. (See
Replacing Element section on page nos.
13).
2. Install the head in the downstream end of
the vessel following Steps 1 through 4 of
the section entitled Closing Vessel on
page nos. 15-17.
TROUBLE SHOOTING
Follow
the
movement
of
the
3. Remove the product water tube seals from
the upstream adapter and the head seal.
4. Push the straight end of the adapter into
the permeate hub, just far enough so that
it is held by the adapter seal.
5. Line the adapter up with the product water
tube on the first element and install the
head fare enough into the vessel so that
you can place a locking ring segment in
the groove.
6. Carefully remove the head and observe the
space between the hub of the adapter and
the face of the permeate port. Determine
the number of spacers necessary to fill
this space.
7. Remove the adapter and place the product
water tube seals. Insert the adapter in the
product water tube of the first element.
8. Slide the number of spacers determined in
Step 6, over the end of the adapter.
9. Now close the vessel according to the
"Closing the Vessel" section which begins
on page no. 15
Vessel Shimming
Page 29 of 38
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